Editor's Note: If your name is Ben and you recently posted a comment about this Red fox article via the webring forum, could you please drop me an e-mail?   I have a couple of things I'd like to discuss further and the reply option on the webring site doesn't seem to do much!   Many thanks.

SECTIONS:

-- Taxonomy
-- Length
-- Weight
-- Colour / Appearance
-- Senses
-- Distribution
-- Longevity
-- Sexing
-- Activity
-- Dens
-- Territory & Scent Marking
-- Abundance
-- Predators
-- Food & Feeding
-- Breeding Biology
-- Behaviour & Social Structure
-- Interaction with Humans

Taxonomy: The great London-born physiologist Thomas Huxley made his detailed study on the classification of the dogs (Canidae) in 1880, all 50 pages of which were published in the Proceedings of the Zoological Society of London.   Huxley -- often referred to as Darwin's Bulldog because of his passionate, evangelical adherence to Darwin's theories of evolution -- divided the canids into two groups based on various cranial and dental characteristics: the Alopecoids (true foxes) and the Thooids (hunting dogs, wolves, and South American foxes).   The state of canid classification has changed somewhat since Huxley's day and there are currently six fox genera -- Urocyon (the Gray Foxes), Otocyon (the Bat-eared Fox), Pseudalopex (the Pampas and Sechura foxes), Lycalopex (Hoary foxes), Cerdocyon (Crab-eating foxes) and Vulpes (the "true" foxes) -- comprising 23 species, 12 of which are contained within the Vulpes genus.

From the molecular data we have for the Vulpes genus, we have been able to untangle the evolutionary history of these canids.   It appears that the vulpine foxes date back to the mid-Miocene (ca. 10 million years ago) and that the Red Fox began to diverge from the Cape Fox (Vulpes chama) some 5 million years ago, although there is currently no fossil evidence to support this suggestion.   Also, while fossil evidence suggests that the Arctic (Alopex lagopus) and Swift (Vulpes velox) foxes aren't closely related, recent chromosomal data show that they share a karyotype unique to these two species, suggesting a close common ancestry; the two species also show a clear similarity to the Red fox.   The North American Red fox is considered by some authors to be a distinct species (Vulpes fulva), although most now accept that it is a conspecific of (i.e. belongs to the same species as) Vulpes vulpes, or relegate it to subspecies rank (Vulpes vulpes fulva).   The current taxonomy of the Red fox (Vulpes vulpes) is still somewhat equivocal and there have been 48 subspecies of Vulpes vulpes proposed.   The problem arises because these subspecies are -- in most instances -- poorly defined and, as such, different researchers have different ideas of how many subspecies are valid.   In their Atlas of European Mammals, Anthony Mitchell-Jones and his co-workers consider a maximum of five -- more likely four -- of the European subspecies to have any true validity.

Red foxes in Britain and parts of Europe (e.g. Germany) were formally classified as the subspecies Vulpes vulpes crucigera, originally described by German naturalist Johann Matthäus Bechstein in 1789.   The word crucigera is Latin for "cross-bearer"; presumably, Bechstein's description was based upon a 'cross' fox (see: Colour).   Regardless, Bechstein considered that, based on smaller size and differences in dentition and skull morphology, British foxes represented a distinct subspecies.   However, Red foxes are very variable both within Britain and throughout their range.   Indeed, given the continuity of range of the Red fox it remains to be seen whether any truly definable subspecies can actually be recognized.   Ergo, most authors consider that V. v. crucigera is a synonymy of the type specimen (i.e. simply a slight variation of Vulpes vulpes vulpes).   Ultimately, in order to establish any valid subspecies (if there are any) we need more molecular data on Red foxes from across their geographic range.   In the meantime, the current classification of the 'British' Red fox is as follows:

Length: The Red fox is the largest fox in the Vulpes genus.   Globally, 45 – 90cm (1.5ft – 3ft) head & body length; foxes can reach 1.5m (5ft) TL (including tail).   In the UK, adult male foxes typically range between 67cm and 72cm (26 - 28in.), while females fall between 62cm to 68cm.   The tail, or brush, makes up roughly one-third of the total body length; the longest record for a brush I have come across is 55.5cm (almost 2ft!). (Back to Menu)

Weight: In Britain, the average weight of an adult male fox is around 6.5kg (14 lbs), with a range of 4kg to 8 kg (9 - 17.6 lbs); adult females average 5.5kg (12 lbs), with a range of 4kg to 6kg.   Globally, the range of weights for Red foxes is 3 – 14kg (31 lbs).   Red fox mass follows Bergmann's Rule -- that body size is correlated with latitude -- so foxes in the north of their range tend to be larger than those occupying more southerly areas, although the effect may be diluted where introductions have been made.

Colour/Appearance: Red foxes are (as per above) medium-sized canids with a slender, whiskered muzzle and large pointed, erect ears.   Colour is highly variable; ranging from yellowy-red to black.   There are four main colour phases (Red, White, Silver and Cross), which are genetically inherited.   'Silver' (or Black - see Right) specimens are generally found at high latitudes and account for about 10% of colour variants, while white colour morphs (some of which are albino) are reported further south.   'Cross' foxes are red, with a black line of hair down the middle of their back and across the shoulders; they account for some 25% of colour morphs.   'Red' morphs are the most common and display a reddish-orange coat with a white chin, white fringed upper lip, white underside, black ears, black feet and legs, black nose and amber eyes (cubs eyes are blue).   A white tip to the tail is present in many individuals, but by no means all.   In very rare cases, 'Samson foxes' are reported - these individuals have lost their guard hairs and have tightly curled underfur, giving them a 'woolly' appearance.

Foxes undergo a protracted (extended) moult for much of the summer, ready for the growth of their winter coat, which is present from October to February.   Some foxes may begin to moult in late February, but most don't start until April.   This moult leads to a "piebald" appearance during much of the Spring and early Summer because new hairs grow first on the lower legs, spreading to the flanks by early July and the back and tail by late August; the re-growth is usually complete by late October or early November.   Often, breeding vixens begin to moult before barren vixens or males and can look very 'tatty'.   From late January or early February the hairs become brittle and the tips begin to break, so the coat begins to lose its condition. (Back to Menu)

Senses: Foxes are superb hunter with a finely-tuned battery of senses that allow them to interpret the outside world and respond accordingly to catch their prey.   Foxes, unlike most canids, have vertically-slit pupils; these can be closed more tightly than rounded pupils and allows their owner to hunt across a wide variety of different light conditions.   In his 1907 paper "Experiments On The Function Of Slit-Form Pupils" William Abbot suggested that a vertically-slit pupil may also help a predator to focus sharply on small, ground-based prey.   The retina of foxes is dominated by rod (low-light) cells, although there are some cone cells present, which might allow for limited colour vision.   Overall, the domination by the rods -- information from which is pooled prior to being sent to the brain, unlike cone cells that have a faster response and are arranged in smaller groups per nerve -- suggests that the image foxes see is probably rather poor; they can invariably detect movement better than humans can (and function in lower light conditions), but this essential increase in motion sensitivity is at the expense of the far less important features of colour and detail.   Indeed, in Town Fox, Country Fox, John Vesey-Fitzgerald notes that fox eyes lack a macula -- the highly sensitive central part of the retina, containing the fovea, responsible for our perception of detail (without it, reading this website would be impossible) -- although I've been unable to find the anatomy studies to corroborate this.   Nonetheless, observations in the field suggest that foxes are myopic (short-sighted); it can run through vegetation without incident, but will approach stationary objects to within a few metres unless another sense alerts it to danger or the object moves.   During his studies on foxes, Finnish biologist H. Osterholm concluded that vision is a key factor in finding food during daylight but, as one might predict, plays 'second fiddle' to hearing at dusk and in the dark.

Fox hearing is shifted towards low frequencies; those most readily indicative of rustling prey.   In their diagnosis of the Red fox as part of the Canid Specialist Group's Canids: Foxes, Wolves, Jackals and Dogs, David Macdonald and John Reynolds write:

"Red foxes can locate sounds to within one degree at 700 - 3,000Hz, though less accurately at higher frequencies."

The above statement is based on work on captive foxes in Finland; the same study found that at frequencies of 18kHz, the foxes were only able to locate the source within five degrees and that it could only be located accurately 90% of the time.   A similar study published 11 years after the Finnish trials used slightly different sounds (pure tones) and yielded slightly different results.   At frequencies between 900Hz and 14,000kHz, foxes were able to home in on the source in more than 90% of trials; 3.5kHz was the peak frequency, at which foxes performed best.   However, even at frequencies as high as 34kHz, the foxes were able to find the source more than 70% of the time.   Humans, by comparison, can -- depending on age -- hear in the region of 15Hz to 20 kHz.   For foxes, sound is important not only for hunting, but also for detecting danger -- in his Town Fox, Country Fox John Vesey-Fitzgerald tells how a vixen he was watching heard a man approach on soft earth some 30 seconds before he came around the blind bend 83m (272 ft) from the den  -- and keeping in touch with other foxes.

There are few studies presenting empirical data on fox sense of smell, although behavioural experiments and field observations suggest that foxes have a keen sense of smell.   Many authors have written about how foxes have seemingly been able to tell strangers from regular foxwatchers on the basis of scent alone and observations on fox social interaction and the use of scent marking (both application of scent to each other and to conspicuous objects within a territory) suggest that scent plays a pivotal role in fox society.   During his studies on captive foxes, Dr Osterholm concluded that his subjects couldn't find the pieces of meat that he'd buried in a 10cm (4 in.) deep hole from more than half a metre (2ft), while meat sitting on the ground could only be detected at distances of no more than two metres (7ft).   These results suggest that a fox's sense of smell is rather limited, but in his The Red Fox, H. G. Lloyd argues that the studies, which used fresh meat, might yield different results if they were conducted with decaying flesh (given that foxes are well known to scavenge).   Foxes are also known to possess an Vomeronasal Organ (sometimes referred to as 'Jacobson's Organ'), which is composed of tissue very similar to that found in the nasal lining and opens into the roof of the mouth; most mammals possess this organ and it appears to play a role in scent (especially pheromone) detection.   Ultimately, field observations suggest that foxes have a very keen sense of smell and that scent plays an important role in their day-to-day lives.

A characteristic of mammals is the presence of fur/hair, one function of which is to help maintain the body temperature.   However, some types of hair can also have a tactile (touch) function, allowing their owner to feel their way around.   Foxes have specialized -- tough, inert matrix without nerves -- hairs known as vibrissae, or "whiskers", on their muzzles (the longest of which grow to about 11cm) and forelegs (around the carpal or 'wrist' joint), which are associated with special nerve cells that are extremely sensitive to any contact (if you brush against a pet dog or cat's whiskers, you'll notice them sharply turn their face away).   Studies of cat whiskers have found that the part of the brain that receives information from the vibrissae has a very similar structure to the visual cortex -- some authors have suggested that the same it true of foxes -- implying that it may help the animal build up a visual image of its surroundings, although they don't 'see' with their whiskers per se.   It has also been demonstrated that, again in cats, when a prey item is too close for the animal to focus on it, the vibrissae are manoeuvred around the object so the cat knows where to bite.   Vibrissae are also present on the pads of the feet and probably play a role in allowing foxes to navigate their way along thin fences and through the branches of trees.   Overall, the vibrissae provide very detailed information on the objects that they touch as well as on air movements.

Coupled with their impressive senses, foxes also have a decent turn of speed and their relatively longer hind legs give them the propulsive force to achieve impressive jumps.   In a 1968 paper to the journal Saugetierkunde Mitteilungen, German mammalogist Theodor Haltenorth and Italian FAO biologist H. Roth report a top speed of 48 km/h (30 mph) and a maximum vertical jumping height from standing of 2m (7ft) for Red foxes.

Distribution & Habitat: The Red fox is the most widespread of all wild canids (indeed, all members of the Carnivora), covering some 70 million sq-km (~27 million sq-mi); found in rural and urban habitats throughout almost the entire Northern Hemisphere and isolated parts of the Southern Hemisphere.   They're found in the UK and Europe east through Russia, Kazakstan, Iraq, Iran, Pakistan into northern India, China and Thailand to Japan.   To the west, Red foxes can be found in the northern and eastern USA, north through Canada and Alaska to Baffin Island.   They are conspicuously absent from many of the Arctic islands including Greenland and Iceland.   Foxes are also absent from most of northern Australia, although they're now prevalent in the south, after their introduction for hunting purposes in 1868.   They also do not appear to have spread far into the African continent, although their are reports from the northern fringes and down into Egypt and northern Sudan, along the course of the River Nile.   They are also absent from much of the southern and western USA, Mexico and most of the Southern Hemisphere.   Introductions to islands have met with mixed success and in some cases (e.g. Isle of Man, UK) they are no longer present.   Red Foxes have been found at most altitudes, from sea level up to 3000m (almost 10,000 ft).

Red foxes are at home in most settings; from the heart of our towns and cities to the 'frozen wastes' of the Arctic, where their range may overlap with the Arctic fox (Vulpes lagopus).   Where this overlap occurs, Red foxes seem to be dominant to (and will kill) Arctic foxes, although as might be expected, Arctic foxes are superiorly adapted to life in the Arctic (far more so than the Red fox) and so the range of Vulpes vulpes in exceptionally cold climates is limited.   Although most people encounter foxes in urban settings, the general perception of 'natural' habitat is a dry mixed landscape consisting of scrub, woodland and farmland.   However, foxes are also abundant in plantations, on moorland, in mountains (above the treeline), coastal dunes and even deserts.

Longevity: Red foxes tend to live between two and six years, with the upper limit for wild individuals widely considered to be about eight years.   Some reports have suggested that foxes may survive to ten years; captivity increases the lifespan considerably (15 years being the record).

Phil Baker at Bristol University found fox longevity is related to social status and that urban fox longevity can be significantly reduced compared to their rural counterparts (two years compared with four years).   Dr. Baker calculated that the average age for a dominant fox was about 4 ¹/₂ years, while subordinates only lived for an average of just over two years.   The difference in average longevity that Dr Baker observed between rural and urban animals is primarily attributable to cars; thousands of foxes are killed each year on Britain's roads.   Diseases such as mange and rabies (see Q&A) can also significantly curtail longevity in both rural and urban populations.   It has been estimated that only 3% of Britain’s urban foxes survived the sarcoptic mange outbreak of the 1990s; 90% of Bristol’s urban foxes were wiped out by mange in 1994.   Other illnesses that can reduce fox longevity include exudative pleurisy (a lung infection), which kill adult and young foxes, especially during the winter months.

Ageing a fox is no simple task; the grey muzzle and coarse coat that we generally associate with old dogs don't necessarily indicate an old fox.   The only sure way to estimate the age of a fox is to look at its teeth; fox teeth wear down at a roughly even rate and the amount of wear on the incisor teeth can be used to age the individual.   (Back to Menu)  

Sexing: Sexing individuals from a distance is something of an acquired skill, because there is very little sexual dimorphism in Red foxes (i.e. the males and females look very similar).   As in many (although certainly not all) mammal species, adult males are usually larger than females: between  67 – 72 cm and 62 – 68 cm, respectively.   Similarly, the skull morphology is different: males tend to have broader heads with longer, narrower snouts than females.   However, at close quarters, the most accurate method is to look for a penis sheath, or (during cub-rearing) swollen teats.   Female foxes are referred to as "vixens", while males are called "dogs". (Back to Menu)

Activity: Predominantly crepuscularily-nocturnal (active at dusk, night and dawn).   They can be seen diurnally (during the daytime) lying-up in thick vegetation, patrolling territories or (especially when they have cubs) hunting.   Diurnal activity is more common in (although by no means unique to) areas with low levels of human disturbance.   Good climbers, foxes will sometimes use low branches of trees as a daytime resting place, providing a vantage point.   Much of the literature says that, in urban environments, foxes tend not to become active until after midnight.   In my experience, foxes can be seen at almost any time of the day.   I have seen foxes in my gardens from around 8pm to 10am.   I've never spotted them in urban settings in the middle of the day, but I know many people who have.

In Bristol, tracking studies showed that the foxes were active for about eight hours per night, during which they covered some 7.7km (about 5 mi).   Activity varies with season and individually among foxes; they tend to travel further during summer (finding food for cubs) and winter (looking for mates) than in the spring or autumn.   Cubs are active for roughly the same length of time as adults (depending on age), but tend not to venture far from the earth during May and June, increasing their area of activity from July onwards and following adults on forages.   Foxes are active year-round and do not hibernate. (Back to Menu)

Dens/Earths: It is not uncommon for a group of foxes to have more than one earth in their territory.   Often a fox family will have a natal (breeding) earth and one–or–more smaller earths where they spend time outside of the breeding season.   The natal earth is the largest, with more than one entrance/exit and a chamber up to three metres below the ground.   The 'standard' earths are usually smaller, with a single opening connecting the chamber to the outside world by a tunnel up to ten metres long; the entrance may be marked with scat (left).   A study published in the Southwestern Naturalist back in 2000 found that Swift Fox (Vulpes velox) earths and earth sites on the Great Plains were pretty much identical with respect to size, number, direction and shape of openings, distance between openings, dimensions of tailings, slope of site, surface roughness and ruggedness of site, surrounding vegetation and soil type.   Although there are invariably some features that foxes look for when selecting an earth or potential earth site, they do seem to be capable of exploiting resources in most available habitats.

Urban foxes will readily make dens under garden sheds, in banks of earth (e.g. on railway embankments), and even under the floorboards of occupied houses, or in trees!   Unlike badgers, foxes do not use bedding material.

In their 1996 book, Badgers, Ernest Neal and Chris Cheeseman note that, although foxes occasionally dig their own dens -- often extending disused rabbit burrows -- they are typically "lazy diggers and much prefer to use badger setts if available".   Moreover, Neal and Cheeseman point out that in the Netherlands, Switzerland Denmark and Germany "it is the rule for foxes and badgers to live in the same sett" - it has been postulated that this reflects a lack of suitable habitat in these countries.   Under most circumstances where foxes are found in badger dwellings, these setts will be unoccupied although, if the sett is sufficiently spacious foxes may share accommodation with the badgers; foxes use one part, while badgers use another.   This relationship seems to work well and the badgers -- despite apparently being dominant over the foxes (they can apparently evict the them at will) -- tolerate foxes for most of the year.   However, this situation can change when cubs are present.   Intriguingly, whomever has cubs seems to get movement rights.   One example of this comes from a wildlife park in Avon, where expansion of an earth by foxes had caused the amalgamation of the foxes' earth and a nearby badger sett.   In this case, foxes were only dominant when they had cubs.   When badgers have cubs underground, any encroachment by a fox typically meets with strong aggression on the part of the sow. (Back to Menu)

Territory: The size of an animal's territory is largely determined by the distribution of resources across the area, while group size is determined by the average level of resources.   Consequently, territory size and group size may vary independently.

There is tremendous variation in home ranges among foxes.   Rural foxes commonly have territories between two and six square-kilometres (200 to 600 hectares), extending up to 40 km² (4000 ha) in the Scottish Highlands, where resources are sparsely distributed.

Urban foxes tend to forage over smaller areas, about half a sq-km (one-quarter of a square-mile).   The territory is usually composed of two 'sub-territories'; a smaller (roughly 4 km²) area exists around the earth -- which is defended against intruding foxes -- and the remaining region that a fox will range over, which may overlap with other fox territories.   In urban settings, radio tracking studies have demonstrated that not only can fox territories be arranged in a honeycomb pattern, but they also have a tendency of drifting.   A series of papers by Dr. Patrick Doncaster (Southampton University) and Prof. David Macdonald (Oxford University) during the early 1990s report that territories in the suburbs of Oxford appear spatially stable, while those in the city centre continually drifted in location.   Moreover, the biologists discovered that the territories drift in synchrony with each other and, although the territories were reasonably small (averaging only 39 hectares - 0.39 km² or 0.15 mi²) they were constant in size.   One particular study by Doncaster and Macdonald in 1991 uncovered a hexagonal pattern of city ranges that moved (or 'drifted') at a rate of 38ha every 13 months.   In other words, the network of territories shifted by one territory size every year.   It seems that as one part of the territory is yielded by fox "A", this area is taken over by one of its neighbours (fox "B"); but fox B doesn't range over a larger area, rather it relinquishes a similar sized area of its own territory.   Doncaster and Macdonald suggest that: "the ultimate explanation for drifting is that the city environment is inherently disturbed, by pedestrian and road traffic, habitat management and construction and demolition work."   Indeed, the tracking of foxes in Oxford and Bristol has shown that conspicuous landmarks (i.e. hedgerows, roads, walls etc) are often used as territory boundaries, so it is easy to see how the continual state of development in our major cities could lead to the continual fluctuation of fox territories.

Season appears to have a prominent impact on the area over which a fox will travel.   In winter, American Red foxes extend their range from three kilometres (2 miles) to between eight and sixteen kilometres (5 to 10 miles).   During the breeding season, males are known to move over areas larger than their home territory, presumably looking for mates, while females typically spend a greater proportion of their time at the periphery of their territories (again, this probably facilitates mate-finding).   However, seasonal changes to ranging may also be more subtle that searching for a mate.

In a 1990 paper to the Journal of Animal Ecology, Bristol University biologists Tom Woollard and Stephen Harris report on the behaviour and movements of dispersing and non-dispersing foxes.   Dispersing foxes making exploratory forays into newly-charted areas moved at top speeds significantly higher than were observed in non-dispersing individuals: 92.4 metres (303ft) per minute and 42 m (138ft) min^-1 (or 3.4 & 1.5mph), respectively.   Between March and October, dispersing foxes utilised more daytime 'lying-up' (i.e. resting) sites than their non-dispersing conspecifics; the nine dispersing animals used 96 resting places over 387 days, while the seven non-dispersing individuals used only 56 over 510 days.   Dispersing animals  also tended to use more resting sites outside of their core activity area than non-dispersing ones (56% and 44%, respectively).   The biologists also found that, on exploratory nights, dispersing foxes spent little time resting or foraging and most of their time moving over new ground.  Consequently, dispersing animals covered much greater distances during these nights than on non-exploratory nights - it seems that rather than making trips outside their home range looking for food (which has been suggested by previous authors), these foxes were simply exploring new areas and trying to cover as much ground as possible.   Although there are obvious benefits to dispersing -- less competition for food, release from any potential breeding suppression etc. -- there are also some significant costs involved.   Earlier work by Stephen Harris on Bristol's foxes found that non-dispersing foxes typically lived five months longer than dispersing ones.

Territory holders generally have little to gain from fighting other territory holders and so the neighbours adopt passive actions (predominantly scent marking) to maintain boundaries - some foxes may even go out of their way to avoid meeting their neighbours.   Territory boundaries are marked with scent: either urine -- although scent marking only accounts for about 12% of a fox's urinating behaviour -- or a hormonal secretion from anal glands located either side of the anus and scent glands around the mouth (around the lips and angle of the jaw) or between the toes.   A study by Eric Albone found "volatile terpenes" in the anal gland secretion of foxes.   In chemistry, if something is said to be 'volatile', it means that it is capable of readily changing from a solid or liquid into a gas/vapour.   In this instance, the terpenes -- which are a type of lipid -- move from the liquid of the secretion into a vapour, which other foxes (and apparently some humans) can detect.   A 1980 study of the bacterial microflora in Red fox anal sacs by microbiologists at Bristol University, recorded 18 species of anaerobic bacteria from six genera (including Clostridium and Eubacterium); several of the species are well known to produce substantial quantities of fatty acids.   The authors found bacterial levels of between one billion and ten billions per millilitre of anal sac fluid.   Scent glands are also present between the toes, on the forelegs and on the face.  

Foxes, like other canids, possess an additional scent gland located on the ventral (top) surface of their tail (often characterised by a patch of dark fur).   This gland is roughly oval in shape, measures about 25 by 7.5 mm (1 x 0.3 in), is positioned about one-third of the way down the tail -- about 5 or 6 cm (about 2 to 2.3 in) from the fox end -- and is referred to as the supracaudal (or violet) gland.   The gland is composed of tube-shaped sweat glands and massively developed sebaceous glands.   In his 1940 histological examination of the supracaudal gland, German scientist J Schaffer, concluded that the secretions may be expelled from the gland by contraction of the muscles at the base of the hairs.   Studies on the chemical composition of the gland and its secretions, carried out by Eric Albone (now at Clifton Scientific in the UK) during the 1970s, found that the gland may play an important role in the metabolism -- and possibly even the production -- of steroids.   In one particular (1976) study, Dr Albone and Peter Flood (Bristol University) found that the gland has "naturally fluorescent photolabile sebum constituents", which basically means that it glows, although the light is hidden from our eyes -- and probably the fox -- by the unfavourable UV/Visible flux ratio in the atmosphere.   The origin of this glow is unknown, although Albone and Flood speculate that it may be related to the presence of carotenoids (a family of red and yellow pigments found in plants and animals) in the gland secretion.  

The function of the supracaudal gland is still somewhat unclear, but it does seem to be involved in intersexual communcation - the gland of male foxes seems to be more active during the breeding season.   The gland also seems to play a role in intraspecific communication – when foxes meet they will often sniff one-another’s violet glands.   Indeed, in a 1971 paper, Michael Fox found that the secretory activity of this gland increased after group play in the Arctic fox (Alopex lagopus).   Badgers are also known to possess a violet gland, which is apparently used for similar (if not identical) purposes to the supracaudal gland of foxes.   The violet gland of the European badger (Meles meles) produces a lipid-rich (high fat content) secretion that is used to mark both their environment and conspecifics (see Badgers for a more detailed treatment of this).

Abundance: Fox abundance varies considerably in relation to habitat and the distribution of resources.   On average, fox population density is about one family per square kilometre in farmland, while the maximum proven density was five families (with 30 adults) per square kilometre in a suburban setting.   The lowest fox population densities are found in upland areas (e.g. Scottish Highlands), where there may be only one fox in as many as 40 square kilometres.   Abundance of foxes in the rural mountainous areas of Switzerland are reported to be three per sq-km, while those for Arctic tundra are closer to one per 10 sq-km.   Population estimates for Red foxes in the UK are given below.

The number of foxes in a given area is known to change according to season.   A study of Red foxes on open farmland in western Poland found that the average fox density (estimated by spotlight counts) was about one individual per square-kilometre in the spring, and 1.63 foxes per kilometre-square in early winter.   The study also found that the average breeding population density was 61% of the average total spring density, suggesting the presence of a 'surplus' of individuals in the population.   A similar study, also in Poland, found that the overlap between fox families occupying large ranges was greater than that between foxes living in small ranges.   Thus, it would seem that there is a different pattern of space use and differences in the defence of territory by foxes inhabiting large ranges and those in small areas.

We now also know that virulent disease affects the territory size and ranging behaviour of foxes.   Since the outbreak of mange in Bristol during 1994, there are fewer foxes, each with larger territories than before mange arrived; Bristol's fox population was reduced by 95% in two years, but home range increased 600% after the outbreak, from 20 to 140 ha (0.2 - 1.4 km², or 5 - 346 acres).    Interestingly, although the overall size of each territory increased, the distance travelled by the foxes didn't increase, which you might expect, given that the fox is now defending a larger patch.   Similarly, the foxes were active for the same length of time as they were before the outbreak.   It seems that the the foxes reduced the amount of time they spent travelling around their territory in favour of spending more time at the periphery, resulting in some of the inner parts of the territory never being visited.   One study by Phil Baker and his colleagues published in the journal Animal Behaviour in 2000, reports that as the fox population density declined -- through mange-induced mortality -- the surviving animals consistently increased the area over which they ranged, absorbing extra territory as competitors in neighbouring groups died.   Intriguingly, Baker and his co-workers found that this increase in territory size did not represent a dramatic increase in energy expenditure for the foxes.   Where the biologists recorded an 11-fold increase in territory size, only a 16% increase in energy expenditure was incurred.   However, Dr Baker and his co-workers noted that despite the large-scale die-off, the foxes didn't increase their territory until after the all members of the neighbouring group had died.   Thus, it would appear that the main cost for these foxes was the possibility of serious injury or death from attempting to overthrow peripheral territory-holders.

It should be noted that, although territoriality is well known in Red foxes throughout most of their range, it is not observed in every population.   Between January 1989 and April 1992 (with an intermission during the Gulf War), a team of biologists from the Wildlife Conservation Research Unit in Oxford lead by David Macdonald conducted a detailed study on the Red foxes (Vulpes vulpes arabica) inhabiting the biological reserve of Thumamah in the great sand deserts of Saudi Arabia.    Over a period of three years, 41 foxes (21 males and 20 females) were fitted with radio collars and their movements tracked.   The tracking revealed an average home range of 676 ha (6.76 km², 2.6mi² or about 1,670 acres) that didn't vary according to sex or season.   The most interesting discovery was that territoriality was not observed; instead they observed loose-knit groupings.   Females shared territory more readily than males.   The biologists suggest that this situation arises because it helps the foxes, which are smaller in size compared to populations elsewhere (i.e. about half the size of those in the UK), to survive in an extremely harsh environment with a spatially and temporally sparse food supply.  Additionally, not all foxes hold a territory.   Indeed, it is estimated that some 15% of adult Red foxes are itinerant (i.e. they wander with no fixed home range).   (Back to Menu)  

Predators: Foxes typically have very few true predators, because predators rarely eat other predators.   Most cases where other larger carnivores kill foxes it is typically done to remove a competitor.   Nonetheless, in some instances -- especially where cubs are taken -- the carcass may be consumed.

In the UK foxes have only one natural predator, the Golden eagle (Aquila chrysaetos), which is restricted to the Highlands of Scotland and isolated patches of northern England (e.g. Cumbria).   According to the Royal Society for the Protection of Birds (RSPB), Golden eagles can lift a maximum of four or five kilograms (9 – 11 lbs) – adult male foxes average around 7kg (15 ½ lbs), while females average 5 ½ kg (12 lbs), suggesting that only young foxes are taken by these raptors.   The occasional fox is dispatched by a hunting party or is shot by landowners, while a vast majority die on Britain’s roads.   In Europe, wolves (Canis lupus) and lynx (Lynx lynx) will take foxes if the opportunity arises.   Long-tailed weasels (Mustela frenata), ermine (Mustela erminea), skunks (Mephitis mephitis), mink (Mustela vison) and snakes may take very young fox cubs in the US, while owls (Strigiformes), hawks (Accipitriformes), coyotes (Canis latrans), wolves, and bobcats (Lynx rufus) take older pups and (in the case of wolves) occasionally adults.

Although not technically a "predator", foxes (and especially fox cubs) may occasionally fall foul of badgers (Meles meles).   In North Wales back during 1958, for example, Abel James witnessed a standoff between a vixen and a badger on a cliff edge.   Mr James notes that the fox and badger were snarling at each other when the vixen, finding herself trapped, tried to leap over her opponent.   Unfortunately for the vixen, the badger reared up and seized her leg and the two proceeded to role around the cliff top locked in combat.   The pair rolled towards, and then over, the cliff edge - by the time Mr James made it down the cliff, both were dead.   In their book Badgers, Ernest Neal and Chris Cheeseman report several instances where badgers and foxes were witnessed to be embroiled in fierce combat.   Similarly, in his 1923 book, The Badger Afield and Underground, H. Mortimer Batten describes several examples of badgers killing fox cubs.   However, perhaps the most interesting account comes from E. Clay in a communication to The Countryman.   Mr Clay describes hearing screams coming from a dense blackberry bush while watching fox cubs play on a hillside near his home in Devon .   Upon moving closer, Mr Clay discovered one of the fox cubs lying there with one of its back feet bitten off, its hind quarters apparently paralysed and skin torn on its shoulders.   Mr Clay then saw the head and forequarters of a large badger appear, which gripped the cub by the throat and dragged it down a nearby hole.   This account is interesting because it bears considerable resemblance to a feeding-motivated attack - rather than a defensive strike.   Obviously Mr Clay was unable to follow the badger down the hole, and it is unknown whether the fox cub was consumed.   It should be noted that incidences of badgers killing foxes (and indeed, foxes killing badgers) are far from commonplace, and the two species are normally indifferent to each other's presence. (Back to Menu)

Food & Feeding: The foxes studied by J David Henry in the boreal forests of northern Canada spent about 35% of their waking day (about 5 hours) searching for food I suspect one could fill an entire book with the different items that foxes have been known to consume.   One study on Red foxes in Missouri recorded 34 different mammal species, 14 species of bird, 15 families of insects and 21 species of plants in their diet.   In a paper to the Journal of Arid Environments in 2004, Daniel Lenain at the National Wildlife Research Center in Saudi Arabia and two colleagues report on the diet of Arabian Red foxes (Vulpes vulpes arabica).   Dr Lenain and his co-workers found that "other invertebrates" -- their category for all those bugs and worms that weren't beetles -- were the major component of their diet, present in 85% of fox scats collected.   Small mammal remains were the second most abundant, found in almost 80% of droppings.   Vegetation and seeds were found in 36% of scats, while both bird and reptile remains appeared in 2.4%.  Where foxes opt for mammalian or avian prey, they tend to take animals up to about 3.5kg (almost 8 lbs.) in weight.   (Photo: Eggs seem to be highly-prized by foxes -- presumably for their protein, fats & cholesterol -- and they will often carry them away to cache for later use.)

A study on the diet of badgers and foxes on agricultural land in the Western PO Plain of northwest Italy by Lucy Canova and Paola Rosa at the Universita di Pavia, found that wild rabbits comprised the bulk of prey items consumed, while mammals collectively accounted for more than 60% of the diet.   Vegetables (especially corn, Zea mays) and insects (esp. beetles, Coleoptera) were important secondary diet components.   Their observation that mammals are important in the diet of foxes is one that is congruent with dietetic studies of Red foxes across much of their range.

Sufficed to say, foxes are extraordinarily opportunistic, omnivorous feeders that feed predominantly on small mammals -- especially rodents (rats, mice, voles and the occasional squirrel) and lagomorphs (rabbits & hares) --, birds, insects (especially beetles during the summer months), earthworms, carrion, fruit and berries (in the autumn, especially blackberries).   Foxes will also take fish and eggs if they are available.   Those living in coastal regions will search the beach and peripheral environs for shore crabs, dead fish and seabirds.   A substantial part of a newly weaned fox cub’s diet is composed of oligochaetes (earthworms) and foxes also seem to have a penchant for rat-tailed maggots, hoverfly larvae (both found in stagnant water) and crane flies (daddy-longlegs).      Dead or dying foxes are occasionally cannibalized and foxes will eat grasses -- such as Cock's Foot (Dactylis glomerata) -- which may serve to remove tapeworms.

A study for the Game Conservancy Trust in Inverness (Scotland) conducted between 1992 and 1996 found that Red foxes from moorland in south-west Scotland fed on rodents, game birds, lagomorphs (rabbits and hares), carrion and insects.   Rodents were the most frequently occurring food type in each habitat, although it seemed that foxes switched to game birds in years, or habitats, where rodents were uncommon.   Indeed, various studies on the feeding patterns of foxes have indicated that they distribute their feeding effort in different areas in a manner predicted by the Optimal Foraging Theory (OFT).   OFT predicts that an animal has an innate capacity to modify its feeding and hunting behaviour to get the best returns (in terms of energy) for its effort.   There are two primary branches of OFT: energy maximization (i.e. animals seek high energy foods) and number maximization (i.e. animals feed on whatever species is most locally abundant).   The data available indicate that foxes lean more towards number maximization than energy maximization.  

Although foxes are known to switch their diet in response to prey population changes -- such that they feed on whatever is most abundant locally -- the success rate with which foxes are able to capture prey species is known to vary considerably.   During his numerous wanders around the boreal forests of Canada observing Red foxes, the eminent ecologist J David Henry observed 434 completed hunts (i.e. where some attempt was made by the fox to pin and bite the prey) by 22 foxes.   Dr Henry noted that 139 (32%) of these hunts were successful and that there was an interesting variability between the success of the fox and the type of prey.   Foxes successfully caught insects 82% of the time, mammals 23% of the time, and birds only 2% of the time.   It is tempting to suggest that this success rate is probably related to maturity and, hence, experience.

Dr Henry also looked at the pouncing aspect of the fox's predatory behaviour.   Foxes often pounce on small rodents, pinning them to the ground before biting them.   Using video footage that he had shot of several pounces, Dr Henry was able to calculate that the foxes have a 'take off' angle of 40^o (give or take about 6^o).   This is interesting because conventional physics states that the optimal take-off angle for a missile (i.e. the angle at which it has to leave the ground in order to travel the greatest possible distance) is 45^o, so the fox is pretty close to optimal.   Dr Henry suggests that foxes may take off at a slightly suboptimal angle because, were they to pounce at 45^o, they may become too conspicuous to their potential prey.   To my mind it seems reasonable that a fox might also adjust its 'take-off' angle in accordance with its distance from its intended meal - optimal distance is no good if you sail straight over the top of your dinner!

Foxes have a rather notorious reputation as predators of hedgehogs and some authors have implied an impact in controlling hedgehog populations.   In Urban Foxes, Stephen Harris and Phil Baker write that there has been a noticeable increase in Bristol's hedgehog population since the outbreak of mange (which drastically reduced fox numbers) in the mid-1990s.   One intriguing 'story' about foxes tells of their rather unique way of getting around the spines of hedgehogs.   This particular method involves the fox urinating on the curled up hedgehog, which (understandably) causes the hedgehog to unroll and the fox can then eat it.   I came across several reports of this behaviour when I was researching this article and, until recently, believed that they were merely stories.   However, I now know of a retired gamekeeper -- who used to work on a private reserve near Ripon in North Yorkshire -- who witnessed this behaviour on several occasions.   The subject of foxes as predators of hedgehogs is covered in more detail in the Q/A section.

In urban areas, foxes are known to raid dustbins for scraps (although less frequently than most people realise), and will occasionally breach smallholding security to gain access to chickens and possibly pet rabbits or guinea pigs.   Urban foxes may also raid bird tables for crusts of bread, or feed on worms surfacing on lawns during wet weather.  According to the DEFRA (2002) report Urban Foxes in Britain about 33% (one-third) of an urban fox’s diet is either scavenged or deliberately provided by householders.

A study by Stephen Harris published in the journal Mammal Review in 1981 looked at scavenged items found in the stomachs of 571 foxes caught in London.  The paper showed that meat and bones from joints and carcasses composed 18.4% of the diets.   Bread, dried fruit and potato peelings were also present, representing 3.1%, 2.4% and 1.6% of the diet respectively.   Another study by a team led by Patrick Doncaster, published in the Journal of Mammalogy  during 1990, looked at the feeding ecology of foxes in Oxford (UK).   Dr Doncaster and his team found that at some sites where food was provided by residents, scavenging -- which accounted for some 60% of the foxes' food sources -- foxes were highly selective, discarding some edible items in preference for others.   Dr Harris and Dr Doncaster both reported that no single species was dominant in the fox’s diet.

In a 2004 paper to the journal Mammalian Biology, a team at the University of Zurich report on the diet of foxes in the city of Zurich (Switzerland).   The biologists analysed the stomachs of 212 foxes and found that scavenge (primarily scavenged meat) and cultivated crops (especially apples, plums and cherries) were the primary components of the diet, comprising nearly 62% of stomach contents - furthermore, almost 60% of the stomachs examined mainly or exclusively contained one of these three items.   Rodents and birds were also present, occurring in 26% and 24% of stomachs, respectively.   Insects (17.5% of stomachs), pets or domestic stock (10.4%), pet food (6.1%) and bird seed (9.4% - found from January to March only), were also found.   Even in the 'urban zone' of the study, "natural food" (namely birds and wild mammals) still contributed 20% of the foxes' diet.   Additionally, the biologists didn't witness foxes exploiting bin liners regularly or systematically, suggesting that they were opting for less exposed food sources.

Red foxes cache (store) excess food; there is a tendency towards Scatter Caching , rather than Larder Caching (i.e. they tend to spread their food around, rather than putting it all in a single hole).   Caching is a behaviour often observed during periods of high food abundance and, in some species, it can be associated with a phenomenon called “Surplus Killing”.   Surplus killing, as the name suggests, is the practice of killing more than you can consume at the time – a good example of this is the damage a fox can do in a chicken run.   If a fox gets into a chicken pen, it will often kill all accessible fowl, and appear to leave them just lying around – part of the reason many livestock holders despise foxes.   There have been several theories put forward to explain why foxes do this.   One of the most oft cited ideas is that the fox stumbles across a bountiful food source -- in the wild predators rarely know where the next meal is coming from -- and it decides to best exploit this reserve.   As such, the fox kills all the chickens and then begins the task of removing and burying them.   The fox can only carry one chicken at a time, making the caching process slow.   In many cases, the farmer comes out to investigate the commotion before the fox has had chance to clear the hen house.   Another theory is that of "Pathological Killing", where a predator kills restrained prey because it's unsure how to deal with prey that doesn't run away.   I deal with this idea and the foxes kill for 'sport' or 'fun' in my Q/A section.

Chickens and pets tend to be the most commonly reported livestock 'victims' of fox predation, although there is evidence to suggest foxes will also take lambs and there are reports of foxes carrying away piglets.   Conventionally, biologists have considered that foxes would only take still-born lambs and scavenge the afterbirth.   However, it is now known that, although foxes probably do take still-borns and afterbirth, they will also kill newborn lambs.  

In his 1940 classic I Bought A Mountain, Thomas Firbank says that a considerable number of lambs are killed by foxes in the hilly grazing land around Snowdonia, although the published evidence is rather sparse.   In his 1984 contribution to the Journal of Applied Ecology, Ray Hewson at Aberdeen University studied the diets of foxes in two areas of western Scotland.   Dr Hewson found that foxes in these areas fed primarily on sheep carrion and field voles, supplementing their diet by killing about 1.3% of the lambs estimated to have been born in the area during 1976.   Dr Hewson provided minimum values for lambs killed by of 1.8%, 0.8% and 0.6% of the lambs estimated to have been born in 1977, 1978 and 1979 respectively.   The paper reports that foxes (and eagles) killed lambs one to five days old and in apparently good condition; foxes took lambs up to 10kg in weight, while eagles only took lambs as heavy as 6kg.   Dr Hewson observed several other trends -- such as foxes consuming more carrion in the first half of the year and more field voles in the second -- and went so far as to speculate that, with regards to lamb susceptibility to foxes, lambs of ewes breeding for the first time (compared to those of older ewes) may have been more vulnerable owing to poorer maternal care.

More recently, Rebecca Moberly and four of her colleagues at Bristol University surveyed sheep farmers across the UK about the levels of fox predation on lambs.   The results of their questionnaire -- published in the journal Wildlife Research in 2003 -- showed that, although individual losses were low, the range of "perceived" losses to foxes was high: 0.0008 to 0.26 lambs per ewe.   The paper also reports that fox predation was more likely to have occurred on larger farms and that 59% of those who responded to the survey had reputedly lost at least one lamb at their most recent lambing.   Moreover, the researchers found that indoor lambing was an important preventative measure against fox predation

In Australia, Carolyn Greentree and colleagues at the Vertebrate Pest Research Unit in New South Wales found that fox predation was the probable cause of lamb death for a minimum of 0.8% and a maximum of 5.3% of the 1321 lamb carcasses they examined.   In their paper to the Journal of Applied Ecology, the biologists report that fox control three times per year reduced the maximum percentage of lamb carcasses attributed to foxes from 10% to just fewer than 4%.   Unfortunately, the same data for predation by foxes on piglets does not exist and, although foxes have been reported to carry piglets away from farms, such accounts are largely anecdotal and it is not clear whether the fox took a live piglet or scavenged a dead one.

The amount of food required to sustain a fox’s metabolism seems to vary with season.   A study of Red foxes in New South Wales (Australia) reported that male body fat reserves peaked at 13% of body mass in June (just prior to breeding) and female body fat peaked at 16% in July during gestation.   Body fat reserves were found to decrease rapidly in both sexes from September through to November, reaching an average of three to four percent by the time of weaning.   The researchers also found low body protein content from August to November (corresponding to a decline in fat reserves), suggesting that the foxes accumulate fat and protein reserves during the non-reproductive seasons and then deplete them during the reproductive period.

In a study on the Swift fox (Vulpes velox – a North American relative of the Red fox) published in 1995, Ken Weagle and Clio Smeeton found that the ration of food (averaged over a year) was 110g of meat per fox per day; equivalent to four small birds each day.   A report by a team at the Central Science Laboratory in York (UK) published during 2002, estimated the daily food intake of Red foxes to be between 520 and 569 grams per day for an animal weighing 5.7kg – equivalent to about 10% of their bodyweight per day.   In his book Red Fox: The Catlike Canine, Dr Henry notes that foxes can survive on only one pound (about 454g) of meat per day.   Indeed, foxes have proportionally small stomachs compared with other dogs and the maximum Dr Henry ever observed a fox to consume in a single sitting was about a pound and a half.

From an energetic perspective, Glen Saunders (now at the Vertebrate Pest Research Unit in New South Wales) and his colleagues calculated that the amount of energy required to support a pair of foxes is 28MJ -- equivalent to about 6,700 kcal -- per week.   Broken down into the major food groups, this is equivalent to each fox consuming about 950 grams of either carbohydrate or protein or 393 grams of fat each week, although in reality their diet would be a mixture of these.   In captivity, energy requirement estimates have been higher; adult foxes have been found to require about 507kJ (ca. 121 kcal) for every kilogram of bodyweight per day, while cubs (13 to 14 weeks old) require 934kJ (ca. 223 kcal).   Thus, for your 'average' adult fox, this equates to about 3MJ (716 kcal) per day, or 21MJ (5,000 kcal) per week each.   Perhaps the fact that the foxes were captive signifies rehabilitation, which may explain the increased energy requirements.

The relationship between size and energy requirement is based on the interaction between the animal's weight and surface area (across which a considerable amount of energy is lost as heat).   Using a simple veterinary formula for calculating the Resting Energy Requirements (RER) of animals weighing more than two kilos, we arrive at an energy requirement of about 1MJ (250 kcal) per day for a six kilo fox.   Multiplying up, we are presented with a need for this fox to obtain at least 7.3 MJ (1,750 kcal) per week - bear in mind that foxes aren't in a constant state of rest and consequently it is quite possible that the active energy values are twice the resting rates and are, therefore, in line with those calculated by Dr Saunders and his colleagues.   At any rate, this gives us an insight into how urban environments are generally able to support larger fox groups than rural ones.    In their 2000 study, Dr Baker and his co-workers found that the food put out by householders in Bristol represented about 40MJ (9,554 kcal) per week, nearly three-times the amount required by a single fox!  (Back to Menu)  

Breeding Biology: In the UK, the breeding season for Red foxes runs from late December to February and the female’s receptive period is short: between one and three days.   Vixens begin looking for breeding dens in early February, which will be occupied until at least June.   The earth will often have more than one entrance/exit, face south and have a good view - a vixen may dig her own earth or expand an abandoned one.   During the mating season, courting foxes may -- although not necessarily -- travel and hunt together for about three weeks; towards the end of the mating season a given pair may mate several times.   During the breeding season males can experience a six-fold increase in testis size and -- like other dogs, cats, hedgehogs, bats, rodents and many other species -- foxes have a bony structure in the penis called a baculum.  The baculum is a heterotrophic skeletal element -- in other words, it is dissociated from the rest of the skeleton -- that serves to maintain an erection during intercourse.   As tissue surrounding the baculum engorges with blood, the mating pair may become locked (or tied) together for between two minutes and more than an hour (although such 'ties' do not always happen).   Tracking studies in Bristol have revealed that, after the dominant vixen has ended her oestrus, the male rapidly expands his range (in many instances more than doubling the distance over which he travels) to increase the likelihood of encountering more vixens.

A study in the Pisa province of central Italy published in 1996 reports that vixens shed, on average, five ova, had 4 placental scars and produced 4 live embryos.   About 20% of the vixens studied were barren and heavier females produced more offspring than lighter ones (although this difference wasn't related the the amount of subcutaneous fat).   Ultimately, subcutaneous fat wasn't correlated with the rate of ovulation, the number of foetuses or the size of the litter.   The rate of foetal loss was higher in younger females than in adults (43% in yearlings, 17% in adults).   These results provide interesting reading because not only do they imply that Italian foxes have fewer ova, embryos and placental scars than those from America and Europe, but they also suggest that the reproductive output of these foxes wasn't limited by food, but by social modulation.   This is interesting because it has conventionally it has been considered that where several vixens coexist, one dominant female suppresses the reproduction of the others.   Whether the vixen does this by restricting subordinate access to food, or via some form of behavioural control (e.g. stress hormones may play a role in suppressing reproduction) was thought to vary geographically.   Indeed, in 1989 it was proposed that foxes at high latitudes are directly food-limited, while those to the south are socially regulated.   However, although in most circumstances only one litter will be born each year, under conditions of plenty, two or three litters are possible (indicating that some of the “helpers” may breed too).  

Another common belief was that foxes were monogamous (i.e. they only mated with their partner).   Recently, a study by Bristol University published in the journal Behavioural Ecology, uncovered mixed paternity in urban fox litters.   Monogamy was observed or assumed in only about half of all breeding attempts, while polyandry (i.e. females having more than one mate) and polygyny (i.e. males having more than one mate) were common.   When looking at litters of known paternity (i.e. the biologists could determine who the fathers were), 16 litters (38%) were found to be the product of more than one father, while when the litters of unknown paternity were included in the analysis, the number increased to 20 (69%).   It seems that anywhere up to seven different males may have been responsible for siring one litter (although the average was lower, with each litter sired by two dogs).   More interesting still, was the observation that of the 30 litters for which paternity could be determined, only six (20%) were sired by males from the same social group.   Both dominant and subordinate males and females mated with males within their social group, although the majority of cubs produced by subordinate females were sired by males outside their group.    While dominant and subordinate females produced cubs with dominant and subordinate males from other social groups, dominant vixens didn't produce cubs with subordinate males from their group.   Dominant individuals of both sexes reproduced at every breeding opportunity, while the subordinate individuals were only observed to reproduce at 40% (males) and 56% (females) of breeding opportunities.   Incest (i.e. mating with one's kin) was observed, but such occurrences are considered rare.   A related study by the same department of Bristol University found that some (about 20%) subordinate vixens will fall pregnant but will have very late-term abortions.   It seems that this is an evolutionary strategy that allows the vixens to 'keep their options open' so that, should something happen to the pregnant dominant vixen the subordinate vixen can step in with her own cubs.

The advantage of polyandry for the dog fox is that he spreads his genes around.   Considering that many (especially subordinate) males will only live long enough to breed once or twice, spreading the cubs around helps to ensure that at least some of them survive to pass on your genes.   For instance, were the dominant vixen to die before birth, a monogamous dog fox would have to wait a year before he could mate again.   Indeed, it is not only males that seem to avoid 'putting all their eggs in a single basket'.   While studying for his Ph.D at Bristol University, Piran White found that during the breeding season, vixens stayed closer to the territory boundaries than at other times of the year.   Dr White concluded that this behaviour increased the number of males that the vixen would encounter.

Interestingly, although males of many species are known to kill offspring from rival males while only tolerating their own (e.g. Ospreys, Pandion haliaetus, at Loch Garten in Abernethy Forest, Scotland), this seems rare in foxes.   The Bristol team observed that dominant males continued to provide food for the dominant vixen and her cubs, despite some of the cubs being the progeny of a rival male.   This suggests that male foxes are unable to discriminate between the cubs that are theirs and those which aren't.   Additionally, far from being disinterested in the cubs, the males are rather devoted fathers.   The culmination of this observed polyandry is linked with the patrimony of fox territory and it is not uncommon for successive generations to inherit the territories on which they were born.   Consequently, the promiscuity observed in these foxes is probably a strategy to counteract the problems that would arise from inbreeding (i.e. mating within one's family group).

During her pregnancy, the vixen is usually sustained by food provided by the dog fox -- who is excluded from the den during parturition -- and 'helpers'; post-parturition (after birth) the food parcels provided by the male and subordinates are used to feed the offspring.   It should be noted that, while subordinates are frequently observed within social groups, these so-called 'helpers' do not always seem to help!   In his book Foxwatching: In the Shadow of the Fox, Martin Hemmington talks about an incident where a vixen was confined to the earth with newborn cubs.   Unfortunately, her mate -- who had up until now been providing food for her -- was killed by a car.   The vixen was forced to go out looking for food (leaving the cubs alone).   Mr Hemmington notes that at no time did any of the other six subordinates in the group step in to take over the food provision, leading him to conjecture that perhaps these "aunties" only help with food gathering once the cubs have emerged.   Indeed, the current knowledge of how these helpers fit into the picture is still incomplete.   While some studies suggest that alloparental care (i.e. grooming, feeding and otherwise tending to someone else's cubs) is uncommon, others suggest it is frequent - indeed, where two females in a group breed, earths may apparently be shared and communal suckling has been observed.   Similarly, some studies suggest that alloparental care increases the survivorship of the cubs, other studies (one by the team at Bristol University) suggest that it doesn't!   Whatever the case, radio-tracking studies in Bristol have revealed that, within social groups where helpers do "help", dominant and subordinate foxes are equally involved with the provisioning of food for cubs.

The average litter size is four to six cubs -- also called pups -- in Europe, although as many as twelve foetuses have been found in a single female.   Indeed, the number of cubs in a litter is known to vary according to habitat, and specifically with the availability of food and shelter.   Experiments by a group of scientists based in Spain found that foxes in the “vegas” (their term for favourable habitat) had larger litter sizes (ca. 4 cubs per vixen) than those in the “steppe” (less favourable habitat), which produced an average of three cubs per vixen.   The vegas population also had a higher number of barren vixens (“helpers”) than the steppe: 19.3% and 1.7%, respectively.   Similar results were found by the team at Bristol University, who report in the book Urban Foxes that each litter in Bristol's urban areas (which are generally considered favourable habitat with regards to food and shelter) consisted of an average of 4.75 pups.

Gestation is averages 53 days (just under two months), with the peak time for births being mid-March.   A study in 1993 on urban foxes found that the gestation period and time of weaning were constant over different populations, but the timing of mating and birth may vary geographically.      When born, the cubs have grey woolly fur, a pink nose (which turns black within the first week), weigh between 50 and 150 grams and are blind for the first 10 to 14 days.   Newborn cubs are unable to thermoregulate fully for the first two or three weeks and must huddle together and, in the early stages, stay close to the vixen to prevent hypothermia.  Indeed, during the first two or three days, the vixen will not leave the cubs, probably because they need her as a 'thermal blanket' until their fur has grown sufficiently to provide some insulation - observations from captive foxes suggest that by the seventh day the cubs generate sufficient heat to be left alone for longer periods.   For several weeks after the birth of the cubs, the vixen's maternal duties involve playing and napping with the cubs, grooming them (paying special attention to the groin and ears) and eating their waste products.

Fox cubs are lactophagus (feed entirely on their mother’s milk) for the first four to five weeks of their life, after which they will have developed a full set of deciduous (milk) teeth and can take solid food (initially that regurgitated by the vixen) - the vixen may start presenting the cubs with solid food from about three weeks old, even though they are only able to suck the juices and play with it (helping to develop jaw muscles and hunting technique).   The dog fox will hunt exclusively for food to sustain the vixen and her cubs; when the cubs are no longer vulnerable (after about six weeks), the vixen will hunt for herself and the cubs.   The cubs are fully weaned by six or eight weeks old (about May time) and, at this point, food is provided by both parents (and often any 'helpers').   As the date of weaning approaches, captive individuals have been observed burying food for their cubs to find.   The cubs emerge from the natal earth at about five weeks old and may be seen playing outside in late April or early May.   In urban settings, adults will bring a range of toys (balls, dog chews, shoes etc.) back to the earth for the cubs to play with.   When the cubs reach three to five months old, they are capable of providing food for themselves and are considered independent of their parents.   Cubs will begin to forage on their own during August, and will be full grown by the end of September; they will reach sexual maturity at nine or ten months old.

On average, only two cubs per litter will survive their first winter and mortality may be as high as 80% in the first year in some locations; having survived the first year, mortality drops to about 50% in each adult year.   Targeted fox hunts kill an estimated 21,500 to 25,000 foxes (roughly 4% of the UK's fox population) annually, while more than 100,000 may be killed on the UK's roads each year.   (Back to Menu)

Behaviour and Social Structure: Although often seen solitarily, foxes tend to live in social (usually family) groups composed of a male, breeding vixen and their cubs.   The family group may also contain subordinates who will usually be 'hangers on' from previous litters or, occasionally, older animals that used to be dominant; subordinates often help raise any subsequent litters by bringing food and baby-sitting.   In the urban fox populations of Bristol, subordinate males are as common as females.   Whether or not a group contains subordinates seems to depend on two key factors: food availability and level of persecution.   Where food availability is high (such as in many urban and suburban environments) large groups with several subordinates can be sustained.   However, under conditions of high persecution, large groups cannot become established.  

Where groups of foxes persist, the social structure among individuals can be strict, with alpha (top) and omega (lower) foxes.   Interestingly, it is the females that take part in, often violent, fights for dominance; males tend to merely leave and look for a new territory.   The population hierarchy is evident in foxes as young as one week old; cubs fight with each other for access to food and establish a feeding hierarchy.   From about 25 days old, there is a fairly distinct 'pecking order' in place, whereby the largest cub -- irrespective of sex -- is usually the alpha.   As the cubs emerge from the earth and begin to forage for food in the immediate periphery (at about six or seven weeks old) the group structure is more obvious.   If a young omega vixen manages to obtain food from a parent (or catches it herself) she will have to either run and hide whilst she eats it, or fight off her siblings.   (Photo: From an early age, fox cubs begin establishing dominance, which will define their place within the family group - often directly affecting the proportion of food they receive.  The aptly-named "fox trot" is one of the ways social dominance is confirmed without bloodshed.)

Not only do alpha vixens hold the rights to first pickings on any food brought in by the male, they also hold the primary mating rights.   With few exceptions (i.e. in some urban fox populations or if food is especially abundant), it is only the alpha vixen that is permitted to mate with the dog fox.  When a new dog fox enters a territory, the omega vixens may ‘flirt’ with him, although his primary interest is often the alpha female.

Foxes communicate with a variety of scent, vocal and visual cues.   Changes in body language or facial expression that may appear subtle to us convey a wealth of information to other foxes about the individual's mood and can be used to settle disputes without the need for direct conflict.   Many of the body postures and facial expressions observed in foxes can be seen in wolves and pet dogs.   I will cover these displays in a separate article (in preparation), but cubs will play bow to each other, while classic dominant (erect ears, tail held high, stiff legged walking) and submissive (low to ground, tail under body, mouth agape) postures are evident in both adults and cubs.   In cases where several foxes are feeding on the same highly localised food source (such as that put out by humans), some are clearly dominant over others.   I have observed a larger fox to turn on a smaller one, crouching low with its tail curled underneath it and ears held flat, while making a rasping 'hacking' or 'hissing noise (it sounds to me that they're blowing air from the back of their throat); in all cases the smaller fox backed away and the larger one resumed feeding.

Male foxes will ‘play fight’ with their siblings, but they don’t appear to engage in any form of social hierarchical interaction.   Indeed, males tend to leave the earth at about the same time as the females begin this infighting (during late autumn when the fox cubs are left to fend for themselves).   As autumn progresses, family cohesion -- which is normally achieved non-aggressively through regular grooming sessions -- begins to degrade and it is often during this time that cubs will begin to leave in search of new territory.   Indeed, from September onwards, the male cubs begin to sexually mature, increasing competition with their father, who will often become increasingly intolerant them.   Some adults may be ousted by their offspring or the entire family may up-sticks and move for no obvious reason.

Cubs disperse from October to January at between six and 12 months old and dispersal distance is inversely related to population density; in other word, the lower the population density, the further animals tend to move.   The distance travelled can vary from a few metres to more than 250 km (recorded in Sweden) and possibly up to 400 km (a female was tracked for 394km in the USA), but it is commonly five to ten home range diameters.   Urban fox cubs disperse less than rural ones and times vary; dispersal in rural foxes begins in the autumn, while urban foxes start dispersing around Christmas time.   According to a report published by the Rural Development Service (part of the Department of Environment Food & Rural Affairs – DEFRA UK – Technical Advisory Note WM08, 2002), urban fox cubs disperse between 3km and 8km (2 - 5 miles) and rarely move into rural areas.   Females may choose not to disperse, opting to remain with their mother and sisters (frequently helping to raise subsequent broods – see Q&A).   However, if a young dog fox should enter the territory, a vixen may join him and leave to establish a territory.   Female foxes that do disperse generally move shorter distances than males.   In the UK, dispersal distances are typically between 5km and 40km, although some movements of 50km have been recorded.   This distance has been shown to vary locally and sexually; one study in rural Wales found that males moved, on average, 14km (8.6 mi), while females travelled only 6.5km (4 mi), while a study of Bristol's foxes reported values of 2.3km (1.4 mi) for males and 800m (0.5 mi) for females.  

In a paper to the journal Animal Behaviour during 1998 Phil Baker and three colleagues at Bristol University found that more offspring -- of either sex -- remained on their natal territory than dispersed, although philopatric offspring (those that didn't disperse) only became dominant when their parent's territory was divided.   Indeed, of the 37 animals Dr Baker and his colleagues monitored, only 9 (24%) dispersed while 28 (76%) stayed on their home territory.   Males were also found to have a greater dispersal success than females: 17 to 67% and 0 to 67% respectively.   Dr Baker and his co-workers also suggested that delayed dispersal -- where animals disperse in their second year -- may promote direct fitness.   In other words, leaving home in your second year may make the dispersal more successful because of your increased experience, keener food-finding skills and better physical condition.   Experience of helping parents raise subsequent broods gained during the first year are likely to prove and aid to the disperser, should they have their own cubs and this may influence philopatry.   If we consider that the reproduction of subordinate females is typically suppressed by the dominant vixen, it seems logical that the principal benefit of dispersal is a longer 'sex life' - those foxes that are successful in their dispersal will tend to obtain dominant status sooner than their philopatric siblings.   Nonetheless, there is a cost that dispersing individuals must face; dispersing foxes have a greater chance of being killed or seriously injured while locating (potentially fighting over) a suitable territory.  

Grooming is an important aspect of fox society and seems to help strengthen interfamily bonds.   A study by Bristol University biologists revealed that male cubs were most affected by the level of social interaction they received during the first 13 weeks of life.   Cubs that received little or no grooming from their littermates were more likely to disperse.   The same was not true of females; the biologists speculated that this may arise because the social factors acting on females generally occur later in life than they do in males.   It seems that females also tended to receive more grooming than males, and were more closely bonded to the social group.

According to an article in the February 2004 issue of BBC Wildlife Magazine by Prof. Harris, foxes make more than 20 different call types (the paper to which Prof. Harris is referring documents 28 different calls) and call throughout the year, although they are most vocal in the winter.   However, it does appear that foxes are pretty quiet outside of the breeding season; in more than 400 hours of tracking, the Bristol foxes made only 77 calls, each lasting only a few seconds.   Sound appears to play an important role in fox society and can help keep track of where your family members are as well as help track down a mate.   New born cubs produce a "whelping" noise, which develops into a more rhythmic "yelping" noise by about three weeks old; the whelping and yelping noises are used by the cub when it needs attention or if it becomes isolated.

It is not only the frequency of calling that increases during the winter (breeding season), but also the number of meetings.   One tracking study in Bristol found that two foxes met, on average, 1.5 to 2 times per night for most of the year, increasing to 2.5 to 3 times in winter.   Additionally, subsequent studies of Bristol's urban foxes has revealed that dominant and subordinate individuals interact with each other more frequently than dominant individuals interact with one another; subordinate individuals also interact with other subordinates more frequently than dominant-dominant dyads.   (Back to Menu)

Interaction with Humans: Foxes began living in our cities after World War I; a response (many people consider) to a change in people’s lifestyles.   Stephen Harris and Phil Baker at Bristol University consider that the most likely "cause" of urban foxes was the development of once rural land after the First World War; land was built upon and, rather than moving, the foxes adapted to their new surroundings.   It even seems that urban foxes are very choosey about where they live, seemingly shunning rented properties and heavy industrialized areas in favour of middle-class residential areas, with a particular penchant for suburbs with owner-occupied housing.   Although foxes probably began to be noticed in our towns and cities after World War I, it wasn't until after World War II that they became commonplace.  (Photo: Garden ponds -- & swimming pools -- represent a welcome source of water for wildlife, although such ornaments are not without their dangers.  Fox cubs have been know to drown in them.)

It is often cited that the outbreak of myxomatosis -- a highly infectious and usually fatal viral disease of rabbits -- in Autumn of 1953 that killed a staggering 99% of Britain's Rabbits (Oryctolagus cuniculus) was the cause of the 'city fox phenomena', because foxes moved into towns and cities looking for food.    Intriguingly, I have heard similar theories bounded around to explain any yearly increases in shark attacks (i.e. over-fishing has led to sharks moving closer into shore looking for food).   However, foxes were apparently quite common in many urban areas by this time: DEFRA (at the time known as MAFF) shot 181 foxes in southeast London during 1947!   Indeed, the data we have on the response of foxes to myxomatosis was quite different.   Rather than moving away looking for more food, foxes were observed "prey switching".   The foxes switched from eating rabbits to field voles (Microtus agrestis).   Moreover, there were actually more cubs produced in the years immediately proceeding the myxomatosis outbreak; probably a result of a super-abundance of easy-to-nab dead or dying rabbits.  

It had long been considered that urban areas were sub-optimal habitats for foxes, acting as a refuge for 'country' foxes that were unable to find suitable rural territory.   However, genetic work on the foxes that have colonized urban areas of Zurich (by a team of scientists from the Zoological Society of London and University of Zurich) has provided some interesting insights on this.   The paper, published in the journal Molecular Ecology during 2003, found no evidence to support this so-called Population Pressure Hypothesis.   Instead, they found significant genetic differentiation between rural and urban foxes, which suggests that the foxes have been breeding more with other urban foxes than with rural ones; had this been poor habitat for foxes, the only thing supporting the population (i.e. replacing those that have died) should be immigration from the surrounding countryside.   Moreover, they observed substantial genetic differentiation between foxes in the eastern and western parts of the city, suggesting two independent colonisations by a small number of rural individuals.   Nonetheless, tracking studies by various teams have shown that urban and rural foxes can and do mix; some individuals living in rural landscapes were tracked entering the city to hunt.   Indeed, the authors of the Swiss study write:

"Currently observed levels of migration between urban and rural populations will probably erode genetic differentiation over time."

Red foxes represent perhaps the most abundant wild canid on Earth, with spring populations in Europe (excluding Russia) estimated at between 750,000 and one million individuals   Current estimations of the number of foxes in the UK stand at 240,000; 195,000 in England, 23,000 in Scotland and 22,000 in Wales (there are no data for Northern Ireland).   It has been suggested that the number of foxes living in urban areas of the UK is probably in the region of 33,000, with 3,000 of those living in Scottish towna and cities.   More surprising is that the number of urban foxes in Britain appears to remain stable despite an annual mortality of 60% (indicating a very short generation time) - although game bag records (i.e. the number of foxes killed by gamekeepers) has increased steadily since the 1960s, there is is no evidence that the fox population has also been on the rise.   Indeed, a study on the cub mortality in Bristol found that 15% of four-week-old cubs died and, of 1000 cubs born, 650 survived to sub-adult status and only 390 made it to adulthood.   The main sources of cub mortality included cold, dogs, badgers and vixen death, while some cubs died when they became entangled in netting and washing lines or fell into ponds and swimming pools.

Foxes can become reasonably tame, and one I had the pleasure of seeing a couple of times (in Horsham, West Sussex) was known to wait under the same tree at a specified time every night for the owner of an adjacent house to supply her supper (of dog food).   Apparently, on one occasion when the waiter was engaged for longer than anticipated and failed to meet the 9pm feeding, the fox crossed the road, went into his front garden, put its paws on the window ledge and peered into his lounge!   Similarly, in their book on Urban Foxes, Steve Harris and Phil Baker cite several examples of foxes having become almost complacent of humans.   In one such example, a vixen apparently used to sit and watch as the children of a household who's garden she frequented sat and played with her cubs.   (Photo: Foxes are highly adaptable and can readily turn their tastes to food -- such as coloured nuts -- left out for the birds)

I think it is rather obvious that foxes don't always come away from their interactions with humans better off.  There are the obvious examples of fox hunting, road traffic mortality and shooting that all take their toll on fox populations.   However, fox mortality through human cause may be more subtle than any of the aforementioned.   During the late 1950s and early 1960s, there was a mass mortality of foxes in eastern England caused by foxes eating birds that had fed on seeds dressed with chemicals.   This 'cascade effect' is often referred to as biomagnification and is, rather unfortunately, common in almost every ecosystem these days.   Predators close to the top of the 'food chain' generally accumulate the highest (and consequently most deadly) levels of toxins.   Indeed, even our attempts to help foxes have been known to fall on stony ground.

A series of experiments by Charles Robertson and Steve Harris (both at Bristol University) -- the results of which were published in the journal Animal Welfare during 1995 -- looked at the survival rate of 26 captive-bred foxes released from a wildlife hospital.   The biologists found that immediately after release there was a phase of erratic behaviour, where the foxes travelled widely.   The individuals that survived this "erratic phase" were seen to enter a second phase after about two-and-a-half weeks, during which one small area was used.   The initial period of high activity lead to high mortality in the foxes, with road traffic accidents being the major cause.   In a second study in the same journal, Drs Robertson and Harris report on the tracking of 251 captive-reared foxes over four years.   The authors found that the stress associated with captive-rearing meant that the released foxes weighed less than their wild counterparts and suffered further weight loss in the period immediately following release; this weight loss was in spite of stomach content analysis, which showed that the released foxes rapidly learnt to hunt successfully.   These studies deal with the fate of captive-reared foxes, but there is similar data to indicate that foxes taken into captivity for treatment or rehabilitation suffer a similar fate.   It seems that when a fox is removed from the wild, a neighbour or nomadic individual will quickly take up its territory.   Consequently, should the fox be returned to the wild (even if it is released in precisely the point at which it was captured) it will find that it no longer has a territory!

Another major area of fox-human interaction is the feeding of wildlife.   I have frequently heard it said that feeding foxes is a bad idea, usually based on two lines of reasoning: 1. Foxes will become dependant upon the food source and starve if said food is removed; 2. Foxes fed by humans are likely to readily lose any fear they have of people (NEVER a good thing for a wild animal!).   While personal observation and anecdotal evidence seems to support the latter notion, given the terrific adaptability of Red foxes, it seems unlikely that they would become dependant on any single food source.   Ecologically, monophagy or stenophagy -- i.e. those that only eat one (or a very narrow range of) thing(s) -- is generally considered a recipe for extinction - after all, if you only feed on a single species and that species dies out, so do you.   By contrast, if you are able to switch your tastes to cover a wide range of food items (i.e. are polyphagous), if one item declines in availability you can more-than-likely switch to another (assuming they don't all decline in concert).   The subject of feeding wildlife (and its associated pros and cons are discussed in a separate Q/A).   Overall, I would conjecture that if you want to feed foxes in your garden, there are a few simple guidelines you should take into consideration:

1. REMEMBER that not everyone is as appreciative of foxes (or of wildlife in general) as you may be.   Neighbours with small livestock that are housed outside (e.g. chickens, rabbits, guinea pigs etc.) may be especially unimpressed by your fox-feeding activities.   It is worth bearing in mind that food foxes take from your feeding station may be buried in your neighbour's garden!
2. DO NOT feed highly processed foods (crisps & snacks), or dry just pet food, and especially NOT chocolate (see Q/A section below for a discussion of this).
3. DO feed them foodstuffs that they are more likely to encounter while foraging naturally (i.e. raw or cooked meats, fruit and berries, vegetables, eggs, earthworms etc.); feeding of canned dog food is also an option.
4. DO put out water - this is more important to the fox (and many other garden mammals) than the food itself.

Putting out food for foxes can lead to changes in territory size -- even the halving of territory size in some urban areas -- and numbers.   In northwest Bristol, Stephen Harris and his colleagues observed a positive feedback loop with regards to householders putting out food for foxes and the number of fox sightings.   The biologists found that as the number of people putting out food for foxes increased, more fox sightings were reported and more food was put out, leading to each given patch being able to support more and more foxes.   At one stage (before mange arrived), Harris and his co-workers recorded 30 adult foxes per square kilometre - the highest density of foxes ever recorded!

Contrary to popular misconception, foxes aren’t (and never have been) classed as vermin and, as such, Councils are not obliged to exercise any form of control over them.   Many people consider foxes to be a nuisance because they may call (sometimes at an ear-piercing pitch) late at night, set off security lights, dig up lawns and flowerbeds, raid bins, kill domestic livestock (especially chickens, ducks, guinea pigs and rabbits), attack pets (see Q&A) and steal fruit and vegetables from their gardens.   Furthermore, they often leave pungent smelling urine and excrement in gardens and occasionally excavate the corpses of buried pets.   Fox cubs are also well known to trash gardens during their play sessions, carrying off pot plants, chewing pots, chewing polyethylene play tunnels and plant protection tunnels as well as becoming entangled in garden netting.   What's more, adult foxes can squeeze through gaps of only 10 square cm (4 in²) and easily scale a 2m (6ft fence), making it difficult to totally exclude them from your garden!   (Photo: As nocturnal predators, having a tapetum behind the retina allows for enhanced low-light vision.   It is light reflecting off the tapetum that causes 'eye-shine')

With regards to the danger posed to pets, people are often concerned that their cat would come off worse in an encounter with a fox.   I think it is important to face up to the fact that foxes do sometimes kill cats, just like they sometimes kill livestock - foxes are predators and that's all there is to it.   However, the fact that these things happen doesn't mean that they're commonplace.   As anyone who's ever tried to give their pet moggy an anti-worm pill can testify, cats have an impressive barrage of sharp claws and equally sharp teeth that they're not afraid to use!   Adult cats are also very agile and foxes seem to know, and even respect this.   People with experience of both foxes and cats generally testify that they give each other a wide berth, and are even indifferent to one another.   However, foxes do occasionally attack and kill cats and study looking into this, led by Stephen Harris, questioned more than 5,000 householders in northwest Bristol about the number of pet cats that were killed by foxes each year.   The survey revealed that each adult fox killed about 0.17 cats each year or, to put it another way, any given fox would kill one cat every six years; most of these were cats less than six months old.   The situation may also be reversed; there are cases where fox cubs have been killed by domestic cats!   (Photo: Contrary to popular misconception, foxes and cats aren't necessarily mortal enemies!   This kitten was apparently living with a group of foxes in Surrey during December 2005 before it was caught and re-homed.)

Despite some valid complaints, neighbourhood foxes do have their benefits.  Even to the exclusion of the joy many people get from interacting with them, foxes are an effective (and free!) method of vermin control (keeping mice and rat populations down) as providing a litter clean-up service by eating discarded food.  

It should be noted that foxes can carry an array of parasites, including hedgehog and dog ticks as well as various tapeworms and roundworms.   In a paper published in the journal Parasitology Research during 2003, Valdmir Shimalov and a colleague at Brest State University in Byelarus (Western Soviet Union) report their analysis of 94 carcasses and 1,213 faecal samples from Red foxes collected from Southern Belarus between 1981 and 2001.  The scientists found a total of 32 helminth (intestinal worm) species – including Alaria, Pearsonema, Taenia, Toxocara, Trichinella larvae and Ucinaria – all of which are considered significant for medical and veterinary health.   A similar study by a team of ten biologists from the UK and Germany carried out a study of 588 foxes across Great Britain to look at disease-causing parasites.   The results, which were published in Veterinary Parasitology in 2003, showed that the most common gut parasites of British foxes were Uncinaria stenocephala (a hookworm) and Toxocara canis (a type of large roundworm well known to infect cats), occurring in 41% and 62% of the foxes, respectively.

Perhaps the most serious Red fox parasite is the Sarcoptes scabei var. vulpes (see image below); the mite that causes sarcoptic mange in foxes (this subject is discussed at greater length in a Q/A).   Some fox parasites can be transmitted to humans: Toxocara canis (leading to Human toxocariasis) and mange (leading to scabies) are a couple of examples.

Of course, disease transmission is often bidirectional -- it can be transferred both ways -- and foxes can catch diseases from domestic animals (e.g. distemper and parvovirus) and rats (e.g. Weil's disease) as well as being vectors for mange (left) -- which may be transmitted to domestic dogs and, very occasionally, cats -- and rabies.   With respect to rabies, there are two possible extremes: 'dumb' (where the virus infects the spinal cord, causing the fox to remain in the den) and 'furious' rabies (which, as the name suggests, causes them to lose all sense of direction and fear, wander considerable distances and attack other animals).   The 'dumb' extreme is more of a problem for the group than the 'furious' extreme, because the infected animal remains in the earth where it is more likely to come into contact with other members of its social group.   There has been a considerable amount of research directed towards finding the best way to eradicate this disease and the use of oral vaccination -- administered via vaccine-injected bait -- is seen as the most effective method.

In Europe (e.g. Turkey, Latvia, Estonia etc.) at least, the incidence of fox rabies shows a distinct seasonal trend, with a peak in March followed by a rapid decline to a low point in June, after which the incidence of rabies begins to rise again.   Given that there will be a short time from consumption of any "treated" bait to the establishment of a sufficient immune response against the rabies virus, it is considered that the best time to deploy these baits is late autumn (during November) or early winter (December).   There are several reasons for this timing.   Deploying the bait during the winter -- when food is generally scarce -- increases the likelihood that it will be consumed and, at the same time, provides three or four months over which the fox can develop an adequate immune response by the time the peak in rabies (and thus the highest likelihood that an uninfected fox will meet an infected animal) arrives.   Finally, some authors have suggested that the energetic costs associated with pregnancy and maternal care, coupled with the suppression of the immune system associated with pregnancy and lactation may make vixens more susceptible to infectious diseases such as rabies.

I think it's safe to say that foxes have experienced a tumultuous relationship with humans.   In their 2004 review of Vulpes vulpes, David Macdonald and John Reynolds note that this species has been hunted as food and fur since at least the 4th Century B.C., while the pastime of hunting foxes for sport with dogs was well established in European culture by the 11th Century, subsequently being spread globally by British colonists.   Similarly, foxes have been seen as an agricultural pest by many farmer and local livestock owners alike.   Whether you love them or hate them, there's no getting away from the fact that foxes are remarkably proficient at eking out a living in our modern world and are deeply entwined in our history and culture.   Perhaps more importantly, at least for those involved, is that despite all the hyperbole, foxes (especially those in towns and cities) have provided thousands of people with a blissful connection to the natural world that is often very difficult to come by.   (Back to Menu)

Related Q/A:

Q: Why help your parents raise your brothers and sisters?
Q: Why shouldn't I feed animals chocolate?
Q. How can I protect my pets from attack by foxes?
Q: Why extend your territory during winter?
Q: Why does my pet dog seem to have a penchant for rolling in fox dung?
Q: What are mange and rabies?
Q: Do foxes kill for "fun" and is surplus killing a waste?
Q: Are foxes colour-blind?
Q: Is there an exception to the 'Fox Scatter Cache' rule and, if so, what are the benefits of scatter caching?
Q: Is it okay for me to feed wildlife? Am I causing any harm by putting out table scraps or seed for local animals?
Q: How significant are foxes and badgers as predators of hedgehogs?
Q: I've rescued an injured fox and want to keep it as a pet.  Is that legal?
 

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