After the winter hiatus, “normal” feeding resumes and even where large clans persist, individuals typically forage solitarily. Tracking studies have demonstrated that clan members will often use the same feeding sites at different times throughout the night and that badgers tend to move from sett to sett within their range, only rarely straying into a neighbouring territory. Interestingly, badgers are more likely to be found feeding alone during the spring, becoming gradually more social as the year progresses. Regular social feeding is common by about May and whole clans may forage together during the autumn.
The feeding regime of the badger may be influenced by prevailing weather conditions and in his book, Badgers, Michael Clark notes that gales make feeding badgers nervous – this is a common observation among mammals and strong winds presumably make detection of potential threats by scent more difficult.
Badgers are variously described as opportunistic omnivores or local specialists. Throughout much of their range (and across the entire UK) they feed primarily on oligochaetes (earthworms). One 1981 study on badgers from six areas in Scotland, for example, concluded that the dominant food at every site was earthworms (Lumbricus terrestris and L. rubellus). Similarly, a study on a population of badgers in southwest Britain found that 75% of individuals had worms in their stomach, with 65% having only worms. Various authors report that it is not uncommon for a single adult badger to eat 200 earthworms per night, especially on warm, still, damp nights, which make for excellent worming. Indeed, throughout much of their range, earthworms comprise about half of the badger's diet, while mammals and insects constitute about 10% and 15%, respectively.
Birds & mammals
Badgers may also take birds and their eggs, although precisely how significant they are as an avian predator is still a matter of debate. Anecdotal evidence, largely from the 1940s and 1950s, suggests that badgers may occasionally be responsible for heavy losses of gamebirds and it appears that in years when their preferred food is scarce, badgers may take more birds. However, there is little in the way of documentary evidence to support these notions. Indeed, from the numerous studies looking at the diet of badgers across their range, it seems that birds are an uncommon addition to their diet.
A study by the Department for Environment, Food and Rural Affairs (DEFRA) found that out of 289 calls regarding “nuisance badgers” in 2001 and 2002, only seven (2.4%) concerned predation on domestic fowl. Moreover, in an extensive review of records of birds in the diet badgers, Tim Hounsome and Richard Delahay of the Central Science Laboratory in York report that bird remains were recorded in 2,038 out of 36,699 stomach content and faecal analyses in the literature, representing 5.5% overall, or roughly 8% when considering only UK records. They also found that, although the percentage frequency of occurrence of birds in the diet increased significantly with latitude, there was no obvious connection between the presence of birds in the diet and season. Hounsome and Delahay, in conjunction with several other authors, suggest that many of the bird remains found could have been scavenged carrion, making it difficult to assess the potential impact of badgers on bird populations.
Badgers will actively predate rabbits (Oryctolagus cuniculus), which are neatly skinned to leave only the stomach and caecum, and are one of two British hedgehog-eaters (the other being the Red Fox); foxes tend to eat the skin of the hedgehog, while badgers leave it (see QA). Apparently, bearing witness to hedgehog predation is not something for the faint-hearted. In his Wildguide, acclaimed wildlife photographer and presenter Simon King wrote:
“Of all the predators in Britain, badgers seem best equipped to deal with hedgehogs as a meal, digging a shallow pit next to the curled pin-cushion, rolling it in with muzzle or fore feet, and then using enormous power and long front claws to prize open the packed lunch. This whole procedure is usually punctuated by very loud and pitiful screams and grunts coming from the terrified hedgehog.”
Changing with the times
Being opportunistic omnivores, the proportion of various food items varies according to location and season. A study by Eloy Revilla and Francisco Palomares published in the Canadian Journal of Zoology in 2002 found that the main food resource for badgers was young rabbits during the winter and spring, fruits in the autumn and reptiles in the summer months. The scientists also report that consumption of rabbits (both juvenile and adults) was related to rabbit abundance, with a “type-3 response”. In other words, as young rabbits increased in number, badgers slowly adjusted their diet to include more of them. Thus, it seems that in their study area of Spain at least, badgers are generalists and are not locally specialized. A similar study by biologists at the Euskal Herriko Unibersitatea in Spain found that the diet of a badger clan from Biscay varied with season; fruit was a staple constituent in summer and earthworms were the main component in all other seasons.
A study of badgers in Denmark found that cereals were an important part of the diet during the spring and autumn, with small mammals more important during the summer months. This study also reported that, during the autumn, males ate twice as many earthworms as did females and that diet composition did not differ significantly with age. This dietic variation has led to considerable debate over ascribing badgers to a feeding type. I think that Carnivore biologist Hans Kruuk, formerly of Aberdeen University in Scotland, summed the situation up quite nicely in his book Hunter and Hunted, in which he wrote:
“More complicated still, the Eurasian badger, for instance, may be highly focused in its food selection in any one area, concentrating on earthworms in northwest Europe, on rabbits in southern Spain and on olives in northern Italy. There is no doubt that in each of these areas badgers are highly specialized compared with the other predators around. Nevertheless, their specializations are different in different places. There is still earnest scientific debate about whether this animal is an omnivore or a specialist (I call it a local specialist).”
If one were wishing a more cautious approach to classifying badger feeding habits, an alternative definition was given by Universidad Rey Juan Carlos' Emilio Virgós and his colleagues in their 2004 contribution to the Canadian Journal of Zoology, in which they describe badgers as:
“facultative specialists that search preferentially for earthworms but probably take other food resources during their foraging bouts (beetles, fruits, and fungi).”
Regardless of the trophic 'category' to which you choose to assign Meles meles, in most populations, badgers feed copiously in the spring and summer months and have laid down appreciable subcutaneous (under the skin) fat reserves by the autumn. This layer of fat can be considerable and may increase the badger’s weight by as much as 60%. Indeed, many consider the abundance of food resources to be ultimately responsible for the great variation in badger sociality (i.e. it is the underlying cause of badgers living either solitarily or as groups); recent work from Poland and Oxford certainly seems to support this idea.
Across their range, badgers will also take insects (including caterpillars and moths), beetles, small mammals (including voles, rats, mice, moles, young rabbits and hedgehogs), fish, frogs, berries, roots, bulbs, nuts, fruit (in the autumn), fungi and plant material, particularly cereals such as oats and wheat. In the UK, badgers seem particularly partial to elder berries, the seeds of which they distribute in their dung. In a similar manner to most other mammals, the scat can often provide vital clues to the diet of the animal, because different foods lead to changes in consistency. Soft scat is associated with earthworms, while more jelly-like excrement implies a predominance of berries and fruits in the diet. In some areas, badgers may dig out and eat the contents of wasp and bee nests, including the larvae, pupae, honey and honeycomb. They will eat carrion and those in urban areas are known to scavenge food from bins and gardens and may occasionally break into poultry houses or take other small domestic animals, but such instances are considered rare.