Mammals
Probably the greatest mammal spectacle to be seen this month is the deer breeding season, or rut. October is the peak month for the rutting of red, fallow and sika deer here in the UK. Red deer tend to hold traditional rutting grounds, areas of good grazing that the females are attracted to; the stags are drawn to the females, who form small matriarchal groups, and work hard to keep competing males away for long enough to mate with as many of their harem as possible. The stags roar (or “bolve”) for several reasons: to scare off potential rivals, to attract nearby females, and to help bring the females into oestrus. Research by scientists on the Isle of Rum has revealed that females can tell the size and fitness (and probably the individual deer) from the volume and duration of the roar; larger animals have deeper roars. Much the same applies to fallow and sika, except that the males tend to occupy a good spot (called a lek) where they stand and belch (fallow) or whistle (sika) to attract females.
A Red deer (Cervus elaphus) stag roaring (bolving) during the rut in the UK. - Credit: Marc Baldwin
A Fallow deer (Dama dama) buck groaning (belching) during the rut in the UK - Credit: Marc Baldwin
A Sika deer (Cervus nippon) stag whistling during the rut in the UK - Credit: Marc Baldwin
The deer rut is fascinating and very entertaining to watch, but please remember that, even in deer parks like Richmond, Bushy and Petworth, getting too close can both disturb the deer and be dangerous for you – these are large mammals pumped up on testosterone, and this makes them unpredictable. Please keep your distance and don’t risk your safety, or theirs, for the sake of a photo. If you want to watch the rut this autumn, there are several parks and gardens that hold managed populations of free-ranging deer across the UK – check out the British Deer Society’s website to find one local to you.
October is a good time to check up on your local hedgehogs, which will be out and about during these lengthening nights looking to put on plenty of fat to see them through their winter hibernation. This is the time of year when hedgehogs benefit most from food and water left out in gardens at night. If you’re interested in helping your local hogs, want to make your garden hedgehog friendly, or just know what types of food to put out, check my Helping Hedgehogs this Autumn article.
Squirrels are very active this month, busy caching surplus nuts and seeds for retrieval when pickings are slim. If you head out to your local park or woodland for some squirrel watching, keep an eye on their caching behaviour – you might notice them make phony caches when they think they’re being watched.
Another important event in the mammalian calendar this month is the appearance of seal pups, which are born on beaches during the autumn. As with deer, please be aware that these animals are sensitive to human presence and easily disturbed, so keep your distance. Check out Countryfile’s Britain’s best seal watching spots if you fancy trying your luck.
Red fox family life is now starting to break down and, in some populations, the cubs are starting to disperse as tensions rise and fights become more common. In some groups, cubs may stay around until December and, particularly in urban areas where food is in greater abundance, vixens may remain on their parents’ territory for another year or more. Whether the cubs are about to fly the coop or not, foxes are becoming increasingly territorial as the breeding season approaches and calling tends to increase as a result.
Finally, it’s this time of year that people start to notice lots of dead shrews in the British countryside and wonder if an epidemic has hit the population. In short, no, it’s part of the natural shrew population cycle. Shrews are not long-lived mammals; their size makes them a target for many predators, while their metabolism makes them prone to starvation. A fortunate common shrew could expect to live for 15-18 months in the wild, although around half die before they reach two months old. Indeed, the oldest captive common shrew I’m aware of lived to be just three years old and only 20-30% survive to breed in their first spring.
The shrew breeding season runs from around mid-April until mid-August, so at this time of year we’ve reached the end of the frenetic mating season and this has taken a huge toll on an animal that is already living only on an energetic knife edge, able to survive without food for no more than eight hours. Consequently, many shrews simply die from exhaustion, while others starve to death if they have devoted so much time searching for females or having failed to secure a home range. Indeed, as early as 1935 it was demonstrated that almost all adult common shrews die off during the late summer and early autumn after breeding, and that the overwintering populations is, therefore, almost entirely made up of young born that year. Some shrews are also caught by predators that subsequently discard them thanks to their potent scent gland that releases a distasteful secretion.
So, some of the dead shrews you find will just have died of exhaustion or starvation, while others will have been discarded or accidentally dropped by predators. (It is worth pointing out that it is not always easy to see wounds on shrews and a close inspection in the hand is often required.) There are, however, some more interesting suggestions for this rash of sudden deaths. In his 1950 book, Wild Animals in Britain, Oliver Pike finds the aforementioned ideas an unlikely explanation for the ubiquitous bodies to be found at this time of year, writing:
“I believe that a sudden clap of thunder can kill certain creatures. I have seen a coal tit fall dead from a tree directly after a gun was fired underneath, but pointing in the opposite direction to the bird. Many of these small animals are far more sensitive to sounds than we humans, so it is quite possible that a sudden loud noise close at hand would have a fatal effect.”
As intriguing as Pike’s theory is, it seems unlikely that stochastic events such as thunderstorms (although more common in late summer and autumn) could account for the consistent appearance of dead shrews during these few weeks. I’m of the opinion that the evidence points firmly to the exhaustion/starvation hypothesis, but perhaps thunder takes its toll as well.
Birds
I always think of October as the month of the owl. Little owl chicks have fledged and can be heard calling on mild October nights, while barn owls can often be seen hunting during the day. Moreover, October is the month for “chatty” tawny owls, with a lot of “kee-wick-ing” and “hoo-hoo-ing” going on in our parks and woodlands. These noises, that Shakespeare described as “Tu-whit. Tu-who” in his poem Winter, are contact calls made by tawny owls, and calling increases in frequency as the owls evict their youngsters and become more territorial. Much has been said about sexing owls based on their calls, with the female making the “kee-wick” and the male responding with the “hoo-hoo”, but in reality it’s not that straightforward – I have personally observed a tawny change from kee-wick-ing to hoo-hoo-ing. That said, females do seem vastly more prone to making the kee-wick call than males (I’m reliably informed that males can make it, but generally don’t) and their version of the hoo-hoo is more warbly/tinny in quality than that of the male, which has a deep, resonating quality. Check out my Wildlife Watching - December blog for audio clips. Being territorial now means that not only can they be duped into responding (even approaching) imitated calls thus offering a better view, they are also more prone to calling during the daytime, which catches some people off-guard.
October is also the month during which many of our winter migrants begin arriving, including wigeon from Russia and Scandinavia, woodcock, also from Scandinavia, white-fronted geese from Greenland’s Arctic tundra, pink-footed geese that breed in Iceland and Greenland but winter almost exclusively along our eastern coast, and whooper swans from Iceland. Indeed, whooper swans undertake the longest non-stop flight of any swan in the world, flying from the southern coast of Iceland to southern Scotland. The UK also receives some pochards from continental Europe during the autumn and winter and, interestingly, these are mostly females. Nobody’s really sure why females move further south and west than males, but it’s hypothesised that as males leave earlier they can monopolise the closer sites, forcing females to keep moving in search of winter feeding grounds. Sightings of bearded tits, crossbills, bramblings and redwings, the latter mostly from Fennoscandia, Iceland and the Faroes, also start to increase in southern counties this month.
When birds migrate to Britain for the winter they can be very faithful to particular sites. We know, for example, that specific woodcock return to the New Forest from Europe each winter and ringing studies by the RSPB and BTO have shown some waders, such as black-tailed godwits, show a distinct preference for only a handful of their reserves. It’s also not just the waders and ducks that arrive in Britain this time of year and, as garden writer Kate Bradbury put it in the Spring 2019 issue of the RSPB’s Nature’s Home magazine:
“Few UK garden bird watchers are aware of the sheer extent of the incoming autumn migration to these shores.”
Indeed, an enormous number of blackbirds migrate to Britain for winter, while there’s a mixing of song thrushes; large numbers coming in from the continent and some British birds heading south to France and Iberia. Similarly, some goldfinches and siskins come over from Europe, while some that have bred in the UK move south. We’re also starting to see some blackcaps overwintering in Britain. Historically, birds from the Low Countries and Germany have migrated to France or Spain to overwinter, but we think climate change is resulting in some coming here to spend the winter instead.
Reptiles & amphibians
Warm, sunny days during October will tempt out some reptiles, particularly juveniles born earlier in the year. Most reptiles will, however, begin preparing for hibernation towards the end of this month, so encounters will become less common. The same is true for amphibians, although there are still plenty of froglets and toadlets around at the moment. It's also not uncommon to come across a few adult frogs in the long grass of lawns at this time of year, so please be careful if giving your lawn a final cut before winter.
Fish
Salmon and sea trout take advantage of the higher water levels this month to make their return to their spawning grounds. October is, therefore, a great month to watch these energetic fish jumping weirs and waterfalls.
Invertebrates
There are fewer butterflies and dragonflies around in October. A few to keep an eye out for this month include small tortoiseshell butterflies, the ivy-loving herald moth, the striking yellow and orange vestal moth, the appropriately-named large white and clouded yellow butterflies and the occasional southern hawker dragonfly.
Perhaps the most obvious invertebrates around now are the eight-legged ones: the spiders. Orb weaver (Araneus) spiders are everywhere at the moment, their webs covering grass and gorse bush alike. Most of these spiders are “garden spiders” (Araneus diadematus), which come in a deceptively broad range of colours, but there are other orb weavers in attendance, as well as the odd late wasp spider. Check out the edges of pools, particularly on heathland, this month for one of Britain’s largest arachnids, the raft spider. These large spiders are chocolate brown with white stripes and are widespread on heathlands in southern England, but only sparsely distributed across the rest of the UK.
Those of you with serious arachnophobia might dread the autumn, because this is when spiders tend to be found more frequently in our houses. A survey by the charity BugLife published in 2009 suggested that every domestic property (i.e. house and garden) in Britain has, on average, 30 spiders; this adds up to some 750 million arachnids. Why do spiders suddenly appear inside in autumn? Well, September and October is the breeding season for most of our common spider species, so, in most cases, those we find in our houses at this time of year are male “house spiders” (the common name given to several species of the Tegenaria and Eratigena genera) looking for females. The females live in lofts, behind skirting boards, in window frames, etc. all year round, and the wandering males come inside looking for them during the autumn. It is currently thought that the males follow scent trails when looking for females and will often use the same routes each day in their search; this explains why, if you don’t squash them, you often find a spider in about the same spot each night.
Now is a good time to search for galls, small deformities in buds and leaves caused by the activities of tiny insects called gall wasps. The wasps lay their eggs in the leaves or twigs of plants – mainly oak in the UK, but also sometimes other species such as roses – and as the grub grows it distorts the tissue, causing an often elaborate callous (known as a gall) to form. We don’t know exactly what causes gall formation - whether it’s a physical, chemical or viral reaction - but we do know that it provides a safe haven for the developing grub during its most vulnerable life stage, and that the grub itself feeds on the tissue inside the gall. When the grub is fully grown it pupates in the gall and the wasp then eats its way out, leaving a neat hole in the middle. More information on the common types of gall found in the UK is on the Royal Horticultural Society’s website. Other wasp species can be found feasting on rotting fruit this month, while recently-hatched honey bees will be starting to feed on the honey produced by the hive over the spring and summer – they will burn off these calories vibrating their flight muscle en masse to keep the colony warm through the winter.
A walk on the beach can be bracing this time of year, particularly as storms start sweeping in from the Atlantic. If you are on the coast this month, keep an eye out for flotsam washed ashore, particularly clumps of whelk eggs, cuttlefish bones, bladderwrack seaweed, jellyfish (even Portuguese man-o-war around Land’s End in Cornwall) and clumps of odd-looking goose barnacles, which look a bit like colourful mussel shells on long, brown gelatinous stalks.
Plants & fungi
Arguably, the feature that makes autumn special is when the deciduous trees start shutting down for the winter. We may not have the large maple forests of North America that put on a truly spectacular show during autumn, but our oak, beech and birch woods come a close second.
As winter approaches, the hours and strength of sunlight decrease and the trees aren’t able to photosynthesise efficiently, making their leaves a liability both in terms of water loss and structural resistance in the strong winds that often accompany autumn and winter. (The “big storm” of 1987 was so devastating to many of our woodlands because it came unseasonably early, when most of the trees still had their leaves.) So, the trees cut their losses. They stop photosynthesis, and a layer of special cork cells called an abscission zone forms at the base of the leaves. The abscission zone cuts off the food and oxygen supply to the leaf, causing it to die.
Eventually the cork layer breaks and the leaf falls to the ground. Before this, though, a couple of things happen. The chlorophyll, the green pigment in the leaf that captures sunlight, breaks down to reveal the more stable yellow (xanthophyll) and red/orange (carotenoid) pigments that are always present in the leaf but usually masked by the chlorophyll. The tree also pumps waste products, known as tannins, into the leaf, adding to the brown colour given by the cell walls, before the leaf drops. So, autumn is a kind of “detox” for the tree as well as a shutting down. More than this, though, the fallen leaves are broken down by detritivores, releasing nutrients back into the soil and acting as fertiliser for the tree.
In some of our non-native maples, as well as a few natives such as wild cherry and dogwood, once about half of the chlorophyll in the leaf has degraded, sunny days and cold, crisp nights trigger a reaction between phenols (pesticides produced by the trees) and sugars in the leaf resulting in the production of pigments known as anthocyanins, which give the leaves a rich dark red or purple colour.
In amongst this carpet of colourful leaves you can usually find fungi, which form a crucial part of the recycling process – in fact, were it not for fungi, almost no woody tissue would be recycled in our forests. October is a great month for fungi spotting, and a few to look out for are shaggy inkcap on grassy areas, the striking orange-peel fungus, the dripping beefsteak fungus on oaks and sweet chestnut, the repugnant-smelling stinkhorn fungus, and the familiar red and white spotted fly agaric.
It’s worth remembering with fungi that what you see is the tip of the figurative iceberg – the bulk of the fungus exists as a network of thread-like hyphae (collectively called a mycelia) below ground, often extending many hundreds of metres away from the toadstool. Some productive forests can have 70km (43 miles) of fungal hyphae packed into a gram of soil. When you see a toadstool, remember the hidden mycelia may cover 15ha (37 acres) below your feet, weigh 100 tonnes and be 1,500 years old.
Elsewhere, non-native Fuchsia plants offer welcome nectar to hummingbird hawk moths this month, having become established in our countryside following importation into stately gardens during the 18th century, and the orange berries of the sea buckthorn add a splash of colour to coastal dunes now.