Sitting out the winter

The cold winter months, with their low temperatures and long nights, can prove challenging for many creatures. Food may be hard to come by and energetic costs high, so many insects, birds and mammals adopt different strategies to see out the winter days and wait for the arrival of spring.

Some birds, including many of our familiar summer songsters, will have migrated south to seek out more favourable conditions. It is those species that feed on insects and other invertebrates that would face the greatest difficulties were they to remain here during the winter and so many move into Africa, perhaps crossing the Equator to take advantage of the bounty that follows the seasonal rains. Some insect-eating species, however, choose to remain here. Wrens, for example, manage to scrape a meagre living by maintaining winter territories, often establishing these in river or lakeside habitats, where the damp conditions favour higher levels of insect activity. Others, such as the Pied Wagtail, seek the warmth of commercial glasshouses or the waste heat of city centres to reduce their energetic costs overnight.

Some of our insects over-winter as adults, perhaps entering torpor, reducing their ‘running costs’ and lowering their energetic demands. A few of our resident butterflies, for example, overwinter as adults, while nine species overwinter as eggs and eleven as pupae; the majority, however, spend the winter as caterpillars. It is also interesting to note that, with the exception of the speckled wood butterfly, the hibernating phase is always the same in a given butterfly species. Only in the speckled wood can hibernation occur as either a caterpillar or as a pupa. Other insects have a life cycle that sees eggs laid in summer or autumn used to secure passage through into spring. Eggs can be deposited in sheltered locations, they are often robust and require no external nutrition.

Mammals tend to cope with the conditions rather well and many species remain active throughout the winter, some even using these months for their mating season. A small number of mammal species enter hibernation, using fat reserves laid down during the bountiful conditions of autumn to get them through the winter. Others reduce the amount of time that they are active or retire to more favourable habitats.

What is particularly interesting about all this is the way in which so many different strategies are adopted. What suits one species does not necessarily suit another and even closely related species may do something completely different. This highlights that there are different evolutionary solutions to a common problem and this is one of the reasons why the study of natural history is so engaging. There is always something new to see and to discover.

This is mine!

The forest echoes with the calls of Tawny Owls in the dark before dawn. These are territorial birds, proclaiming their rights with a vocal display that carries through the otherwise still air. The ‘hoo-hu-huhuhuhooo’ of the male is answered by another more distant. More often than not his mate will also answer with the ‘keewik’ contact call, forming a duet that reinforces the message that this is an occupied territory. Female Tawny Owls may sometimes give a similar territorial hoot to that of the male, though it is higher in pitch, less well phrased and somewhat scratchy in tone.

The chances are that this pair will have bred on this territory earlier in the year, for the Tawny Owl is a sedentary species not prone to wandering. The sedentary habit and maintenance of a year-round territory provide the Tawny Owl with the familiarity needed to move around the territory safely – although good, even Tawny Owl vision cannot see in complete darkness and birds may occasionally collide with unfamiliar trees or branches – and to find sufficient food. Knowledge of the territory supports success and a successful pair will seek to maintain ownership with their vocalisations.

A fair amount of work has been done, looking into the structure of Tawny Owl calls and this has revealed some interesting things. It seems, for example, that the structure of each territorial call is particular to the individual allowing other owls to recognise each bird as an individual. Territory-holding owls use this information to identify neighbouring birds and to discriminate these from strangers who might be more likely to intrude into the territory. Calling is thought to carry a cost, perhaps because it takes up time that could be used for some other activity (such as feeding) or perhaps because it exposes the caller to an increased risk of predation. Because of this, you might predict that calling Tawny Owls would direct their efforts towards strangers and reduce the amount of calling that they direct at known neighbours, which is precisely what they do.

Tawny Owl calls also appear to carry some information about the bird making the call. The pitch and duration of the call appear to reflect the size of the bird calling and it has also been found that the calls of birds carrying high levels of blood parasites – common parasites in owls and other birds – produce less diverse calls than healthy birds. This suggests that the calls might provide an honest signal of the ‘quality’ of the bird making the call, something that could be used by a potential mate to determine the suitability of a potential partner. Whatever being imparted to other owls, to our ears the calls are simple, conjuring up the spirit of the forest at night.

Frost

The brightness of the moon, descending towards dawn, leaves the clear-fell bathed in light. Dead grass stems, thickened with frost, have the appearance of fragile bone, creating an expanse pale colour that contrasts with the dark depths of the silent conifers standing sentinel behind. Each of my two dogs leaves a visible cloud of exhaled air, like two furry steam trains puffing their way along the forest track. It is the end of a beautiful night and a bright clear morning lies ahead.

Overhead a procession of Rooks is heading out from the overnight roost to seek food in the surrounding fields. They are early risers, unlike the Woodpigeons who stumble from sleep and their treetop perches as I approach the shelterbelt that runs alongside this part of the track. A bird rises from the verge ahead of the dogs, a rounded body carried on broad wings – a Woodcock and my first of the winter in the forest. They are not uncommon here at this time of the year, resting by day in the cover of the forest and feeding by night on the soft arable that surrounds. Presumably, they must feed in the shadow of the forest on nights like this when the frost crisps the soil’s surface and makes probing for worms that much more difficult.

A larger shadow can be seen further ahead, slipping quietly across the track before pausing to take stock of me and the dogs. It is the fox whose scent I often smell along this particular stretch, stringent and clawing on the throat. Satisfied it slips into the undergrowth and away. A late Tawny Owl calls, the call itself somewhat shrill and incomplete. Perhaps this is a young bird setting up territory for the first time. The call is sufficient, however, for one of the resident birds to respond with a mature, resonant hoot. Soon other birds respond, a brief overture of noise before silence returns.

It is then that I pick up the flight calls of Redwing passing overhead. These birds may be on the move because of the colder conditions pushing in from further north. Frozen ground can spell disaster for them, restricting access to the soil-dwelling invertebrates on which they depend. These small thrushes seem to exist on a knife-edge at this time of the year, on the move continually to seek out the best feeding conditions and making journeys that may carry them south into continental Europe or west towards Ireland.

In many ways I find this the best time of the year to be out in the forest. There is none of the dry heat of summer or the damp of later autumn. It is crisp, clear and makes you feel alive.

Signs that our Otters are well-established

The loss of a young Otter, hit by a car as it left the relative safety of the river, was the sad news that greeted me as I arrived at work the other day. The Otter had died not far from where two had been seen playing and feeding the previous week and it underlined the threats that these amazing creatures face as they continue to re-establish themselves within our increasingly busy countryside.

The sad news was balanced somewhat by the sight of an Otter, alive and well, further downstream just a few hours later. Walking back to work along the river I had spotted the Otter break the surface near to the old bridge that echoes an ancient crossing point. This particular individual provided me with some of my best ever views of a wild Otter, as it worked the weed, flushing fish and then crunching on their silver forms. At one point the Otter was feeding within just a few feet of me and the small crowd of colleagues who had by now gathered for this impromptu display of aquatic dexterity. The Otter seemed completely unperturbed by the audience it had drawn, continuing to fish and crunch and, just occasionally, to look at us as if to say ‘move along now, nothing to see here.’

Move along we did, once our lunchtime viewing had extended somewhat into the afternoon’s work. Back at the office word soon got around and another party trooped down to the river to take in the spectacle. For them the viewing was even better, the enjoyment increased by the arrival of a second Otter – a wonderful sign of how well the Otters were now doing on this stretch of the river.

The sighting of the Otter had come a week after I had acquired a copy Miriam Darlington’s new book ‘Otter Country’ a beautifully poetic and personal account of her search for wild Otters. Miriam and I had chatted about ‘my’ Otters when she last came to the Brecks and she would have been mesmerised by the performance of these individuals and surprised by their indifference to us human observers. She might also have been surprised by the indifference shown by many of the people who walk, run or cycle alongside the river on a daily basis, unaware of the Otters. On some occasions, where I have pointed out one of the Otters or answered a query as to what it is that I am looking at, they stare blankly as if unable to comprehend the presence of such a creature here, so close to town. I dare not tell them that the Otters can sometimes be seen fishing just outside the local branch of Argos!

New virus hits Great Tits

The arrival of a new strain of avian pox has been in the news of late, thanks to the publication of a piece of research with which I was involved. The sight of any diseased bird can prove distressing but to see one with a huge growth covering part of its face is particularly upsetting. This, unfortunately, is what we have been seeing over the last few years in some of our Great Tits and it seems likely that we will see more individuals suffering from this virus as it spreads further across the country.

Avian pox is a familiar enough sight, with small lesions not uncommonly reported from Blackbirds, House Sparrows and Dunnocks, among others. This strain of pox virus is less severe and birds often recover. That recently found in British Great Tits is far more unpleasant and the large growths can restrict vision and movement, making the birds more prone to predation and to secondary infection.

My work at the BTO, carried out in association with vets at the Institute of Zoology, researchers at the RSPB and at the Edward Grey Institute in Oxford, has revealed that the virus being seen in our Great Tits is the same as that found in certain continental populations in the past. Not only that, but we have been able to trace its spread since the first case was diagnosed in 2006. Using information collected by BTO Garden BirdWatchers, who keep a weekly count of the birds and other wildlife using their gardens, we have been able to document the disease as it has crept northwards across the UK from an origin somewhere near the south coast. The pattern of arrival, coupled with our knowledge of Great Tit movements, underlines that the virus was almost certainly transported here by a biting insect, possibly a mosquito. British Great Tits are largely sedentary in their habits so it is very unlikely to have arrived via an already infected bird.

You may recall the arrival of blue tongue disease in East Anglia and the link to the continent via a plume of warm from the south bringing with it the biting midges that transport the disease. Something very similar may have happened in the case of the avian pox that we are seeing in these unfortunate Great Tits. Transmission between birds is primarily via biting insects but the virus may also be spread by bird-to-bird contact or via contaminated surfaces, so you should maintain suitable hygiene practices around your garden feeding stations. Hanging feeders and bird tables should be washed weekly, using disinfectant before being rinsed and then air-dried. If you see lots of diseased birds then consider ceasing feeding altogether for a few weeks. 

In search of the wild

It is all too easy to think of wild as something remote and unobtainable, to imagine that it exists only on some distant mountain slope, offshore island or in some hidden sunken lane. We sense that our increasing reach and untidy habits leave even the most remote of places touched by our activities, the wild tamed or tainted. While all this is true, it is easy enough to discover wildness much closer to home. Wild is the late November wind that batters the shutters, the rain that runs down the window, the dark shadow of that slips into an urban river and the plants that push up between the cracks in the town centre pavement. Wild is everywhere and however much we try to conquer it, it will always find a way.

It is not so much that the wild has been tamed but more that we have become too comfortable with our modern existence and can no longer see it. Part of the reason for this is that we rarely, if ever, have to face the dangerous wild, the wild that challenges us, scares us and has the potential to harm. No large predators stalk our countryside; we have just the one venomous snake and there are few creatures with enough bite or sting to threaten. No longer do we have to take risks. We are comfortable and secure but sense there is something missing. It is this sense of something being missing that drives some of us to seek out the more remote parts of our archipelago, to promote ‘rewilding’ and daydream of the return of big cats and other missing carnivores.

Of course, we do not have to go as far as reintroducing Lynx or Wolf to rediscover our missing wild. All we need to do is step outside from time to time and engage with the natural world around us. It might appear a bit ‘new age’ to suggest immersing yourself in a late summer hay meadow or to insinuate yourself into the middle of a blackthorn thicket, but to do so will envelop your senses with the buzzings and scratchings and sniffings of wild. Peer at the weedy looking plant emerging from the narrowest of cracks in the pavement and discover the vitality that drives it to conquer our attempt to blanket it out. Seek out the creatures that have gained access to your home, the spiders, silverfish, moths and woodlice, and delight in their persistence.

The wild should never be completely understood, and perhaps it should probably carry a hint of danger, but it needs to become a more central part of our daily lives. It is part of us and we are part of it.

The wandering water-ouzel

On the south-east edge of Thetford stands an aged bridge; it is stone-built, strongly arched and full of character. No longer used by traffic, other than of the pedestrian kind, the bridge is partnered by a more modern construction a few metres to the south over which the main road now runs. It is here that the Otters are sometimes sighted and it was here, just a fortnight ago, that a wandering ‘water ouzel’ put in an appearance. ‘Water ouzel’ is an old name for the Dipper, a bird of the bubbling, fast-moving rivers and streams of the north and west of Britain.

Other than a few local or altitudinal movements to escape the worst of the winter weather, British Dippers are sedentary in their habits and unlikely to stray into the flatlands of Eastern England. This suggests that the individuals which turn up in Norfolk are likely to have arrived from overseas, most likely from Scandinavia. Usefully, most of these longer-distance visitors are ‘Black-bellied Dippers’, distinctive in appearance and belonging to a different race to the one which breeds in the west of Britain.

Reminiscent of a thrush or a rather solid and chunky looking Robin in structure, the Dipper is a dark-coloured bird, deep brown across the upperparts, with a white chest. In size it is similar to a Starling. The belly has tones of warm chestnut in the British race, while in the black-bellied race it is black or dark brown. This is a bird of character, not least for its ability to feed underwater, probing between submerged boulders and pebbles in search of aquatic invertebrates. The compact body shape, coupled with strengthened bones, no doubt aids the bird as it battles against the current and its own buoyancy.

The Dipper has a tendency to make small bobbing movements when perched, like tiny curtseys, something that is reflected in the name. These add to the character and I always feel a flush of excitement when I watch a Dipper. It is a bird that lives on the margins of two different worlds, a bird which swims and dives but which can also take to the air.

Much of the river along this section appears unsuitable for a visiting Dipper, being deeper and slow-flowing, but there are a few places along its length where the water flows over stony shallows providing feeding opportunities. Whether or not the bird will spend the winter here is unclear and it may be that it moves on to seek out more favourable conditions elsewhere. While it has been present it has attracted a good deal of interest from local birdwatchers and even the local dog-walkers have been talking about the bird and the crowd it has drawn.

Soundscape

Writing in the 1920s, soon after the Great War and the loss of her husband, Helen Thomas recalled a trip that they had made together to the Wiltshire downs. From her description of the cottage in which they stayed and the natural world around it, it is clear that this experience of the countryside made a very great impression on Helen. One particular passage resonates with me and provides perhaps the best description of the silence that the countryside delivers. Helen wrote ‘No other sound was to be heard, no trams, no people, no traffic, nothing but the sounds that do not spoil silence, but rather deepen it…’

For me, such words capture the true strength of the countryside and its stillness. It is not a silent world but one in which natural sounds enhance the sense of peace and welcome comfort. Helen’s husband to be, accompanying her on this first trip, was Edward Thomas, a poet, reviewer and writer on nature and the countryside. Edward, like Helen, was a great walker. Prone to bouts of deep melancholy, he would sometimes stride from the house angry and bitter to seek relief through long hours spent alone, pacing through the countryside. Edward Thomas found peace in nature, the welcoming stillness of the countryside allowing him to battle his inner demons.

The countryside has changed a great deal since that time and the sounds of human activity reach even the most remote parts of our small island. Traffic noise insinuates itself throughout much of the day and passenger jets add a deeper background rumble. Neither, however, is as intrusive as the roar of military planes flying low and fast or the sharp retort of sporting guns. Such abrupt sounds penetrate the calm in a manner that cannot be ignored.

It is only during the hours of night that a sense of stillness can truly be felt, as our activities dwindle though never quite ceasing altogether. Then, even in the middle of a town as dusk slips towards dark, the stillness descends, the evening song of robin and blackbird becoming more resonant, deepening the silence. The air feels heavier; you begin to pick out other natural sounds and feel more at one with your surroundings.

As individuals we benefit from the stillness of the natural world and the opportunity to settle within its embrace. It provides space for reflection, increases our sense of place and, importantly, is free from the sounds that would otherwise claw at our attention. We are so busy filtering out the artificial, day-to-day sounds of the world around us, that we lose sight of the natural world and, by doing so, lose the all-important bond that helps to keep us rooted.

A nutty problem

It seems that many of us have noticed that there seem to be more squirrels around this autumn, with individuals turning up at sites, like Lakenheath Fen, where they are rarely seen. According to correspondence and comments made in online forums, the numbers of squirrels using garden feeding stations across the county are also up, with individuals raiding bird feeders and hanging fat balls in a sometimes troublesome manner. Our personal observations are supported by data collected through the BTO’s weekly Garden BirdWatch survey (www.bto.org/gbw), whose systematic records also show a substantial increase in squirrels this year. According to their figures, the use of gardens by squirrels is currently a third up on the same period for previous years.

So what is behind this increase in sightings? Is it a case of the squirrels having had a good breeding season, such that there are simply more of them around, or is a shortage of tree seeds forcing them to travel farther afield, delivering more of them into our gardens and urban parks? It might be a combination of both of these things, the increase having started fairly early in the year but it certainly seems to be the case that seed crops have been poor this autumn, with beech mast in particularly short supply.

The lack of tree seed has been having an impact on other species too. We have seen many more Jays around this autumn, struggling perhaps to find acorns and having to cover more ground. It is even possible that some of these birds will be immigrants from the continent. There have also been some big movements of Woodpigeons (a species that makes good use of the autumn beech mast crop) along the east coast. Additionally, many people are reporting Nuthatch, Coal Tit and Chaffinch appearing in greater numbers in their gardens than is usual for the time of the year.

It is also worth mentioning those birds that feed on berries, since these also seem to be having a hard time this autumn. Included with these, alongside the more familiar thrushes and Starlings, are rare visitors like Waxwing, a species that has already begun to arrive in northern Britain in growing numbers this autumn and which is likely to push south in the weeks ahead. I would expect to see some of these stunning birds feeding on the berry-producing shrubs used as amenity planting in supermarket car parks and new housing estates later in the winter.

These birds and mammals may well be facing challenging times this winter and so any helping hand that you can spare may be particularly worthwhile. In return you might be treated to the sight of a garden full of visitors.

Marine wonders

I could tell that Harriet was hooked on the marine world by the glint in her eye as she described her most recent dive, made on the chalk reef that sits just off the North Norfolk coast. The enthusiasm underlined that this was a new experience, a first glimpse of the diverse community of organisms that lives below the surface of our coastal waters. Harriet Mead is a sculptor, president of the Society of Wildlife Artists and recent recipient of a diving bursary from The Wildlife Trusts. This bursary has been given annually for the last five years to highlight our marine communities and the threats that face them. Harriet was diving the Cromer Shoal Chalk Beds, often referred to as the Cromer chalk Reef, sketching the wildlife she encountered before creating the wonderful sculptures that are now on display at the Mall Galleries in London.

You may well have come across news of this chalk reef through features on local television or in the EDP. The reef’s important contribution to our marine ecosystem has only recently come to light and, quite rightly, it has been recommended for Marine Conservation Zone status. The first of these zones was designated around Lundy in the Bristol Channel in 2010 and others have since been designated or put forward as candidates through the Marine Conservation Zone Project, a partnership bringing together people who use the sea for their livelihood or leisure. The extent of the chalk beds and the range of creatures that they support is being catalogued by local divers who are discovering new things all of the time. The beds could prove to be Europe’s largest chalk reef and they have already revealed species new to science, most notably a new species of purple sponge.

The reef, with its boulders, stacks and arches, provides an array of microhabitats for the many different creatures that live on it. From delicate sea slugs and pipefish to robust crabs and beautiful worms, the reef is rich with life. Harriet’s sculptures deliver a taste of this underwater world; recreated from scrap metal we see the solidity of a lobster, claws raised in defiance, and the curves of a baby cuttlefish – the size of a bumblebee – that squirted ink and then dropped to hide in the sand. Such works provide an insight into this marine community and raise the profile of the important efforts that are being made to secure the reef’s future.  I suspect that Harriet will be diving the reef again and again, delighting in this new experience and the creatures with which she is sharing it. Information on the Cromer Shoal Chalk beds can be found at www.wildlifetrusts.org/MCZ/cromer-shoal-chalk-beds and Harriet’s work can be seen at www.harrietmead.co.uk

Traveller of the fields

The harsh dry calls of passing Fieldfares have become a feature of my early morning walks, the distinctive notes resonant in the half-light. An upward glance and I can just about make out the shapes of these larger thrushes, newly arrived from Scandinavia, as they flick by overhead. I am equally likely to stumble across these birds later in the day, perhaps flushing a flock from a berry-covered hedgerow or a quiet pasture.

Good numbers have arrived this autumn, perhaps a little later than in recent years but I suspect that we will see a sizeable population wintering here. Fieldfares tend to remain on their breeding grounds for as long as there is food available. Rowan berries are favoured and once these are gone the birds move on elsewhere, often in the company of other thrushes. The movements are nomadic in nature, the birds responding to both food availability and weather conditions. Flocks will often feed on insects and earthworms taken from farmland fields. During the hardest weather, when the ground is frozen and soil-dwelling invertebrates unavailable, the birds have to turn to opportunities elsewhere. It is during the worst of the weather that they will turn to gardens, raiding berry-producing shrubs and windfall apples. Orchards may also be used during the autumn and winter, from soon after the birds have first arrived until the fruits have gone.

The Fieldfare is a striking bird; larger than a Blackbird this is a robust thrush, boldly marked with a grey head and rump, a chestnut back and chestnut and black wings. The breast is washed buff and marked with dark spots that become larger in size down the flanks. The name itself comes from the Anglo Saxon word ‘feldware’ which literally translates as ‘traveller of the fields’ a reference to both its nomadic nature and preference for open fields.

Although a gregarious species, the Fieldfare may sometimes use its size to defend a food resource, such as a berry-producing shrub or a single windfall apple. This form of food defence is also seen in the Mistle Thrush. Unusually for a thrush, Fieldfares often nest together in a loose colony, where they can then work collectively to see off would-be predators. The birds will dive at the predator, calling loudly and defecating on the intruder, a behaviour that is usually enough to drive the predator away.

As you might expect for such a nomadic species, the Fieldfares that you see here this winter may have spent the previous winter somewhere else entirely. Birds ringed in Britain have, for example, been found in subsequent winters as far away as the Po Delta region of northern Italy. This could make your garden quite a cosmopolitan destination this winter. 

Sea duck makes a rare appearance

I don’t make a habit of rushing off after work to look at rare birds but on this occasion I made an exception. After all, the bird in question had turned up on the nature reserve at work and was the first of its kind to put in an appearance in nearly two decades of my working here. The slightly foggy conditions, coupled with fading light, did not provide much of a window to take the bird in but there it was, a common scoter, sitting quietly alongside the local mallard and tufted duck. The fact that the common scoter is a sea-duck means I rarely get a good view of one anyway, so a bird sat fifty feet away on the flat surface of an old gravel pit was welcome whatever the conditions.

This was a male, jet black in colour with a splash of bright yellow across the bill, and rather smart in appearance. Although common scoter are present off the Norfolk coast throughout the year, it is in the winter months that we see peak numbers with an estimated 5,000 to 6,000 wintering in flocks, known as ‘rafts’, in those areas where the sea is fairly shallow. The association with shallow water underlines the scoter’s foraging requirements, diving to feed on molluscs, like the blue mussel, found on sandy seabeds.

Inland records are uncommon and usually involve birds that are simply resting, taking a break from overland passage. Nationally, such inland records tend to come from our largest waterbodies, particularly more northern reservoirs, so the presence of one on a relatively small gravel pit in the heart of the Brecks was a little unexpected. Mind you, the pits sometimes attract Smew in the coldest winter weather, another sea duck with a rather smart appearance. This bird stuck around for a few days, which again is unusual as most inland records involve birds that are gone within 24 hours.

There is a small British and Irish breeding population, restricted to the north-west fringe and breeding by remote Scottish lochans and Irish limestone lakes, so most of the birds that winter off the Norfolk coast will be from other populations, most likely those breeding in Scandinavia and east into Russia. As is the case with certain of wildfowl, scoter undertake a moult migration, with individuals drawn from over a wide area gathering together at favoured sites to undergo their annual moult. Many will make a substantial overland crossing so the origins of the male that dropped in at the Nunnery Lakes could be many thousands of kilometres from here. Having such a bird arrive on my local patch underlined the pleasure of watching a local site.

Making a living alongside humans

Stillness descends over the town’s margins in the hour before dusk. The paths down by the river fall quiet and no longer echo to the hollow ring of footsteps or the chatter of young voices. This is one of my favourite times of the day and one that delivers a sense of transition, not just from day to night but also from the human-dominated landscape to a more natural one. This is the time when the ducks, Canada geese and swans begin to settle and the rats emerge. All along the footpath, but particularly in those stretches where we humans sit to eat our lunch, the rats can be seen foraging and scavenging. Some seem wary but others, perhaps those that are old hands at making a living alongside people, allow a closer approach.

Rats have a bad press, a legacy perhaps of earlier times when they competed for our food and were associated with the spread of devastating disease. Despite this, I have a soft spot for them and I admire their adaptability, tenacity and success. These are common rats. Although sometimes known as brown rats, their colour is variable and some individuals are very dark, almost black, prompting confusion with the very much rarer black rat, a species now confined to a few isolated and often transient populations within Britain. The common rat is thought to have originated in the vast steppes of central Asia, spreading west across Europe via trade routes and reaching Britain in the early 1700s. Once here, the species spread rapidly, displacing its smaller relative and occupying just about any habitat where natural foods were augmented by those associated with human activity.

Rat society is somewhat more complex than you might at first imagine. Common rats tend to live in colonies, loosely structured affairs that appear to be comprised of small groups, known as clans. Each clan usually comprises of a male or a pair, together with a harem of other individuals. The clan maintains a territory based around a burrow system and one or more food resources. Territory size decreases as the density of rats within a population increases and this leads to a clear dominance hierarchy. Those individuals towards the top of the hierarchy gain greater access to food resources.

The spread of sizes among the individuals that I see by the river indicates a thriving colony and, most likely, one that has had a good year. Breeding takes place throughout the year, the young females sexually mature at just eleven weeks of age, so it is easy to see how this colony has been able to develop and to take the opportunities afforded by our wasteful practices and grubby habits.

Impacts of disease become evident

Many garden feeders have been busy with young goldfinches and greenfinches over recent weeks, suggesting that these small birds might have enjoyed a good breeding season. This news has, however, been tempered by reports of fluffed up and lethargic looking individuals, indicating the presence of disease within the population. The timing of these disease reports is suggestive of finch trichomonosis, the disease that first emerged in 2006 in the West Midlands before turning up in Norfolk the following year. Figures from the BTO Garden BirdWatch (www.bto.org/gbw) show that the impacts of those initial outbreaks are still being felt, at least within greenfinches.

We know about the disease thanks to the work of the Garden Bird Health initiative, a collaborative project involving a number of different organisations, supported by bird food companies, government agencies and private individuals. By pairing BTO Garden BirdWatch volunteers with wildlife veterinarians, it was possible to set up a systematic network to record the occurrence of disease at different sites across the country. Birds found dead could then be examined post-mortem to determine the cause of death and to identify the role, if any, of a disease agent. The project revealed the impact of the trichomonosis outbreak on finches, notably greenfinch and chaffinch, identified the likely origin as spill over from woodpigeons (which carry the Trichomonas parasite) and established the likely route by which it then spread to Scandinavia and continental Europe.

The full, longer-term impacts of the disease in finches have just been published in a paper for which I was an author. Working with colleagues at the Institute of Zoology, the RSPB and elsewhere, we have revealed the extent of losses sustained by the British greenfinch population. As a result of the disease we have lost in excess of 1.5 million greenfinches, a quarter of our breeding population and something that has seen the population decline to levels that were more typical of the 1980s. What is not clear is what will happen next. As I have already mentioned, Trichomonas is present within our woodpigeon population, something that has not stopped it from increasing, so a species can live with the parasite. Perhaps, since this is a new disease in the greenfinch, it will reduce the population through this initial stage but, longer term, it will rumble on at a much lower level.

Having systematic monitoring in place, both of greenfinch populations and disease occurrence, is obviously important. The presence of a network like the Garden Bird Health initiative (which has now ceased for lack of funding) would provide an early warning system for disease in wild birds. With new and emerging diseases a real possibility, let’s hope more funding is secured soon.

Autumn morning

The edge of the wood is bathed in sunshine and I can feel the warmth of the sun’s rays on my face as I emerge from the shadow. At the same time there is just enough of a chill in the breeze to underline that this is autumn, not summer, the strength of the sun’s warmth diminished as we tilt away from her reach. The breeze also carries with it the sweet smell of a bonfire, seemingly out of sight behind the shoulder of land that separates this little valley from the larger one beyond. It is a fine morning to be out and enjoying the clarity of light that autumn always seems to deliver.

It is too early in the day for the local buzzards to be abroad but other birds are much in evidence. A jay, I think it is just the one individual, is transporting acorns across the valley, preparing stores for the months ahead. Up to nine acorns may be carried by the bird during a single flight, the bird having a specially enlarged oesophagus and a liberal supply of saliva, both of which aid transportation. Autumn acorns are also taken by woodpigeons and rooks, so it pays the jay to hide those it can find away from the prying eyes of others. The jay’s store will be tapped throughout the winter, often beginning within a few days of the unhidden supplies being exhausted, and it is amazing to watch the way a jay can pinpoint one of its cached acorns with such ease.

Turning south, I skirt the edge of the wood before tacking left down the slope to the gate at the bottom of the field. My arrival at this gateway into another field sends a scatter of rabbits to their burrows and prompts the noisy flight of a pheasant that had been tucked in close by. With the smell of the bonfire still lingering in my nostrils I can just about pick up the scent of a fox, perhaps an individual that passed this point overnight or just as the dawn was breaking. I wonder if it had been stalking voles in the thick grass that dominates this piece of rough pasture. Deer slots show that the fox was not the only large mammal to have passed this way. One or more roe deer have worked this edge since yesterday’s heavy rain.

The hedgerow still has plenty of green colour, strewn with the dew-sodden webs of many hundreds of spiders and echoing to the wistful notes of a robin. A distant tractor hints that this is a working landscape and that I don’t have it all to myself. It is time to head home.

Some autumn insects

I found the remains of an old lady the other morning. Actually, to be more specific and somewhat less macabre, I found the wings from an old lady moth. The wings were on the floor of a passageway that runs under part of the house and out onto the street. This sheltered spot is well used by brown long-eared bats, which often bring the larger moths into the passage so they can devour them while clinging to the wall. The boldly marked wings of this large moth are easily recognised and they stood out from the remains of other species, taken more commonly by our local bats. The weather has been such recently that I have seen few moths against the kitchen windows of an evening and this makes me wonder if the bats are beginning to find things a little difficult. They have not had a good year by all accounts, with reports of underweight individuals and others seen on the wing during daylight, stressed by the lack of insect prey. It could be difficult for them going into the winter that lies ahead.

I have not experienced a late summer flush of other insects either, with few migrant moths and hoverflies evident in the garden. Not that there has been much late-summer nectar for them – the sedum and nettle-leaved bellflower only coming into bloom over the last few days. At least the sedum has been available for the small influx of red admiral butterflies that has been on the wing during those days when the sun shows against a bright blue sky. Late September and early October can be a reasonable time for insect immigrants; Camberwell beauty, a very impressive butterfly, tends to occur at this time of the year, although in very small numbers. The Camberwell beauty immigrants originate from Denmark, Poland and Sweden, which is why Norfolk delivers the greatest number of records in most years. It has been a while since the last major influx of this species and it is now very unlikely that we will see any influx this year.

There are invertebrates around if you know where to look though and can get out and about ahead of the first frosts. Bush-crickets can still be found in our hedgerows, along with various flies and smaller wasps, and there are plenty of spiders around at the moment, including some of the Tegenaria species that may be encountered dashing across the living-room carpet during the evening. There is a sense, however, that things are winding down, retreating ahead of the approaching winter and readying themselves for a sustained period of inactivity. Every now and then though you might still stumble across something of interest.

Grey Squirrels busy in the garden

I planted several hazels in the garden a number of years ago and they have now reached an age where they produce a crop of nuts each autumn. This has not gone unnoticed by the local squirrels and a scatter of shells, neatly split into two, can be see on the path by each tree. I say ‘squirrels’ but it might be just a single individual, one brave enough to make a living in this highly fragmented urban environment. Up until a couple of years ago the grey squirrel was such a rare visitor to the garden as to attract a surprised comment and, even now, the bird feeders are never touched by this agile forager.

The grey squirrel is a creature that generates a mixed response from us humans. For some it is vermin, a non-native ‘tree-rat’ that has displaced our native red squirrel and brought about the decline of many woodland birds; for others it is a much-loved resident of urban greenspace and one of the few mammals accessible and approachable to a generation of children, growing up divorced from the countryside and its wildlife. The accusations made against the grey squirrel do not always stand up to scrutiny but such is the vitriol delivered in some quarters that claims and counter-claims are rolled out as fact. Take the supposed predation of bird nests for instance. Research has failed to find a link between the decline of woodland bird species and squirrel numbers. In fact, the evidence suggests that grey squirrels are not great predators of nest contents but find only the more exposed, poorly hidden nests, such as those of blackbird and collared dove. If anything, it is the red squirrel that is more of a nest predator than the grey.

Having said this, the grey squirrel remains an introduced species and one that has played a key role in the loss of the red squirrel from most of its former range. Efforts should, quite rightly, be made to prevent the grey squirrel from displacing the red from its remaining haunts and, additionally, be directed to increasing our understanding of the squirrel pox virus and its transmission from grey to red. But what about elsewhere in the UK? Given that the grey squirrel is now so well established across lowland Britain, should we not embrace it as part of our mammal fauna? It is not alone in being an introduction (think of little owl, for example) and its adaptability does deliver an experience of nature into our towns and cities. To see the delight in a child’s face when it watches the antics of an urban squirrel is to sense the contribution this species continues to deliver.

Winds from the east

The last week of September delivered a feast of migrant birds for east coast birdwatchers. With winds from the east, coupled with cloudy and wet weather hanging over the coast, conditions were ideally suited to produce an autumn ‘fall’ of small birds to coastal hedgerows and shelterbelts. Good numbers of redstarts and pied flycatchers were widely reported, together with less common birds like yellow-browed warbler, red-breasted flycatcher and Richard’s pipit.

One of the real joys of birdwatching the Norfolk coast under such conditions is not knowing what you might find while out working a favoured patch of habitat. There is a chance of something unusual, something unexpected and, just occasionally, something rather special. It is just a chance mind you, but the more time that you spend out there the better are the odds of something really good turning up.

It is interesting to think about the birdwatcher’s perception of what is a good bird. While for some it is all about rarity, for others it is the challenge of securing the identification of a bird that is notoriously tricky. For me it is about the sense of place, the bird in the landscape and part of a wider experience. Looking back through my notebooks for this time of the year underlines this. Notes on a barred warbler I found at Kelling, for example, are mixed in with mention of late bush-crickets and the antics of some young common rats, clambering about in the bramble to get at the berries. It is not so much the bird that is the focus but the wider experience.

There are barred warblers about again this autumn and a chance that I might stumble across one, just as I might see young rats or something else, a chance encounter providing a lasting memory. Just being out provides the space to think and relax, to sense your place as the seasons shift and nature responds. Given how much time is spent in an office or in front of a computer, I believe that these moments spent outside have an important role, keeping us rooted in the natural world, reminding us that we are part of something more dynamic and responsive. Computers and televisions direct our gaze to a single point and narrow our horizons but being outside frees us from this, it allows us to gaze around, to be saturated by sounds and sights and to immerse ourselves in something real and tangible. Birdwatching provides an excuse to get out into the countryside and to engage with the natural world, just as walking, riding or volunteering can. It is about extending our horizons, being expansive and engaging with the natural world around us.

Roads take a toll

Over the course of this year, the motor vehicles using our roads will clock up some 300 billion miles of travel between them. With so much traffic on our road network, much of it moving at speed through rural areas, it is little wonder that wildlife casualties are a common sight; forlorn bundles that have been stripped of life and now lay in the gutter. The risk to our nocturnal wildlife is elevated as the autumn evenings begin to draw in and our evening commute home overlaps increasingly with the emergence of owls, deer and foxes.

The barn owl seems particularly susceptible to collision with motor vehicles and a great many, possibly 5,000 to 6,000 individuals, are killed on our roads each year. Much of this toll happens during the autumn, a period when young barn owls, newly independent and inexperienced, are moving away from their natal sites to set up home elsewhere. Over the course of three or four months they will cover a dozen or so kilometres. During this period they will, invariably, encounter a road. Whether or not they are then hit by a lorry or a car depends on a number of different factors. Vehicle speed and traffic volume are important but so are other things, such as whether or not the road is bordered by a hedgerow, whether it has a wide grassy verge and whether it is sunken or raised.

Various studies have revealed that a raised road, running across open country, poses a particular risk because an owl is likely to cross the road at bonnet level. Conversely, a sunken road is more likely to be crossed at a greater height, reducing the risk of collision. Hedgerows work in a similar manner, forcing the bird up and over the road. The presence of grassy verges can be a problem for a different reason. Such verges often support good numbers of field voles, a favoured prey species, and may actually attract owls to the road in those areas where other hunting opportunities are limited. Buffeted by the back draft from a passing lorry, the disoriented owl may then be pulled into the path of the next vehicle and hit.

While this knowledge may help us to plan the management of our roads and their boundary features better, reducing owl mortality, some of the solutions for owls may increase the risk of mortality to other wildlife groups. Replacing a grassy verge with densely-planted shrubs might stop an owl from hunting but it might increase thrush mortality, with birds attracted to the berries that such shrubs often carry. Mitigating the impacts of our busy road network needs careful thought and sensitive planning.