Winter insects hard to find

The winter months offer reduced opportunities for those of us interested in insects and other small creatures. Many species will sit out the cold conditions by burrowing under bark, burying themselves within the leaf litter or by squeezing into a nice dry crack in the brickwork. However, there are still insects and arachnids to be found at this time of the year.

Clearing away dead plant material from one of my borders the other day revealed several caterpillars, overwintering in this form before changing and emerging next year as adult moths. One of the ones I recognised was the caterpillar of the angle shades, a delightful moth that has featured at my moth trap during the summer months. Just below the surface of the soil, as I forked it through, was the large brown pupal case of a hawkmoth. Over two inches in length, it was almost identical to one that I had found last autumn. I managed to overwinter that one in the shed and on 5th June this year an adult privet hawkmoth emerged to be photographed and released. Other moths are still on the wing, including small brown ones that appear at lighted windows late in the evening. These are male winter moths, a species that is unwelcome in those gardens with fruit trees. Broad bands of sticky material can sometimes be seen wrapped around the trunks of fruit trees. These have been fixed there by gardeners, in an effort to trap the almost flightless female winter moth as she attempts to crawl up the trunk to lay her eggs. There are even moths on the wing in the house. Aptly named the white-shouldered house moth, these tiny moths appear on the curtains or at my reading light on most evenings.

There are other small creatures in the house, including two-spotted ladybirds that have hunkered down for the winter, pressed up against the corner of a window frame. A daddy-long-legs spider has taken up residence on the ceiling of the dining room. This spider has long legs and a cylindrical body and, if disturbed, will vibrate its web rapidly – a useful defence against potential predators. Another species of spider remains very much in evidence in the garden. This large spider has taken up residence on my larch-lap fencing. Known by its Latin name of Nuctenea umbratica, the females of this species are rather impressive. Reminiscent of a garden spider, but darker and with a flattened body, Nuctenea spends the day concealed in a crack. Once darkness falls, the spider emerges to wait for prey. Each panel of the fence seems to support seven or eight of these spiders, seemingly forming a healthy population and just one of the species to add interest during winter.

Practical birdwatching

Birdwatching is often regarded as a recreational pastime, an excuse for getting outside and enjoying the Norfolk countryside. However, it can also serve a practical purpose by providing valuable information on the distribution and numbers of Norfolk’s birds. The submission of records gathered during recreational birdwatching, to the County Bird Recorder or to national schemes like BirdTrack (www.birdtrack.net), is something that many birdwatchers do routinely. However, fewer birdwatchers take part in the systematic surveys that underpin much of our knowledge about the changing fortunes of our avifauna. This is a shame, not least because participating in such surveys can lead you to visiting parts of the county that you would not otherwise have gone to. Last weekend, for instance, I visited a survey square that I had been jointly allocated for the Norfolk Bird Atlas – a project that aims to map the distribution of birds across the county. This took me to part of Breckland that I had only previously viewed in passing.  Sat between the A11 and Bridgham, the landscape was a mixture of arable farmland, pasture and small blocks of woodland.

Although there had not been any overnight frost, it was damp and decidedly chilly but at least we would be on the move in order to cover all the ground. The aim was simple, to record the birds that we saw within the square and it was not long before our tally began to rise. Within a few minutes we encountered a flock of about 30 linnets, delightful little finches that were once popular as cage birds. Seen in flight, the flock was heading for one of the little blocks of game cover, rich in the small seeds favoured by these birds. There were other finches too: chaffinches and greenfinches in good numbers, fewer goldfinches and a single bullfinch. The bullfinch can be difficult to connect with, perhaps because it is rather secretive in its habits and has such a soft call note. We were also treated to a couple of winter visitors, with a handful of fieldfares and redwings, though nowhere near the number we might expect to see later in the winter. The highlight of the morning was the sight of a barn owl. A pale individual, probably a male, was perched in the lower branches of an oak. Effortlessly, the bird dropped from the branch to pounce on something in grass, where it remained for half a minute before rising up into nearby tree. A brief view but nonetheless sufficient reward for our efforts. After an early start, and nearly five hours in the field, we had some very useful data for the Atlas and had seen some really nice birds, making the survey work a pleasurable way of spending Sunday morning

Long nights hard on small birds

The long nights that we experience at this time of year can make things difficult for many of our birds. A combination of low temperature, reduced amounts of daylight in which to find food, and a general decline in the amount of food available, can all have a dramatic impact on smaller species. Small birds may need to expend more energy to keep warm and, with only small reserves of body fat, they have to spend much of a typical winter’s day searching for food. This food is vital to replace losses from the night before and to prepare for the night ahead. Great tits may easily lose five percent of their body weight overnight, with the amount of weight lost being greatest during periods of cold weather.

Watching my bird feeders has revealed a pattern to the order in which the different species arrive in the morning. As one of some 2,000 licensed bird ringers nationwide, I am frequently up before dawn to set the nets in which I catch small birds for ringing. At this time of day, I can already hear the calls of blackbirds and robins up and about before it is truly light. With the nets set, I operate a regular pattern of checking and emptying the nets every 20 minutes or so, fitting rings and taking various measurements before releasing the birds. The first birds to be caught are usually blackbirds and other thrushes, followed by various tits and the occasional dunnock. It is not until an hour or so after dawn that the greenfinches, goldfinches and chaffinches begin to appear in any numbers. Birds continue to arrive to feed through until mid-morning then it all goes rather quiet, with numbers not increasing again until the hour or so before dusk, presumably when individuals come in to top up before going to roost.

Intuitively, you might expect those species that most urgently need to top up their fat reserves to arrive first but other factors also come into play. For example, roosting behaviour may be important. Some species roost communally, sharing body warmth and reducing the amount of energy they have to expend to keep warm. While wrens can use nestboxes or roosting pouches, long-tailed tits prefer to roost together on a branch in the centre of a thicket. Dominance also plays a role, with less dominant species forced to feed at times when feeders are not being dominated by more aggressive birds like greenfinch or starling. Such factors influence the basic pattern and will change over time as birds respond to changing weather conditions. Recent nights have been relatively mild but, as we move further into the winter, lower temperatures may bring birds to our feeders that much earlier relative to dawn.

Front row seat for a Norfolk spectacle

The raised earthen bank at Stubb Mill, Hickling, may seem an unlikely place from which to watch for birds of prey and other wildlife. Scrub, reeds and rough grassland stretch away into the distance and on a cold winter’s afternoon it can all seem rather bleak, not to mention cold. However, at this time of the year the watchpoint provides an excellent opportunity for viewing harriers, merlin and common crane as the birds come in to roost just before dusk. With very little shelter from the elements, the watchpoint is best visited on a bright afternoon. The birds will still arrive in the rain but tend to hunker down quite quickly and, with poor light, there is not much of a spectacle. However, in the good light of a bright December afternoon, you may be spoilt by views of hunting harriers or of merlin and Sparrowhawk mobbing their larger cousins. There is even the chance of seeing a short-eared owl or peregrine.

Most observers tend to arrive an hour or so before dusk but I prefer to arrive well before this. One of the reasons for arriving so early is to be able to watch Chinese water deer in good light. This introduced species has established a sizeable population within the county, centred on the Broads, but seemingly spreading north and west to other sites. Most of the Chinese water deer that I encounter elsewhere within the county are either ones that have been killed in collision with motorcars or are brief glimpses of live individuals disappearing into thick vegetation. Stubb Mill has proved to be one of the best places to get good views of these small deer, perhaps because you are sitting on a bank looking down on the surrounding habitat. Slightly larger in size than a muntjac, the Chinese water deer reminds me of a roe deer in its posture and movements, though smaller in size. First introduced at Woburn Park in the early 1900s, several established populations occur in Bedfordshire, Cambridgeshire and Norfolk where they favour mixed reedbed and woodland habitats. They are cautious animals and if alarmed will run off, flinging up their hind legs as they go.

Perhaps I have been fortunate in my visits to Stubb Mill. Each time I have been treated to close views of the deer, followed by the spectacle of hen and marsh harriers quartering the ground or loafing about in scrub. These have been accompanied by views of kestrel, sparrowhawk and merlin on virtually every occasion, with the whole afternoon often rounded off by the arrival of the local cranes. Having so many special birds and animals in one place makes this a site that everyone interested in Norfolk’s wildlife should visit at least once.

Immigrants on the increase

A visit to Norfolk’s coastal saltmarshes will often reward the observer with views of one of the county’s newest breeding species – the little egret. Smaller than the more familiar grey heron, the little egret makes a striking sight, with its white plumage, dark legs and yellow feet. When hunting in shallow water, the egret will edge slowly forward, making frequent stops and taking care not to scare off its prey. From time to time a feeding bird will extend a leg and vibrate it rapidly. This ‘stirring’ motion is used to disturb fish or invertebrates hiding in the mud.

Little egrets were rare vagrants to Britain for many decades, following widespread persecution as a consequence of the Victorian trade in their feathers. During the breeding season, adult little egrets have two, sometimes three, long plumes on their crown and they also sport elongated feathers elsewhere on the body, most notably on the chest and back. It is these feathers that were prized by the Victorians. Between 1952 and 1988, there were just 26 records of this species from Norfolk, with most thought to be spring migrants that had overshot their European breeding grounds. Then, suddenly in 1989, there was an unprecedented influx, though only three of the 120 or so that arrived made it to Norfolk. Over the following years, breeding was noted at sites along the south coast of England and the population started to expand rapidly in both size and distribution. With increasing numbers of little egrets being seen in Norfolk and with the establishment of regular roost sites at Holkham and Titchwell, it was clear that breeding would soon take place within the county. In summer 2002, breeding did occur at two sites, with eight pairs producing 19 young. Last year, 2004, some 55 pairs were thought to have produced 152 young – a staggering increase in such a short space of time.

Given the recent success of the little egret, it is fitting to see it feature on the cover of the recently published Norfolk Bird & Mammal Report for 2004, which, incidentally, contains an article on the species by Ron Harold and Andrew Bloomfield. It also features on the cover of the Wetland Bird Survey Report for 2003/04, published annually by the British Trust for Ornithology, the Wildfowl & Wetlands Trust, RSPB and the Joint Nature Conservation Committee. The Wetland Bird Survey is the national monitoring scheme for non-breeding waterbirds (such as waders, ducks, geese, grebes and herons) and, with annual count information going back to 1966, it has been an invaluable tool for charting the increases and decreases of our various waterbird species, including the sudden rise of Norfolk’s little egrets.

The Woodcock moon

It was bitterly cold the other morning as I drove the dogs out to the forest. Still dark, the headlights of the car picked out the distinctive squat shape of a woodcock settled in the middle of a quiet forest road. I brought the car to a gentle stop some twenty feet or so from the bird. Dazzled by the headlights, the woodcock remained motionless, affording me the opportunity to admire what is surely the most handsome of our wading birds. It’s head, back and wings are camouflaged by a mottle of browns and greys, while broken horizontal bars cross its paler chest. As I dipped the lights, the bird was up in the air and gone. This had not been my only view of this species over recent weeks. On other mornings I had seen the distinctive silhouette of a woodcock set against the dawn sky.

This highly secretive species is somewhat unusual for a wading bird. Active at night and most readily seen around dawn and dusk, it is adapted for a life predominantly spent within broad-leaved woodland. Here, in the south-western part of Norfolk, the woodcock can be found breeding and wintering in young conifer plantations, moving out into the surrounding pastureland to feed on earthworms and other soil-living invertebrates taken from the surface and top layers of the soil. The bird uses its long and highly sensitive bill to probe for prey.

Although the woodcock which breed here in summer are thought to be largely sedentary in their habits, birds from further north are migratory, with many thousands arriving to spend the winter here. Those birds that arrive in Norfolk from the second half of October will have come from Finland, Latvia and Russia. Such arrivals may continue into late December but go largely unnoticed because they arrive at night. Tradition has it that they all arrive together, some time around all hallows, following a change in the wind direction and close to a full moon. While it appears that a northerly or north-easterly wind is associated with the arrival of these winter visitors, there does not seem to be any evidence that the phase of the moon exerts an influence. However, such is the strength of this tradition that wildfowlers may refer to autumn full moons as ‘woodcock moons’. It is not just with the moon that the woodcock has been associated. The ease with which woodcock could be caught, typically by erecting nets at dawn or dusk across rides cut into a block of woodland, led to the notion that the species was rather stupid. This, in turn, led to the use of the term ‘woodcock’ as a synonym for slow-wittedness in a person – a harsh association for such a handsome bird.

Highlights of a quiet afternoon birding

Dropping down from the ridge running west from Burnham Market you get a wonderful view over Titchwell marsh. On a bright November Sunday, you can see dozens of birdwatchers making their way to the hides that overlook the scrapes on Titchwell Reserve. At this time of year there are many different birds to be seen from these hides and, with lots of eyes scanning the flocks of waders and wildfowl, there is always the chance of something rare or interesting. But today I want to avoid the bustle of the crowds and find some solitude worthy of such a clear day. For me, one place to do this is at Gypsy Lane. Situated to the east of Titchwell, a small lay-by marks the entrance to a narrow lane running north to the coast and passing through a sequence of habitats.

The first part of the track is bordered by a strip of linear woodland, with a range of bushes and shrubs, from which the soft call-notes of foraging birds can be heard. It is well worth pausing to watch and listen as mixed feeding flocks, often of tits and late warblers, work their way past in search of insects and seeds. On this occasion there is no hoped-for rarity, like a Pallas’s warbler, but there are goldcrests in with the tits. As the trees thin, there is a glimpse of two jays, another bird that, like the goldcrest, is much in evidence this autumn. There are also glimpses out across Titchwell Marsh, over which hunting harriers may sometimes be seen – though not today. Then it is out from the cover of the woodland and onto the bank that puts you above the reeds, pools and saltmarshes which flank either side.

Almost immediately I can hear the scolding call of a wren from low down in the vegetation just a few metres away. Further off, I can hear the ringing calls of a small party of bearded tits as they move excitedly through the tops of the reeds. These are one of the birds I have come to see. Standing by my scope, I wait and listen as they move closer, slight movements in the reeds giving away their location. Finally they show themselves, brightly coloured and almost comical in appearance, these delightful little birds are always a joy to watch. Although they are scarce (nationally there are about 500 pairs), the counties of Norfolk, Suffolk and Essex hold about 40% of the breeding population and provide some of the best opportunities to see these birds. Only part way through my walk, and with the prospect of more birds to see, the journey up to the coast has already proved worthwhile, something I can reflect on over tea.

Be prepared for busy bird tables

There was ice on the car windscreen the other morning and a definite chill in the air. Another indication of the drop in temperature was an increase in the numbers of birds visiting my garden feeding station. In with the regular greenfinches, were chaffinches, blue tits and coal tits, attracted by the sunflower hearts that I provide throughout the year. Providing food in this way gives a good indication of the numbers of birds around and of the availability of ‘natural’ food in the wider countryside. Towards the end of summer there is a noticeable drop in the numbers of birds visiting the garden, as birds that may have been breeding locally move out into the surrounding farmland and woodland to exploit the autumn bounty of fruits and seeds. Evidence from the 16,000 gardens that participate in the British Trust for Ornithology’s Garden BirdWatch scheme shows that this autumn trough is a national feature, repeated in gardens up and down the country. It is only when the bounty begins to decline, that the birds turn to gardens and the food that we provide.

Just how early into the winter birds like siskins, chaffinches and bramblings move into gardens is, in part, dependent on the size of the seed crop produced by trees like beech and sitka spruce. In some years, when the seed crop is particularly large, there is little need for these birds to visit gardens but in those years when seed is scarce, they can arrive early and in large numbers. The size of the seed crops of these two tree species follows a roughly four-yearly cycle, a strategy that enables the trees to reduce the impacts of seed predators on their precious seeds, with years of peak seed production followed by a number of years of much smaller crops. It just so happens that this year the quantities of beech seed (known as beechmast) and spruce cones are both small, something that has seen siskins arriving in gardens across East Anglia earlier than they would normally appear. This hints at a busy winter ahead, with large numbers of finches usng garden feeding stations. Because there tends to be a degree of synchrony in the size of the seed crop across large areas, we are also likely to see increased numbers of birds arriving here from Scandinavian forests. If, as the weather forecasters are predicting, we end up with a severe winter then this too will increase the numbers of birds visiting gardens. Joining the finches will come farmland buntings and thrushes, seeking the food needed to get them through the worst of the winter weather. So now is the time to stock up on birdfood, prepare yourself for the winter ahead and the sight of busy bird tables.

A four-spotted two-spot

We had a visitor to our office this week, quite possibly attracted by the lights that illuminate our work on these increasingly dark afternoons. The visitor in question was a ladybird, a two-spotted ladybird to be precise. This species is one of our most familiar ladybirds, easily recognised and seemingly as at home in urban areas as it is in the wider countryside. Two-spotted ladybirds often bring themselves to our attention through their habit of hibernating around our homes, even appearing indoors during spring. They are good creatures to have around if, like me, you are a bit of a gardener. Two-spotted ladybirds have a real taste for aphids, feeding on a range of different species including the black ones that are associated with leaf curl on cherry trees.

I should not have been surprised, therefore, to encounter one inside at this time of year. What did cause me to raise an eyebrow though was the fact that this particular individual was of the melanic form. In melanic individuals, the red and black colouration is reversed. So, instead of black spots on a red background there were red spots on a black background. Not only this, but instead of the two spots that give this species its name there were four! (It is worth mentioning that some melanic forms of this species have six red spots.) One of the surprising features of ladybirds is just how much variation in colour and pattern there may be within a species. While some species are pretty uniform in their appearance, others are very variable and the two-spotted ladybird is one of the most variable of all. The most common form of two-spotted ladybird is the one with a large black spot, set against a red background, on each wingcase. The melanic form is far less common. One recent study suggested that within a population about 4% of individuals would be melanic. Because this variability in colour and pattern has a genetic basis, you sometimes find clusters of a particular colour form within a small area. However, this was the first such individual I had encountered locally. One of the problems, for a budding entomologist at least, with having such variability is that it can make it more difficult to identify a particular species. The individual I had found was superficially similar to a pine ladybird but lacked the characteristic turned up edges to its wingcases shown by the latter species. I did take the ladybird home though, to double-check my initial identification with a hand lens. Seemingly underwhelmed by the amount of attention it attracted, the ladybird was released by my shed in the hope that it would find a safe place to spend the winter.

Master of the reedbeds

Sunday morning found me settled in Dawkes hide, looking north across the Norfolk Wildlife Trust’s Cley Marshes reserve. It was early enough for the hide to be relatively still and the only other birdwatchers present were a handful of regulars. Judging by the conversation, these ‘old boys’ had been coming here for many years, enjoying the wide range of birds attracted by the reserve’s position on the North Norfolk coast. As I scanned the reed-fringed pools and wet grassland, passing over teal, shoveler, gadwall and resting waders, my gaze settled on the familiar shape of a harrier working the edge of the reeds in search of prey. As the bird turned, the sun caught on the golden cap – a marsh harrier and a real master of East Anglia’s reedbeds.

With a little patience, good views of this wonderful raptor are virtually guaranteed at a number of sites across Norfolk and Suffolk. Yet, the fortunes of this species have undergone dramatic change over the last 200 years. In the early 1800s, the marsh harrier was common across much of Britain and Ireland but widespread persecution led to a rapid and well-documented decline. By the late 1870s the species was restricted to the Norfolk Broads. Over the next thirty years there were a number of failed nesting attempts, the birds falling foul of persecution and the unwelcome attentions of egg collectors, and the ‘last’ recorded nesting attempt was in 1899. It was not until 1921 that a successful attempt was again documented and a recovery of sorts began. With the exception of 1937 and 1940, nesting attempts have been recorded every year since 1928, although there was another decline in breeding numbers in the 1960s. This was attributed to the use of organochlorine pesticides, which hit predatory birds hard because of their position at the top of a contaminated food chain.

Most of the recovery has happened since the mid-1970s and there are now thought to be at least 200 breeding females nationally. Male marsh harriers can form bigamous relationships, so the number of breeding females is the most appropriate unit by which to measure the population. Two important changes in the behaviour of this species may have contributed to the population increase. First is the tendency for some individuals to overwinter here, rather than make a migratory journey south to wintering grounds in southern Europe and Africa. The second change has been for birds to nest away from reedbeds, moving into arable crops, a habit that was first documented in west Norfolk in 1982. The skill of these birds when hunting and the way in which they use the wind to work their way across the ground make them a delight to watch, especially from a comfortable hide in good company.

What is in a name?

As I opened the door the night before last, I was delighted to see a small beetle scurry in across the threshold. Metallic blue in colour and roughly a centimetre in length, I recognised it as Leistus spinibarbis, a ground beetle that I had first learnt to identify several years ago thanks to the tutorage of Brian Eversham and Mark Telfer. There is nothing particularly special about Leistus spinibarbis; it is not rare but enjoys a distribution that takes it from Britain, across Europe and into Africa. What is interesting, though, is that this species lacks a common name. Like virtually all of the other 360 or so ground beetles found in Britain and Ireland (and the vast majority of invertebrates worldwide) it is known simply by its scientific name.

Scientific names form the basis by which species are classified. They are necessary because the names given to individual species must be understood across the World. As such, they represent a common language by which researchers in different countries can be sure that they are referring to the same species. The application of scientific names is governed by an international code to which the naming of newly discovered species must adhere. The name Leistus spinibarbis follows what is known as the binomial system, first applied by the naturalist Carl Linnaeus in 1758. Under this system, the scientific name consists of two components: the first (Leistus) referring to the genus (a taxonomic subdivision of a family) and the second to the species (spinibarbis). There are five other closely related species of Leistus in Britain, all belonging to the same genus but each with its own individual species name.

Many people find scientific names off-putting, not least because they can be cumbersome in their construction. Try getting your tongue around Scybalicus oblongiusculus (another ground beetle)! The use of ‘common’ or vernacular names, like ‘blackbird’ or ‘robin’, is a good compromise but these only tend to work within a single country since they are intrinsically linked to the local language and culture. Having two parallel systems usually works fine and, as research and writer, I use both, switching between the two depending on audience. However, the lack of a common name may deter people from becoming more acquainted with a species. Understandably, if you are uncomfortable with the name of a species, then you are less likely to take a more detailed interest in it. This is unfortunate, particularly in the case of Leistus spinibarbis, which is superbly adapted for feeding on springtails. It’s jaws have a wide flange running along the edge, something that Mark Telfer suggested would suit a common name like ‘Blue Flange-mouth’. Maybe having such a name would help raise the profile of this delightful little beetle.

20 pence flight from Norway

There is something special about birdwatching on the east coast during autumn. You get a real sense that vast numbers of birds are on the move, streaming into the country from across the North Sea. This was something that was brought home to me the other day as I walked the lanes around Happisburgh, enjoying the bright, clear weather that carries just enough edge to let you know that summer is truly over. Small groups of blackbirds were passing overhead, together with smaller numbers of redwings and occasional fieldfares. From the hedgerows, more ragged here than elsewhere in the county, came the high-pitched contact calls of diminutive goldcrests, busy searching for insects. Even though goldcrests breed in Britain (there are some 600,000 pairs nationally), these particular individuals were more likely to be migrants, freshly arrived from Scandinavia or western Russia.

As well as being the smallest British bird, the goldcrest has the distinction of being one of the lightest birds anywhere in the world to make regular sea crossings as part of an annual migration. For a bird that weighs roughly the same as a twenty pence piece (about 5.3 grams) such movements are truly remarkable. In some years, bushes and hedgerows at east coast sites may be literally ‘dripping’ with exhausted goldcrests during autumn. These are birds that must operate very close to their physiological limits. Information generated from bird ringing schemes, operating across Europe, has revealed that goldcrests breeding in the northernmost boreal forests are almost completely migratory in their behaviour. Birds from breeding populations situated further south are more likely to remain where they are to overwinter. Some coastal populations on the edge of the Arctic Circle in Norway also remain close to their breeding grounds in winter. By doing so, they have to cope with severe cold and nights that are 18 hours long. It has been calculated that these birds may burn off a fifth of their body weight each night, just to maintain their body temperature at a safe operating level!

This autumn has seen very large numbers of these tiny birds arriving on our shores. Even though the main arrival took place in the second half of October, and was centred on the Yorkshire and Lincolnshire coast, there still appear to be good numbers within East Anglia. Most mornings, while exercising my overly energetic spaniels in Thetford Forest, I encounter goldcrests foraging among the conifers. As if to reinforce the origins of some of these birds, I received a report last week of one individual caught within a mile or so of Thetford which sported a Norwegian ring. One wonders where the individuals I had seen at Happisburgh were from.