Saturday, 15 December 2007

'Christmas trees' provide a new home


Several of the conifers growing in our garden when I was young were old Christmas trees, planted out having served their festive purpose. As such, I used to refer to any suitably shaped conifer, regardless of origin, as a Christmas tree. Today, a wide range of conifers are used for Christmas trees and, indeed, for other ornamental purposes. One of these, the leyland cypress, has made the headlines on occasion when neighbours have fallen out of over the size of hedge this tree can achieve. The Leyland cypress was first created as a hybrid, by crossing Monterey and nootka cypress, but it now occurs alongside many other cultivars.

The widespread establishment of these new cypresses has opened up opportunities for a number of different insect species, including several moths. Juniper is our only native member of the cupressaceae (the family of conifers which includes the cypresses) but other members are native to southern Europe and these support a number of moth species not originally found in Britain. However, over the last 60 years several species have established themselves here. The first of these reached us in 1951, when a Dr Blair discovered Blair’s shoulder-knot feeding on a Monterey cypress on the Isle of Wight. By the 1960s this species had reached the mainland and began to spread inland. It now occurs across much of Britain, reaching as far north as Tyneside and southwest Scotland. Blair’s shoulder-knot had been extending its range from the Mediterranean around the Atlantic coast of France and, from there, it was a short hop across the English Channel.

Other species to reach us include the cypress pug and the cypress carpet, arriving in 1955 and 1984 respectively. Although now well-established, both species have failed to penetrate very far north and are restricted to the extreme south of England because they are prone to winter frosts. A number of smaller moths, just a few millimetres in length, have also reached our shores to exploit the new cypress resource. One of these, Argyresthia trifasciata, is a stunning little fellow, with golden wings across which run three white bands. Its caterpillars feed within conifer shoots and the shoot tips soon turn brown, leaving a clear sign that the moth has colonised a tree. Although such species may have been able to extend their European range northwards thanks to global climate change, they could not survive here without the presence of the cypresses. Other species have been assisted by the international trade in conifers, piggy-backing on trees imported from North America. The cypress tip moth that is established around Ipswich almost certainly arrived this way. At least one native species has been reported feeding on cypress and others may follow.

Friday, 14 December 2007

Red in tooth and claw


I am fascinated by predators and our perceptions of them, the way in which people can react so aggressively to the presence of a sparrowhawk in their garden or to the sight of a magpie with a chick in its bill. Many of us seem unable to let nature act out its daily performance without interfering or choosing sides. Anger at the loss of a blue tit to a sparrowhawk is not mirrored when a blue tit predates a caterpillar or a blackbird pulls up and dispatches an earthworm. Why is this? There is no ecological difference between these various acts of predation, so why should we accept one and challenge another? I think that it has a great deal to do with our perceptions and the affinities we establish with certain creatures, while largely ignoring many thousands of others. Examine any list of our favourite animals and the chances are that those at the top of the list will be furred or feathered. Even within birds and mammals, we have our favourites. For example, while magpies are widely disliked for their predation of young birds and eggs, we are delighted to see a great spotted woodpecker, even though it is also a predator of nesting birds. Great spotted woodpeckers regularly break into tit nest boxes, first tapping the box to elicit a response from the nestlings (thus determining that it is occupied) and then drilling in to extract a meal.

It is essential to understand that nature is “red in tooth and claw”; it is cruel and vicious and unsympathetic. We should not impose our moral values onto wild creatures but instead accept that they are following their natural instincts. Accepting predation in all its forms is, I believe, an important step towards reconnecting with the natural world. By imposing our views of what is and is not acceptable we are distancing ourselves, setting ourselves apart in a way that is unhealthy and, potentially, unsustainable.

A failure to understand the ways in which populations of different species interact, through processes like predation, can reinforce misguided views about the nature of predation. I have received no end of letters over the years from people who have been quick to point an accusatory finger at birds of prey, calling for a cull of their numbers to halt the decline in various songbird populations. Yet, there is no scientific evidence to implicate predators in the declines of our songbirds. The evidence that is there supports the hypothesis that it is habitat change (through agricultural intensification and changing woodland management practices) that is the root cause. However, the act of predation unsettles us and it is easy for some to blame avian predators.

Thursday, 13 December 2007

December is a good month to see our smallest duck


There is something rather special about a visit to the North Norfolk coast at this time of the year. The coastal marshes and flooded pastures support huge numbers of wintering wildfowl, and it is quite something to see and hear the feeding flocks of ducks and geese. Such winter visitors include the diminutive teal, our smallest native duck and one of my favourite birds. Its clear, ringing whistle is such a characteristic sound; shorter and with a harder edge than the soft whistles produced by the wigeon alongside which teal are often found. Flocks of at least 1,500 individuals may be seen at Cley, while another Norfolk Wildlife Trust reserve, Hickling Broad, regularly supports up to 3,000 birds. Far smaller numbers of teal occupy waterbodies that are situated well inland. However, I have seen them on the Breckland meres and on smaller pools spread across parts of the southwest of the county.

Although small numbers of teal breed in Norfolk, our wintering population is largely drawn from birds that have bred in Iceland, Scandinavia, the Baltic States and east into Siberia, making Britain an internationally important site for the species. Other teal winter as far south as North Africa and up the Nile Valley.

Watch a flock of feeding teal and it soon becomes apparent that they favour shallow water, dabbling to feed on the seeds of aquatic plants (these make up some 75% of the winter diet) and small invertebrates. In some areas, though, they have taken to using winter stubbles. This reliance upon shallow water makes them vulnerable to severe winter weather. Low temperatures and the freezing over of the shallows drives the birds to undertake cold weather movements, taking them further south and west in search of open water. Such movements usually drive our birds down into western france and Spain, where they occupy sites that are only important when the weather is particularly bad further north. Although a quarry species and popular with waterfowlers, temporary bans on shooting during severe weather help teal to feed on unfrozen waterbodies in relative peace. This can make an important difference to birds that are energetically stressed and needing to maximise food intake.

Assuming that we do not get a hard winter, then many of the teal presently in Norfolk will remain here until at least the end of February, when the spring departures begin. Since the spring migration is something of a protracted affair, many of the birds will still be here in late March or even early April. Arrivals back on the breeding grounds, and indeed the breeding grounds chosen, will depend on local weather conditions, again highlighting the fluidity of movements shown by this delightful species.

Wednesday, 12 December 2007

A late butterfly


The other afternoon, whilst walking home for lunch, I came across a red admiral butterfly, flying strongly above a high stone wall. This is my latest record for an active red admiral but perhaps it should not be that unexpected. The red admiral seems to be responding to global climate change, with very many more individuals seen on the wing in Britain now than was the case back in the 1970s. Some of these individuals are overwintering successfully as adults, with reports of territorial males and egg-laying taking place in the first three months of the year. This is particularly interesting because the red admiral is really a migrant visitor, breeding here in summer but thought unable to survive our winters. The first of the summer migrants reach us from the end of March, arriving from North Africa and the warmer Mediterranean islands. This means that those seen in January and February are likely to have overwintered here. Larger numbers of migrants arrive in late May or June, with these individuals originating from Spain and Portugal. The summer arrivals lay their eggs on nettles; the larvae that emerge making a simple tent by folding over the leaf and then holding it in place with silk. It is these youngsters that, having undergone the amazing transformation of metamorphosis, are seen on the wing as adults from August to October, when peak numbers occur.

From mid-August, perhaps triggered by shortening day-length, the strong-flying adults begin to move south. Large numbers often congregate in the extreme southern parts of England before crossing the English Channel. Yet, over recent years, increasing numbers have been seen on the wing later into the year to the extent that November records have become commonplace in some parts. Unlike certain other species, which as residents do overwinter here as adults, the red admirals on the wing so late into the winter usually perish. While peacocks, brimstones and small tortoiseshells choose sheltered sites for hibernation, the red admirals seem to settle on tree trunks (a site used for roosting at other times of the year). This would seem to make them more vulnerable to predators, parasites and the worst of the winter weather. Red admirals have also been reported overwintering as eggs, larvae and pupae and, in all cases, the development time of each particular stage is slowed. Once again, this may leave them open to predators and disease, leading to high losses and reducing the chances of successful overwintering.

No doubt things are changing, with more red admirals overwintering. However, since spring abundance is not correlated with the number seen late in the autumn, it seems that our increasing summer numbers result from migrants rather than those that try to overwinter.

Tuesday, 11 December 2007

Creating a living landscape


Norfolk boasts an impressive array of nature reserves, from the well known coastal marshes frequented by birdwatchers through to small blocks of woodland tucked away in the centre of the county. Each reserve tends to be managed in a particular way and benefits a particular suite of species, with some reserves managed for just one or two high profile species. Although there is no questioning the role and value of such reserves, I have sometimes felt a little uneasy about the way in which we seem to partition nature off from the wider countryside. Sure, we can defend our efforts by saying that we are seeking to protect wildlife in these few remain patches of habitat but is this enough? By accepting these small and often isolated patches as being for nature, are we not just allowing the desecration of the remaining countryside? There is a danger that nature reserves simply reinforce the perception that nature can only occur where we allow it and, ultimately, this divorces us from the world around us.

It is welcome news, then, that the Wildlife Trusts have just announced a new approach to conserving and protecting our wildlife. Accepting that many nature reserves will not be sustainable in the longer term, not least because of the effects of global climate change, the Wildlife Trusts have launched a series of landscape scale projects under the banner of ‘A Living Landscape’. This approach adopts a different philosophy to that employed for most current nature reserves by seeking to protect landscape-scale features. By definition this approach requires a thorough understanding of what constitutes a particular landscape in terms of its wildlife, habitats, geology and geography. With this knowledge it should be possible to determine how the various habitats associated with the landscape can be enhanced or restored to create a landscape that is sustainable over the longer term. It is, very much, a holistic approach. In the formerly well-wooded low Weald of Sussex, the local wildlife trust is working to enhance the fragments of remaining ancient woodland, by re-establishing lost woodland and connecting the isolated blocks together. A similar approach is being adopted by the wildlife trust in Cambridgeshire, where the Great Fen project aims to restore some 3,700 hectares of lost fenland. With time, such projects should benefit a great number  of species and, importantly, allow them to exist within a landscape that is viable over the longer term.

Of course, a landscape level approach has one other clear benefit; it reinforces the view that we need to live sustainably within a landscape. This means that such projects need to involve landowners, integrate with wider government policy and involve local communities. Only then will we have a living landscape.

Monday, 10 December 2007

A red-letter day


It has been something of a red-letter day, thanks to a pair of long overdue encounters on my local patch. As normal, I left home in darkness, heading out to the forest where I exercise the dogs with an early morning run. Passing through the wedge of arable land that sits between town and forest I stumbled across a barn owl. Its pale form stood out from the disappearing darkness like some wondrous spirit, as if absorbing the slowly-brightening half-light of early morning. This bird was so pale that it had to be a male and I had inadvertently flushed it from the rather battered hedgerow that bordered the road. On the wing the bird became more ethereal, seemingly all wing and very little body. The broad, rounded wings enable the owl to move through the air with an almost silent and effortless ease; many a time when botanising I have been surprised by a barn owl passing silently over my head, quartering the ground for small mammal prey. To see such a bird at close quarters, especially in the soft, understated light of daybreak, always sends a shiver through my body. It is a shiver of delight and not one of fear, even though owls have always been associated with the supernatural and sometimes feared as harbingers of ill-fortune. However, as this owl slipped away across the field and out of view it brought me not ill-luck but good fortune.

Less than an hour later, as I was rounding a bend in the forest ride, the dogs stiffened and stood erect, their eyes fixed ahead. Catching up with them, my gaze fell upon a group of four fallow deer, the first I had seen in this patch of forest for many years and the first live ones I had encountered for some months (there is a stretch of road to the south of Thetford where I often see the sad remains of fallow hit by motor vehicles). These four were all does, three of the dark form and one of the white form more often seen in deer parks. The dogs know well enough not to chase but were clearly unsettled by the deer. The fallow were equally unsure, standing quite still and watching us intently; the first movement from me or the dogs and they would be off. We could only have remained motionless for a dozen or so seconds but the encounter seemed timeless and I was able to take in the delicate beauty of their form and the deep intensity of their stares. Then they were gone, off the track and into the undergrowth, and the moment had passed. To have two such encounters made it a very special day.

Saturday, 17 November 2007

I can't see the trees for the wood


Spurred on by Richard Mabey’s new book ‘Beechcombings: The narratives of trees’, I have re-evaluated my relationship with woodland. I was raised on the Surrey-Sussex border, amid the verdant growth of deciduous woodland that extends over a large part of the Wealden landscape. Trees provided me with tools for play; they supported the insects and birds with which I became fascinated, yet all the time they remained a backdrop to my progression towards maturity. They were such an integral part of my childhood that I took them for granted and ignored them, relegating them to the role of scenery, in front of which I played out my youth.

Richard’s book has made me realise the extent to which I have underplayed the beauty and value of trees. I am not as confident in their identification as I am with birds, insects and other wildlife and, by not knowing them, perhaps I appreciate them far less than I should. When I first left Surrey I was struck by how open a landscape could be, perhaps no more so than in the fenlands of Norfolk. Separation from the woodland within which I had been so comfortable, and the feeling of loss that came with it, underlined the importance of woodland to me. However, it was the woodland (this community of mixed species and forms) that I missed, and I still did not have a relationship with individual species of tree. This has changed, a response to reading of Richard’s own experiences with woodland, of his strong bond with the beech and the role that particular trees have played in the lives of other people across the country. Even though individual trees, because of their size and longevity, genuinely do provide a backdrop to our lives, it is possible (perhaps even essential) that we also regard them as living organisms.

In this age of regimented and man-made materials, we are becoming increasingly divorced from natural products, like wood, and the inherent variation in quality and end use towards which such products may be put. The varying qualities of different woods, how they can be worked, how they burn and what they are best suited for, help define the qualities of the trees themselves – for example, the sturdy oak, the flexible willow. To properly understand them, you need to appreciate these qualities and take time to study the form of individual trees within the landscape. Many will have decades of history associated with them and knowing this (plus knowing that this history will continue to accumulate long after you are gone) soon brings the tree out from the background and into the central focus. It becomes a living individual, just like you.

Friday, 16 November 2007

A walk with a purpose


My early morning walks through the forest have taken on a new purpose. In addition to exercising my dogs (and indeed myself) I am now helping to chart the distribution and status of our birds. Along with many thousands of other birdwatchers I am participating in Bird Atlas 2007-11, a mammoth undertaking to map breeding and wintering bird populations within Britain and Ireland. The last time that this was done was nearly 20 years ago and much has changed since then. Buzzards have expanded their range to the east and are now breeding in Norfolk, making them a far more familiar sight in our skies than they were just a decade ago. Other species are known to be in decline and it is likely that we will see a contraction in the range that they occupy within the county, or a thinning in their numbers.

The project is being coordinated by the British Trust for Ornithology (BTO) and has two different components. First, a series of survey squares have been selected across the country and these will receive intensive survey visits from volunteer birdwatchers, twice in the winter and twice in the summer. I have taken on two of these squares, one where I walk my dogs and the other out near East Harling. Information from timed visits to these survey squares will be collated and then used to determine the abundance of different species across the country. We might find, for example, that Norfolk’s corn buntings are now concentrated in the fens or that our green woodpeckers are most abundant on the sandy soils of the brecks.

The second component has been termed ‘roving records’ and involves collecting simple records of birds from anywhere in the country. The song thrush or bullfinch that you see in your garden could prove to be an important record and can be submitted on a simple roving record form (available from Bird Atlas 2007-11, BTO, The Nunnery, Thetford, IP24 2PU). A record in winter of a fieldfare or a redwing will help the BTO to map winter distribution, while a summer record of a nesting long-tailed tit will reveal the breeding range. These roving records should be particularly useful for supplementing information from the more intensive, but time-restricted, counts made in the selected survey squares. Taken together they will supply the information needed by those addressing the conservation needs of our birds, providing an audit of bird populations and highlighting those species in need of additional conservation resources. So if, like me, you get out into the countryside (or a town or just watch the birds in your garden), why not get involved and make your contribution to Bird Atlas 2007-11.

Thursday, 15 November 2007

Mucking about with mammals


The other weekend I was fortunate enough to spend a very enjoyable morning with a group of mature students, teaching them how to find and identify mammals in the field. Much of the skill required to find and identify mammals actually centres on being able to locate and recognise mammal droppings and footprints – rather than the mammals themselves. This is because many of our mammals are elusive, avoiding contact with humans, and so are encountered only relatively infrequently. The signs they leave behind, however, can be found more readily and provide an ideal mechanism for establishing that a particular mammal has used the area. The students were all taking part in an evening course being run by the University of East Anglia. Each student was keen to develop his or her skills and to broaden their knowledge of our mammal fauna. Here, in Norfolk, we do fairly well for mammals and with a bit of effort you can encounter most of our terrestrial species – from the Chinese water deer that frequent the broads, through to the brown hares that do so well on our open arable farms.

When looking for signs of mammals you often spend a lot of your time bending over, crouching down or crawling about on your hands and knees. The grounds of Bayfield Hall, where Natural Surroundings is based, were our study area and, with the River Glaven flowing through the valley, we were soon able to find evidence of a range of mammals. Under the hazels were many of last years’ nuts, split open by squirrels. Adult grey squirrels split the nuts cleanly in two, but younger, inexperienced, individuals often make a bit of a mess and the opened shell is jagged and haphazard. Wood mice and bank voles, also partial to hazel nuts, open a smaller rounded hole in the shell, each with its own identifiable pattern of tooth marks.

Down by the river, on the areas of soft mud that we had smoothed over the previous evening, were the tracks of pheasants, brown rats and, in one spot, a passing stoat. These provided us with an opportunity to take casts of the tracks by using plaster of paris, something that I had not done since I was a child. This kind of hands-on detective work is great fun and it was clear that the students had enjoyed themselves. Of course, it has a more serious side as well, in that records of mammals (or evidence that they have used an area) have real conservation value. This is another important aspect of the course, teaching the students to collect and submit their records to the county biological records centre so they may be used more widely. 

Wednesday, 14 November 2007

Birds count cost of awful summer


It has been a poor summer for many of our breeding birds. The appalling weather that dominated from May through into July caused problems for nesting bitterns and lapwings, both caught out by rising water levels, and made life very difficult for nesting tits. It had all started so well, with the fine weather in April favouring early nesting species, like the long-tailed tits which had a bumper season. However, those birds nesting later in the year were caught out.

Species like blue tit and great tit time their nesting attempts to coincide with the annual peak in the abundance of caterpillars. They need to do this because each chick (and there may be up to 12 in a nest) requires something like 100 caterpillars per day. The arrival of heavy rain literally washed many caterpillars off the leaves, making food more difficult to locate for busy parents. Short on food, the growing chicks were also hampered by the fact that their parents were returning to the box wet. With far fewer body feathers than their parents, chicks quickly became damp and chilled and many a brood was reported dead in the nest.

Information from those with nest boxes in their garden made it apparent fairly early on that it was not going to be a good breeding season. These anecdotal reports have now been supported by the recently published results of systematic monitoring work carried out by the British Trust for Ornithology (BTO). Through the Constant Effort Scheme (CES), bird ringers working for the BTO collect vital information on movements, survival rates and productivity. Every summer, teams of CES ringers catch birds by using a system of special nets, with each net used in the same place and for the same length of time from one year to the next. This enables the researchers to look at the numbers of adult and juvenile birds that have been caught and, from this, establish a measure of breeding success. The 2007 breeding season has proved to be the worst on record for a number of species: blue tit productivity was down by half, that for great tit was down by a third and two migrant species (reed warbler and whitethroat) were down by a quarter. While a good breeding season next year may enable some birds to bounce back quite quickly, for others the poor summer is yet another thing that has gone against them. Some of the migrant species, like whitethroat, are facing problems on their wintering grounds in Africa and a poor breeding season here only serves to exacerbate their plight. We need to keep our fingers’ crossed for a better breeding season in 2008. 

Tuesday, 13 November 2007

November floods lure seabirds


Although the recent North Sea surge spared coastal communities, it did break through the sea defences near Salthouse, bringing flooding to the marshes west of Kelling. It was quite a sight to see this new expanse of water stretching away from the east bank at Cley. Sodden paths, now free from surface water, were covered with hundreds of worms, presumably killed by the saline conditions. A large pike lay dying on the edge of the one the drains and a tide-line of vegetation revealed the level achieved by the now subsiding waters.

This new waterscape appeared calm; sheltered from the northerly winds by the shingle bank, many waders and wildfowl took advantage of the new feeding opportunities. Small groups of brent geese, teal and wigeon, mixed with curlew, redshank and a solitary ruff. Many were feeding within feet of the coast road, providing good viewing for those brave enough to venture out under such threatening skies. One of the birds feeding in a newly formed roadside pool caught our eye as we followed the road east; a small pale grey and white wader, feeding in the water with a buoyant, almost clockwork, manner. This was a grey phalarope, a dainty bird which has been wonderfully misnamed. The species should be celebrated for the vibrant terracotta finery displayed during its short northerly breeding season and not the drab grey of its winter plumage.

The phalarope was picking tiny insects from the surface of the floodwater, moving forward and then rotating from side to side with the smooth transition of a mechanical toy on the top of a childhood music box. Each movement was so delicate that I found it hard to comprehend that this diminutive bird would spend the winter far out at sea, feeding in the waters off West Africa. That it was here, on the North Norfolk coast, was a result of the storms that had also pushed other seabirds close inshore. The phalarope would have been on its autumn migration, a very protracted affair given that the females may leave their breeding grounds in Iceland, Greenland and North America as early as mid-July. The males follow a few weeks later, once their dutiful role as single parent is complete. This was an adult, the plain grey back and wings showing no sign of the darker feathers that would signal a young bird. By now a crowd of birdwatchers had gathered to take in this aquatic ballet, the feeding phalarope occasionally rising into the air when spooked by other birds but always dropping back down into the same section of pool. The storms had provided it with a good feeding opportunity and given us a real treat.

Monday, 12 November 2007

Yuck, what is that stuff?


Most of the colours encountered in nature (at least here in Britain) are sombre and subdued. Rightly so, you may say, particularly when you think of a damp piece of woodland towards the end of a rather warm autumn. Those spots of bright colour, the hideous primary yellows and garish reds, are almost invariably pieces of litter, left by some mindless ruffian happy to despoil our beloved countryside. However, there have been times when my eye has been drawn to some almost luminous patch of colour which is natural in origin. These are the fruiting bodies of yellow slime moulds, crawling imperceptibly across the woodland floor.

Slime moulds can be pretty revolting to look at and, at times, seem almost alien in origin. Little studied, they have sometimes been classified alongside fungi, yet other authors have lumped them with the protozoa (simple single-celled organisms). However you view them, it is fair to say that these overlooked creatures are to be found just about everywhere on the planet (with some forms seemingly able to live submerged for several at a time). The part of their life cycle that we are most likely to encounter is the plasmodium; the slimy, almost jelly-like, stage which is mobile and gives rise to fruiting bodies; it is these fruiting bodies that are suggestive of a fungus. Most slime moulds produce a plasmodium that is just one or two centimetres across and able to travel up to 10 centimetres a day. Some of the largest ones can reach two metres in diameter and may weigh over a kilogram. Alan Feest, quite a fan of slime moulds, once related how he had stumbled across a large slime mould, draped over a tree stump and giving the appearance of somebody having tipped a can of whitewash over the stump. When he returned the next day, the slime mould had moved off part of the stump and onto a neighbouring bramble, leaving a trail of slime behind!

Fruiting slime moulds produce spores which, catching the wind, disperse over large distances. The spores are remarkably robust and may survive for many decades before ‘germinating’ or ‘hatching’ (I am not sure which is the more appropriate term) into a simple single-celled stage. This feeds on bacteria and grows, developing thread-like appendages in wet conditions (these help it to move around) but retreating into a cyst when it becomes too dry. At some point the unicellular stage develops into a plasmodium, creeps about and then fruits. This complex life-cycle, and the fact that these are organisms that blur the line between animals and fungi, make slime moulds rather special and, most probably, worthy of our attention, despite their odd appearance.

Saturday, 20 October 2007

An eye for detail


Regular readers of this column will know of my great passion for experiencing the natural world first hand; getting out into the countryside and immersing yourself in the world around you. Of course, it is not always possible to do this and, with so much countryside out there, even those of us who spend a lot of time out of doors cannot experience everything. That is why nature writing, wildlife filmmaking, sound recording and art (in all its forms) can offer us the experiences of the natural world one step removed. In some cases, the countryside and the wildlife it contains are captured in a way that simply relates their true form; in other instances, the picture we see has been interpreted by the writer or artist and they have left an echo of themselves on the object that we ultimately view.

I have a huge amount of respect for those who can deliver views of the natural world that most of us do not have the time, patience or opportunities to witness. As such, I enjoy seeing a painting or photograph that captures an inspiring piece of wildlife action, or reading a piece of prose that adds to my sense of wonderment at the depth of beauty that exists within the natural world. There are photographers whose work captures the interplay between wildlife and the Norfolk landscape so completely that I am deeply moved by what I have seen. One of these is Chris Gomersall, a photographer whose impressive portfolio of work has graced many books and magazines. His photograph of a rook, which appears in Birds Britannica, shows the bird levering a bin bag from a dustbin; the crisp and striking image bubbles over with the mischievous resourcefulness of this bird and serves to illustrate an important piece of behaviour. At the same time, other images captured by Chris show barn owls and pink-footed geese silhouetted against soft-toned Norfolk skies, evoking memories of my own trips to Norfolk’s north coast. Such images blur the line between straight photography and art. They have an integral beauty of their own, derived not from the subject matter but from how it is portrayed. One particular image of Chris’s stands out for me and, perhaps surprisingly, it is not a bird but a simple portrait of a wood blewit mushroom, its rich purple tones set off beautifully by the ochres and browns of the dead leaves that carpet the ground around it. For those interested, Chris Gomersall has an exhibition of his work running at Brancaster Staithe Village Hall from 26th-28th October and I, for one, will be dropping in to share his experiences of Norfolk’s wildlife.

Friday, 19 October 2007

A new sound in the forest


There is a new sound in the half-light of early morning, a deep intonation that carries well across the otherwise silent forest. This is the roar of a red deer stag, one of at least three on my local patch who are taking part in the annual rut – a seasonal proclamation of ownership of a harem of females. Although typically described as a roar this challenge to other stags recalls the deep bellow of a bull. Unlike their upland cousins these sylvan red deer usually utter a single resonant groan, with long intervals in between each roar. It is an unsettling sound in the half-light, an echo of a time when the woods of Britain were truly wild and inhabited by a range of large mammals now extinct.

The seasonal cycle of sexual activity in red deer is primarily driven by changes in photoperiod (the daily pattern of light and darkness) but it can also be influenced by the condition of the stag. Rutting is a draining experience and a stag may lose up to a fifth of his body weight, predominantly because of his greatly reduced intake of food during the rut. Beginning in late September, the rut itself is initiated by the largest and oldest stags who seek out traditional sites. Male red deer tend not to hold harems of females until they reach five or six years of age but they may find it easier to establish a harem in woodland than on the more open uplands of Britain, where red deer densities can be much greater.

As with many other animals, the act of attracting a mate (or mates in this instance) has become a highly ritualised process. During the rut a stag will not only roar but will also thrash the vegetation, wallow and adorn himself with his own urine. In high density populations, individuals of comparable rank and size may end up fighting. After a roaring contest, the closely matched males may walk side by side, each presenting their bulk to his opponent. Then one individual will lower and turn his antlers, interlocking them with those of his rival. A pushing and twisting contest then follows which, not uncommonly, results in serious injury or even death. The prize in all this display and aggression is access to one or more females and the opportunity to secure parentage of the next generation. While woodland red deer tend to have small harems, with seven or eight hinds in attendance, those on the open uplands will typically hold more females. The rut will continue for several weeks, ending sometime in November. Until then, my morning walks will be blessed by this new soundscape, the roaring of stags.

Thursday, 18 October 2007

The winter geese arrive


The first of the winter’s geese have arrived, the end of a journey that has brought them south from breeding grounds in eastern Greenland and Iceland. These are the pink-footed geese, harbingers of the approaching winter, and a welcome addition to the soundscape of bleak November and December days. They are our very own spectacle, vast flocks that fill the early morning sky as they set out from overnight roost sites to feeding grounds scattered along the North Norfolk coast. Changes in hunting pressure and wintering grounds have led to an eight-fold increase in the numbers wintering here since 1950 and there are now some 250,000 using Britain between September and the end of April. This represents over 85% of the total world population, making Britain an incredibly important place for these birds.

Historically, the pink-feet would have wintered on saltmarsh, feeding on the mixed grass and short herb swards, but over the last century there has been an increasing tendency to feed on arable land, particularly on sugar beet, waste potatoes and barley stubble. Such opportunities last through into February, when the fields are ploughed, and then the geese move on to utilise pasture. Their numbers are monitored through the Wetland Bird Survey (WeBS), coordinated by researchers based at the British Trust for Ornithology. Vast flocks can be difficult to count and an expert eye is needed to work out the numbers of birds present.

Other geese species may be seen feeding alongside the pink-feet, including rare visitors from further afield. The breeding grounds used by the pink-feet overlap with those of other species and, on occasion, birds may migrate with the wrong group, ending up many thousands of miles from where they should have spent the winter. This year, for example, a snow goose, which normally breeds from Arctic North America to north-west Greenland and winters south to Mexico, was tracked down the east coast, arriving with the pink-feet in Norfolk at the end of September. This may well be a genuine vagrant but there is also the possibility that the bird belongs to the small feral population that has arisen due to individuals escaping from private collections here in Britain. That genuine snow geese do reach Europe has been demonstrated by bird ringing, with an individual ringed in Manitoba turning up in the Netherlands three years later. Another unusual visitor to Norfolk has been the lesser Canada goose, one of which spent the 2005/06 winter in the company of pink-footed geese at Holkham. This species breeds in northeast Canada and is noticeably smaller than the naturalised British Canada geese. While these vagrants excite twitchers it is the scale of the pink-feet flocks that enthral more casual birdwatchers.

Wednesday, 17 October 2007

Jays on the move


There appears to be a definite shortage of acorns this autumn, something that is not just restricted to the county of Norfolk and which is already having an effect on some of our bird species. Most notable among these is the jay, one of our most resplendent birds and so beautifully described by Mark Cocker and Richard Mabey in Birds Britannica. With its “… electric blue patch on the pied wings and a body colour of warm greyish-pink, set off by bold moustaches, black crown freckles and a striking white rump” this is a stunning, though secretive bird. Such is the beauty of the blue wing feathers that jays were targeted by milliners, the feathers often gracing the hats of well-to-do ladies.

Over recent days I have seen or heard any number of jays, and many of these have been in open country which suggests that they are having to work hard to find the acorns that they favour. The acorn crop would normally form a key part of the diet for many months, with individual jays caching some 5,000 or so acorns in a normal year. The bird will collect three or four acorns in one go, transporting them to favoured locations to be stored in natural cavities or in damp ground. Amazingly, the jay is able to memorize the locations of most of the buried acorns, with those missed contributing to the regeneration and spread of oak woodland. A shortage of acorns in one area will prompt the jays to move elsewhere and this leads to periodic irruptions, with individuals from some northerly populations moving en masse into south-eastern Britain or the near Continent. Although one of the largest movements took place in the autumn of 1964, when 35,000 birds were counted moving over Gdansk in a four-week period, other significant irruptions have taken place more recently. For example, some 173 were noted passing Titchwell in October 1983 and smaller numbers have been noted arriving in off the North Sea since then.

A lack of other tree seeds, most notably beech mast and conifer seed, may well signal the arrival of greater than usual numbers of other bird species, including brambling, chaffinch and siskin. This is likely to lead to busier than usual bird tables and those monitoring garden bird populations are predicting a good winter for garden birdwatchers. No doubt, some of our rural gardens will be visited by jays, arriving early in the morning to feed on peanuts, bread and other scraps. Although not welcomed by everyone – jays are still controlled on many game estates – they are great fun to watch, full of character and brimming with a mischievous intelligence.

Tuesday, 16 October 2007

Toadstalls


To me, autumn is the season of decay; much of the luxuriant growth of summer is broken down and utilised by a host of unseen organisms. Included with these are the fungi, hidden for much of the year and only now evident as their fruiting bodies push up through the ground. Perhaps the most well-known of the autumn-fruiting fungi is the fly agaric, it’s red cap – speckled with white – instantly recognisable to even the most casual of observers. This is the toadstool upon which gnomes are pictured, which is featured dancing by Disney and which has a folklore extending back into the antiquity of many cultures.

The fly agaric belongs to a genus of fungi known as the Amanita, which contains not only some of the most beautiful fungi but also some of the most deadly. The Amanita are cosmopolitan in distribution and the 30 or so examples in Britain include species that are also found on the sun-bleached hillsides of North Africa and the Arctic tundra of Alaska. The various species typically form close relationships with trees and all of the British species are thought to be mycorrhizal. This means that instead of occurring loosely in the soil, their underground structures (known as hyphal threads) accumulate around tree roots. Some of the threads penetrate the roots and help the fungus to receive moisture and nutrients from the tree; in return, the tree gains an enhanced ability to compete with other plants for soil nutrients. These relationships are complex and this may be why fly agaric is usually found associated with birch and, to a lesser extent, pine, rather than other tree species.

The name ‘fly agaric’ comes from the formerly widespread practice of using the fungus as an insecticide. The chopped fungus would be sprinkled with sugar or placed in milk, killing the flies that it attracted. The main toxic ingredient in fly agaric is concentrated in the red skin of the cap but with ageing, permeates into the cap itself. The toxin attacks the central nervous system causing lethargy and nausea and, depending upon the dose, a hallucinogenic high. As such, fly agaric was regularly used to induce a state of spiritual exaltation in primitive cultures. Needless to say, messing around with such potentially dangerous toxins is not to be recommended, particularly when this group of fungi contains species that can kill. The aptly named death cap has been responsible for 93% of the European deaths caused by fungus poisoning; just half a cap is sufficient to bring about death. Strangely, several members of the genus are edible after cooking but, given the potential costs of a misidentification, I don’t think I will be trying them.

Monday, 15 October 2007

A nightly gathering


The other afternoon, on my way to give an evening lecture, I made a brief stop at Waitrose in Swaffham. The crisp, clear day was coming to an end, as the sun slowly slipped towards the horizon, dipping behind the cathedral-like spire of the wind turbine that now dominates the local landscape. From all around me I could hear the loud ‘chis ick’ flight calls of pied wagtails, as individual birds moved between the young trees that dotted the car park. Others stood, silhouetted against the sky on the roof of the supermarket, marking the beginnings of a gathering that would, most likely, be repeated each night throughout the coming winter.

Pied wagtails are well known for their communal roosting behaviour, perhaps because such roosts are often formed on or around man-made structures. These small, insect-eating, birds can find winter a difficult time; food is scarce and energy expenditure is high. In the short-days of mid-winter they may spend 90% of the daylight hours feeding, collecting a prey item every four or five seconds. Even this high rate of feeding is only just enough to balance their energy expenditure. In particularly cold winters, many individuals will move further south, deserting southern and central Britain, to winter in France and Spain. Even so, winter mortality can be very high.

It should be no surprise then, that pied wagtails gather to roost communally, seeking out the warmest sites. These include factories, hospitals, commercial glasshouses and trees along major roads or in supermarket car parks. Not only do such roosting sites provide much-needed warmth, they can also act as information centres. Birds that have not fed that well during the day are able to spot individuals that have been more successful; the following morning they will follow these individuals out of the roost and, with luck, have a better day. One final benefit of roosting communally is safety in numbers. While the presence of many small birds at a roost might attract predators, the individual’s chances of being taken by a predator remain lower than they would be if the bird were alone.

Most pied wagtail roosts within Norfolk number just a few tens of birds but roosts in excess of a hundred strong are not uncommon and a small number have been known to hold over 1,000 birds. For example, a roost in Brigg Street, Norwich, was reported to have held 2,213 individuals on the night of 12 January 2001. Pied wagtail roosts lack the frenetic energy of starling roosts and, because of the choice of roosting site, are often more readily viewed. Next time you are out shopping late afternoon keep an eye out for these delightful little birds.

Saturday, 22 September 2007

Take time to watch the little things


The other afternoon I took a break from tiling the kitchen floor to make the most of the now weakening late summer sun. Sitting on the wooden bench in our garden I was able to spend some time watching various insects going about their business. Large numbers of harlequin ladybirds, at various stages of development, could be seen on the fence, the pot plants and on the large buddleia that drapes over from the garden next door. The harlequins have obviously had a good season, their numbers are well up on last year and I fear that it won’t be long before some of these unwelcome aliens seek shelter in the house. Not only are they known to bite but they also stain upholstery and can gather in very large numbers around windows!

My attention was caught, however, not by the ladybirds but by the behaviour of a wasp. Flying along the fence, just below the top, I thought that it was about to become ensnared in one of the many spiders’ webs that litter the fence panels. Instead of becoming the victim, the wasp began to act as if it was actively seeking out the owners of the webs. Passing by one particular web, the wasp suddenly veered towards its centre, where a tiny piece of brown leaf hung like a spider. The wasp seemed to hover just off the leaf as if trying to work out if this was a spider or some other object. Its curiosity satisfied, the wasp moved off. It was then that I noticed that the wasp was quite deliberately quartering the fence panel, actively checking out each web in turn. This gave me the very definite impression that the wasp was hunting. This is something that I have not witnessed before, nor read about in the literature. Wasps feed on a range of foodstuffs, including other insects, and so perhaps I should not be surprised to see one hunting in this fashion.

Seeing this wasp, and being able to observe an element of its behaviour, made me appreciate just how much interesting life there is within my own, very ordinary, garden. There is something about watching insects that is special. Perhaps it is because they are so small and that you have to watch very carefully to see what they are actually doing. Watching carefully means that you are putting more effort into your observations and, consequently, getting a more rewarding experience from them. Of course, you can apply the same level of detail to watching larger organisms, like birds, but this often seems unnecessary and you can end up rather taking them for granted. Perhaps this is why insects are so fascinating.

Friday, 21 September 2007

Good news for garden birds


There has been some good news for garden birds of late; news that has, to some extent, slipped by unnoticed because attention has been focussed on more glamorous species. This is the addition of several garden birds, most notably dunnock, starling and house sparrow, to the Government’s list of species to receive priority conservation action. Known as the BAP list, where BAP stands for Biodiversity Action Plan, the list is one of a number of different tools that the Government uses to help it determine the best ways in which to deliver its conservation action within the UK. Periodic reviews of the status of each of our plants, animals and habitats, enable experts to assess which species are in greatest need of support. Central to this review process are the data collected through long-term monitoring schemes, each charting the changing fortunes of our wildlife.

Some 26 bird species were already on the list (following the first BAP review, carried out in 1995) and to these have been added a further 33. The inclusion of house sparrow and starling is particularly welcome; house sparrow numbers have declined dramatically over recent decades and our breeding population is now less than half what it was back in the 1970s. A similarly alarming decline has hit both our breeding and wintering populations of starling. That two species, so closely associated with Man, should be in such difficulties gives us fair warning of our impact on the environment around us. The reasons for their declines are not fully understood and their inclusion on the BAP list should help to direct more resources towards identifying the underlying causes. Once these have been identified, conservationists can set about trying to halt and, ultimately, reverse the declines.

A number of other species that frequent gardens were already on the original BAP list and it is interesting to see how being on the list has helped their status. In some cases, such as for song thrush, inclusion on the BAP list has prompted a great deal of research and this has seen a recovery in numbers in recent years – evidence that the system works. However, for certain other species more clearly needs to be done. The decline in bullfinch has continued, despite inclusion, but we now have a much clearer understanding of why the species is having such a tough time. One of the most important aspects of inclusion on the list is the establishment of a number of key targets. By using targets, it is possible to determine whether the resulting conservation action has been successful. It also provides a focus for the researchers, something to aim for and something by which they can measure their success.

Thursday, 20 September 2007

The antics of young crows


I never tire of watching the antics of young birds and over the past few weeks have been delighted by the presence of a family party of crows. Although overlooked by many, and persecuted by others, the carrion crow (to give the bird its full name) is a resourceful, emblematic and adaptable bird, with a wide range that stretches from Ireland and Portugal in the west to China in the east.

Our local pair, nesting high in a tree on the edge of a narrow finger of woodland, has three youngsters. Over past weeks the parent birds followed a tireless routine of bringing food to the nest and seeing off potential predators. Now their role has changed; their young charges mobile and keen to explore the expanding world around them. The impression they give off is one of precocious teenagers, trying out new things and then running to mum went it all goes wrong. The parents seem resigned to the demands forced upon them but remain vigilant to potential threats. New objects attract particular attention, as one of my colleagues noted the other day. He watched one of the young crows investigating a hedgehog. Each time the crow approached, the hedgehog rolled into a ball and remained still. The crow seemed puzzled, then lost interest; the hedgehog unrolled itself and started to go about its business again. Now moving, the hedgehog attracted the crow’s attention and the game of stop/start repeated itself. Although this inquisitive behaviour may sometimes land the crow in trouble, it is an important component of learning, preparing the young bird for adulthood and helping to make the species so successful.

It can sometimes be difficult to distinguish between crows and rooks, since both share the general impression of a large black bird. There is an old country saying which runs “if tha’s a rook ‘tis a crow and if thems crows tis rooks.” This alludes to the different social systems of the two species, with the highly social and colonial nesting rook likely to be seen in large groups. Carrion crows, on the other hand, are typically seen singly or, as at this time of the year, in small family parties. There are structural differences too; carrion crow has a heavy black bill, which appears more blunt at its tip than that of the rook. The rook has a steeper forehead, a bill that tapers along its entire length and shaggy feathering on its thighs. Over the coming weeks both birds may come together, as they collect in huge winter roosts which draw in birds from large parts of the region, a feature so beautifully described by the author Mark Cocker in his new book ‘Crow Country’.

Wednesday, 19 September 2007

Bats make the most of late summer insects


Our local bats seem to have been busy of late. Each evening, just as dusk starts to settle over the town, two or sometimes three bats can be seen, each silhouetted against the last of evening’s light. There are two species that make use of our garden, something confirmed through chance encounters with individuals perched on walls or, in one case, caught in a mist net set for roosting thrushes. By far the commoner species is one of the pipistrelles, most likely the soprano pipistrelle. Up until just a few years ago it was thought that there was just one species of pipistrelle in Britain, then it was discovered that this one species was in fact two. One of these, the pygmy pipistrelle, tends to occur in smaller colonies in more rural areas, while the other, the soprano pipistrelle, forms larger colonies and often roosts in houses. In 2001, a third species, Nathusius’ pipistrelle, was found apparently breeding in east Norfolk. It’s presence was revealed by Susan Parsons who had picked up the species’ social calls on a bat detector used to monitor the colony of barbastelle bats at Paston Barns.

The other species using my garden is the brown long-eared bat, a highly distinctive species within the county; its close relative, the grey long-eared bat, is restricted to a small area in the extreme south of England. As their name suggests, long-eared bats can be distinguished from all other British species by their enormous ears, which are joined at their inner bases. These ears are used by the bat to pick up “reflections” which bounce back from objects caught in the bat’s weak echolocation pulses. Brown long-eared bats are leaf gleaners, typically hunting in lightly wooded areas and taking moths and other insects from the surface of leaves. The tall sycamore in our neighbour’s garden appears to form part of the hunting beat used by one or more of these bats, and they can be seeing making relatively slow passes around the tree. The flight of the local pipistrelles has a more frantic feel about it.

I have encountered brown long-eared bats on and off over the years. The species had both a breeding colony, some 40 to 60 strong, and a winter hibernaculum at Wolterton Hall in north Norfolk, where I used to live. In the summer moths, the breeding females and their young occupied the attic space above the old stable block, while in winter they were to be found in the cellars under the hall – where temperatures were buffered against outside ambient fluctuations. Nowadays, I only tend to see one close-up when it perches on the sheltered wall of my side passage to dismember a moth. 

Tuesday, 18 September 2007

Dark bush Crickets


There was a stillness to the morning, a calm that had draped itself over the river, delivering an almost soporific quality to the air. The river flowed with a gentle ease, reflecting the lack of rain over recent days, as it murmured its way quietly downstream. Only the steady chirps of dark bush crickets broke the silence. These calls, with their resonant quality, had a tropical feel to them, something enhanced by the slightly humid air of this mild early morning. Every bush or piece of waterside vegetation seemed to host several crickets; each one was sat squarely like a little toad, squat in posture and dark brown in colouration. The short chirping call was an advertisement, directed at a potential mate.

I had come down through the meadows to collect two crayfish traps, set the previous evening. As I moved through the vegetation I could smell the umbellifers and that strange aroma that I have come to associate with wet meadows. It is an almost acrid scent, slightly unpleasant and vaguely reminiscent of a public lavatory, but with an underlying sweetness. I remember how the short-tailed voles, that I used to live-trap as part of a study into their ecology, also had this scent and how it clung to my clothes after early morning rounds of my traps. Did the voles acquire the scent through their diet or because they lived within the pungent vegetation? I am sure a botanist could tell me its source and the chemical nature behind it.

The two traps are packed with crayfish, despite being in the water for only a dozen hours, and it is clear that this section of the river still supports a very large population of signal crayfish. I have commented before upon the problems that this introduced species has caused, wrecking river banks, reducing fish populations and eliminating our own native species of crayfish. Although I am trapping these signal crayfish in order to monitor their numbers, and to test the effectiveness of different types of trap, I am not allowed to release them back into the river. Instead, they must be killed and so end up in a pot, cooked and then served with a garlic mayonnaise or forming the centrepiece of a pasta dish.

As I trudge back to the car with my bucket of crayfish, I become aware of another cricket calling. This is Roesel’s bush cricket, a large species with a distinctive high-pitched call. It sounds like a softly running fishing reel, of the old-fashioned style used for fly-fishing, and is one of the first sounds to disappear through the hearing loss than comes with age. I am glad that it is still part of my morning soundscape.

Monday, 17 September 2007

A hissing beetle


I was surprised and, to tell the truth, a little unnerved by the loud hissing sound generated by the small black beetle that I had just picked up. It was as if there was some kind of deep-rooted instinct to pull back from any creature that hisses at you; some evolutionary impulse, derived from ancestors exposed to the harsh realities of living alongside more dangerous animals than this small beetle. I knew what the beetle was, knew that it was harmless and yet I felt a momentary flash of fear. Why was this? That such a reaction was provoked, despite my knowledge of this beetle, might seem to suggest that this irrational response is inherited and not simply a behaviour learnt during childhood – nature winning out over nurture. However, things are not as clear-cut as this. Experiments using young, wild-born monkeys suggest that a fear of snakes is learned by watching how other group and family members react. A monkey that is shown a video of another monkey reacting to a snake, learns to fear snakes itself but, manipulate the video to replace the snake used in the experiment with a flower and a na├»ve monkey (that has never seen a flower) does not suddenly learn to fear flowers. This, and similar experiments, demonstrate that monkeys learn to fear some objects (e.g. snakes, spiders and water) more readily than they learn to fear other, typically less threatening, objects. So, there may well be a genetic influence at work here as well.

The beetle in question goes by the name of Cychrus caraboides – it has no English name and specialises in feeding upon snails. The hissing sound, subtle though it is, is presumably a measure deployed to warn off potential predators. A similar approach is adopted by a wide range of other insects and, indeed, by a number of vertebrates. Great tits, for example, will hiss if disturbed on their nest and it has been suggested that these birds, and a number of other cavity-nesting species, hiss to give the impression to a potential predator that there is a snake in the cavity and not just a defenceless feathered meal. In other species, notably snakes, the hissing is a warning which is backed up by a venomous bite. Because of this, and because of the underlying threat implied by the act of hissing, other, harmless, creatures have been able to use hissing as a form of deception – making out that they are dangerous when in fact they are not. Although I had nothing to fear from this beetle, I must admit to holding on to it for a rather shorter time than I would otherwise have done!

Saturday, 25 August 2007

Disease may benefit nesting birds


A walk through Thetford Forest gives the impression that you are in a huge monoculture; the ranks of immense, silver-grey trunked conifers stretch away into their dark, unwelcoming distance.  Yet there is some sort of diversity here. Where the stands of conifers run alongside a road there is a thin veneer of deciduous trees, oak and beech, planted perhaps to give passers-by the impression that the woodland is natural. Within the acres of plantation woodland itself, there are stands of different age, collectively providing a varied micro-habitat for birds, animals and plants. While the younger-aged stands support important species, like nightjar and woodlark, mature stands provide nesting sites for crows, long-eared owl and goshawk. There is even some degree of diversity to the types of conifers that have been planted and this can also have an effect on which bird and animal species are present.

Two of the most significant pines in the forest are the Scot’s pine, which has not been a native in England for some 4,000 years, and the Corsican pine, a species that is commonly planted on dry, sandy soils across southern England. The Scot’s pine is a familiar part of the Breckland landscape, its twisted forms often present in the exposed hedgerows and shelterbelts. Many of these were planted during the enclosures of the 19th Century, as they were thought to be a better choice on such light soils than the more traditional hazel or hawthorn.

If you were to map the distribution of crow and bird of prey nests within the forest, you would most likely see a preference for nesting in Scot’s pine over Corsican. This is because of the different shape of the two trees, that of the Scot’s pine being better suited for supporting the nests of crows. Crows prefer to nest slightly down from the top of the tree, generally on a strong limb or in a stout fork against the trunk. Since a new nest is built each year, the old nests become available for those birds of prey, like hobby, that tend not to make their own nest. Over the next few years we will see a change in the types of conifers being planted within the forest. This follows an outbreak of red band needle blight disease. In Britain, the disease is caused by a fungus called Dothistroma septosporum, which has hit Corsican pines across a wide area. A moratorium on the planting of Corsican pine will be in place for at least the next five years, while research into the disease is carried out. Consequently, we are likely to see more Scot’s pine, larch and sitka spruce being planted, which should benefit future generations of crows.

Friday, 24 August 2007

Musical crickets


August is a good month in which to look for crickets and grasshoppers. After hatching earlier in the year, many species will by now have passed through a succession of nymphal instars to reach adulthood. From the rank grass outside the entrance to work, the drawn-out, high-pitched songs of male roesel’s bush crickets mix with shorter bursts from field grasshoppers. These bursts of noise are invariably the result of stridulation – the rubbing of one body part against another to make a sound. In the case of the bush crickets, modified forewings are used to produce the sound, which is then amplified by a further modification of the wing. In grasshoppers, the sound is produced by modifications to the hind legs – namely a series of stridulating pegs – which are rubbed against the most prominent veins of the flexed forewings. Some observers refer to the songs as ‘chirps’ but this can be somewhat misleading. Strictly speaking, each song is comprised of a number of syllables, with each syllable representing one complete upstroke and one complete downstroke (think of a violinist). A series of these syllables may be strung together and are then referred to as an ‘echeme’. Hence, a field grasshopper will produce an echeme of 9 syllables length, lasting some 0.2 of a second. Interestingly, the oak bush cricket lacks the wing modifications seen in its relatives and so does not stridulate. Instead it produces a drumming sound by tapping its hind legs against whatever it happens to be perched upon.

The oak bush cricket is rather unusual in two other respects; it is the only British cricket to be almost entirely carnivorous, feeding on a wide range of other insect species, and it is our only completely arboreal species. Oak bush crickets are sometimes attracted to light and the species may be found indoors or even appear in moth traps. This may explain why this small bush cricket is so often encountered across the southern section of Britain.

Another cricket that has been much in evidence in recent days is the speckled bush cricket. This is a larger beast, reaching up to nearly two centimetres in length, which can be found in its adult form from August through into November. A large female, with her beautiful, scimitar shaped ovipositor, was on our grape vine the other day; a pale green colour – with tiny dark spots – she was difficult to pick out on the leaves, reinforcing her unobtrusive nature. Despite her larger size, she is largely vegetarian in habits; a trait which could have explained the damage to the vine that had appeared within the last week. Still, I would happily tolerate this, knowing that such a fine insect was in residence.

Thursday, 23 August 2007

Birdwatchers flock to Bird Fair


One of the beauties of birdwatching is that it can be either a solitary or sociable hobby, depending upon the mood that takes you. There are times when I seek out the attachment with nature that comes from birdwatching alone on my local patch or on one of the quieter stretches along the Norfolk coast. I can watch a bird, undisturbed by the comments of others, and really appreciate its character. At other times, I enjoy the comradeship and happy banter that is derived from the company of other birders, seeking out some rarity or combining a spot of birdwatching with a pub lunch or cake-filled visit to a tearoom.

The social side of birdwatching was brought home to me over the weekend, while working at the British BirdWatching Fair, held annually at Rutland Water. This event, the biggest of its kind in Britain (and quite probably Europe), brings together birdwatchers from across the continent. Many come to feast on the multitude of stands selling and promoting everything from binoculars and books, to birdwatching holidays and bird conservation. Others delight in the opportunity to listen to talks or to question ornithological experts on bird identification and behaviour. It is also a place to meet old friends, many of whom I only see at the bird fair, and to make the acquaintance of others who, like me, delight in watching and studying birds and other wildlife.

There is always a real buzz about the place and most visitors must come away from the fair pumped full of enthusiasm for their hobby. For me, in my role as the organiser of the BTO/CJ Garden BirdWatch, it is meeting those who participate in my survey that most inspires me. They are a diverse crowd; a mix of armchair birdwatchers – who only occasionally venture out to watch birds on nature reserves, keen birders – who dash around the country in search of rarities, and those in between, all watching birds to va rying degrees. There is one commonality though; all of these people enthuse about their garden birds. They delight in relating stories of chance encounters or in detailing observations on unusual bird behaviour that they have witnessed in their garden. Most of these garden birdwatchers get as much from witnessing the commonplace – the blackbirds, robins and finches – as they do from seeing something more unusual. To me, this emphasises the tremendous appeal of birds and of birdwatching itself. It is a hobby that is accessible to anyone and this must be why it draws in such a diverse following of acolytes. You can pick your own level, involve yourself as little or as much as you choose and that has to be a good thing.

Wednesday, 22 August 2007

Transition


There has been a noticeable chill in the air over recent mornings, the overnight drop in temperature sufficient to cast a heavy dew. The tall vegetation that flanks the forest rides hangs seed heads bowed by the weight of the dew upon them and tiny droplets of water glisten in the first of the sun’s rays. The gossamer of a thousand spiders is draped over the vegetation like the silken threads of an untidy seamstress. Here and there a whole web, radiating out to points of firm anchorage, is stretched and contorted, pulled down by the weight of dew that coats its every thread.

Is autumn upon us? It seems too early, yet there are the tell-tale signs that summer is moving towards its end. The screaming parties of swifts have left, deserting the rows of terraced housing and those few that remain have fallen silent as they make their lonely arcs across the sky. Small numbers of house martins are beginning to drift southward and swallows will soon be gathering on the overhead wires. The woods hold a scent of fungi, their fruiting bodies erupting through the surface to fling their tiny spores onto the strengthening winds. Reports of sandpipers and whimbrel herald the arrival of the first autumn passage migrants; with breeding finished they are free to move south.

I welcome this slow change, the steady transition between seasons, as nature turns through another part of her annual cycle. The lush, verdant growth of early summer is being replaced by mature browns as plants begin to shift their resources, either drawing back within themselves to fuel the spurt of growth that will come next year, or packing seeds that will soon be dispersed by a procession of unwitting accomplices. This process of renewal fascinates me; I like the idea of drawing back within myself as the months of light and warmth pass, hoarding those experiences gathered throughout spring and summer in readiness for the winter ahead. By doing so I hope to remain in touch with the ebb and flow of the seasons, accepting the pattern of the natural world around me and not blinkered to the narrow view, offered by a world in which we can divorce ourselves from the seasons through artificial lights and gas-fired central heating.

This is why these first crisp mornings that hint at autumn are so invigorating. My senses are alert to the changes in temperature and light, to the scents and behaviour of plants and animals and I feel closer to the world around me. In some subtle way we are all influenced by the changing of the seasons; we should acknowledge this and celebrate these periods of transition, as one season passes into another.

Tuesday, 21 August 2007

Chalk-hill Blues benefit from careful management


As I head southwest down the A11 and onto the A505 so I leave the acidic, sandy Breckland soils behind and cross onto the underlying chalk. Much of the chalk grassland has been lost to agriculture and the remnants are restricted to the steeper slopes of the chalk escarpment and to areas of favourable land-use, such as horseracing and golf. I am heading to the chalk grassland to search out the chalkhill blue, a butterfly that is on the wing in August. Instead of stopping near Newmarket to view colonies on the Devil’s Dyke and Fleam Dyke, I am travelling further afield to a colony on Therfield Heath, just to the west of Royston. My reason for visiting this particular colony lies in its history; Therfield famously attracted butterfly collectors from across Britain, each drawn by the lure of the varied colour forms of the butterfly to be found on the heath. Most of our butterflies are known to exhibit unusual colour forms from time to time, known as aberrations, but the chalkhill blue is noted for having more forms than is typical. The large population at Therfield Heath numbered many thousands and early last century the heath would have been inundated with collectors, each seeking that elusive aberration to add to their collection. One particular aberration, known as semi-syngrapha, in which the normally brown-coloured female has blue wings typical of the male, was the main target of the collectors.

Sadly, the pressure of collecting, coupled with changes in land management – notably the cessation of grazing by sheep, resulted in a dramatic decline in numbers and the population of chalkhill blues fell to dangerously low levels. These were restricted to the tiny pockets of suitable chalk grassland that remained, some only a few square metres in size. Fortunately, thanks to the efforts of local volunteers with an interest in the butterfly, the population was saved from extinction and since 1989 the number of chalkhill blues has increased. I wanted to see the results of this work and pay homage to the volunteers’ efforts by visiting the heath to photograph the butterfly.

One unusual aspect of the heath is the presence of a golf course, many fairways and greens of which are perched precipitously on the chalk escarpment. It is a large site and I thought that it might prove difficult to locate the discrete colonies. However, it did not take long to find the blues, the males actively quartering the vegetation in search of females that remained hidden below. These were delightful butterflies and seeing a dozen together made me wonder how it must have been to witness hundreds on the wing when the population was at its peak