Wednesday, 29 February 2012

A bright start to spring


On these bright, late February mornings, there is a real sense that spring is in the air. No longer is it just the wistful tones of the Robins that punctuate the still chill air. Instead, other songsters have joined the chorus: the ‘thrice-repeated’ notes of Song Thrush, the ‘teacher-teacher’ of Great Tit and the rich warbling song of Blackbird have been added over recent weeks. Just last week it was the ‘little bit of bread and no cheese’ song of Yellowhammer that was added to my morning walks through the mixed-age plantations.

Yellowhammers seem to do well in the younger-aged compartments of conifers, making the most of the snag lines of old stumps that run in parallel lines across the recently replanted blocks. Throughout the spring and early summer months, their delightful song can be heard and individual birds can be watched back to neat nests tucked within the grassy cover that sits alongside the snag lines.

For me, as a child, the Yellowhammer was a farmland bird inhabiting the richer hedgerows of the Sussex borderlands. It was a similar story when I first arrived in Norfolk; living in the north of the county it was the winter flocks on game cover that I most remember. However, when I moved to the Brecks the Yellowhammer became a bird of the forest, favouring the open areas of clearfell for breeding and then moving onto the surrounding farmland in winter, where we might catch them in our nets, set for licensed bird ringing.

The Yellowhammer is a bunting, its robust bill an indication of its preference for larger seeds and grains, much like its relative the Reed Bunting. During the breeding season, however, insects and other invertebrates dominate the diet. Birds can be spotted feeding on open ground and then watched back to their nests. The nest itself often has a ‘doorstep’, a little gathering of material that protrudes at the front of the nest. Tucked within the nest cup will be the eggs, an off-white colour often tinged with purple, onto which are finely-scribbled purple-brown or black markings. The first eggs are likely to be laid during April, so the breeding season proper is still a little way off but it will run for several months, the birds attempting two or even three broods during this period.

At this time of the year I like to get my bearings on where territories are being established. Because I have a regular ‘beat’ I can soon work out where to focus my nest recording efforts later in the season. The work done now will make the task of finding and monitoring nests that much easier come the busy spring months.

Tuesday, 28 February 2012

Arachnaphobes look away now


I spent part of the weekend taking down an old shed that had reached the stage where new repairs would be pointless, the main structure rotten and unstable. As well as the pale shoots of ivy that had penetrated the crumbling boards, the shed held evidence of other lodgers. Two neatly made nests, each a mixture of moss, leaves and shredded plastic hinted at the presence of Wood Mice, something confirmed by the numerous Hazel nuts, carefully opened at one end by sharp teeth. There were woodlice in the damp corners and a huddle of snails in an old terracotta pot. It was the spider webs and their silent occupants that were of greatest interest, however, and these covered much of the wall space, particularly so in the corners and where uprights held the horizontal lapboard in place.

A few of the spiders were sizeable beasts; these were large Tegenaria house spiders of the sort encountered in the house during August or September, when the newly mature males wander in search of receptive females. The size of these arachnids makes them the bĂȘte noir of those suffering from arachnophobia but I find them rather engaging.

I could not be sure which of the eight Tegenaria species I was looking at, even though there were clear variations in size. Several can only be reliably identified through careful scrutiny under the microscope and hybridisation between species is rampant in some areas. The larger individuals seemed to occupy the largest webs, perhaps reflecting some variation in age since house spider webs are long-lasting. The silk used in these webs is not sticky, which may explain their longevity, and a web may be used by a succession of spiders over time as the original occupants die and are replaced.

The chances are that most of these spiders were females, since the mature males typically die early in the winter, having mated and leaving the mature females and immatures to sit out the cold weather. Come the warmer conditions of spring, the mature females should see an increase in prey availability and the resources needed to develop the eggs that will be deposited in a series of egg sacs. Each egg sac, made of white silk, is about the size of a small marble and may be decorated with prey remains; it will be deposited close to the web. I could not see any egg sacs, so I hoped that these spiders, about to be evicted from their current home, would find somewhere else to set up.

House spiders also occur away from human habitation, living under debris, within tree cavities or within rock crevices, but no doubt the replacement shed would soon be occupied.

Monday, 27 February 2012

Breckland pines


Breckland is characterised by its dry soils, open landscapes and lines of twisted pines. It is the pines that you first notice as you enter Breckland from the southwest, tracking up the slight incline and away from the richer soils beyond.

These pines are the ghost of an older landscape, deliberately planted as hedgerows but left untended, allowed to develop into mature trees. Some of the trees are heavily contorted, as if shaped by the wind, while others stand upright with a degree of formality. Some are closely spaced, others separated; some planted on a slight bank, others not. It is likely that the pines were chosen because they could cope with the light, poor quality soils; with careful management they could be maintained in dwarfed form to produce a hedge.

It is not known precisely when the pine rows were planted but the available evidence suggests that they were first established some time after 1800, around the time of enclosure within much of Breckland but not directly related to it. The peak period of planting probably happened between 1815 and 1820 but it certainly continued to at least 1829, when a description of the planting of such a hedge appears in the journal of a certain D. E. Davey, documenting his excursions through the Suffolk Brecks.

Today the remaining pine rows are concentrated within the old parish boundaries of Eriswell, Icklingham, Elevden and Thetford. Others would have disappeared under the plantation forest that was established between the First and Second World Wars, so it is no longer possible to determine how widespread the practice was. That we do not see wider use of Scot’s Pine in this manner suggests that estate owners soon discovered that it was, ultimately, a poor choice for hedging. The agricultural depression that followed may have also contributed to the decline of the rows and most likely explains why the pines were freed from management and allowed to grow-on to their present mature forms.

Looking at the pines it is difficult to associate them with a sense of antiquity. They may be two centuries old but they lack the ‘veteran’ gravitas that one associates with Oak, Yew or Ash. Perhaps their image has been cheapened by the acres of plantation conifers that dominate much of Breckland; wood grown as a crop to be pulped for paper or lashed to the roof racks of Sunday morning DIYers. To me, however, even with their deliberately planted origins, these pines hint at an older landscape, a heathland of scattered trees and sandy soils. It could be said that the pines which mark the gateway to the Brecks have broken free from their hedgerow shackles to take on iconic form.

Tuesday, 21 February 2012

Goldfinch with abnormal plumage

video

This Goldfinch has been visiting the garden over several weeks. In place of the black heading markings is an area of white, meaning that this bird is suffering from some form of plumage abnormality. The BTO is running an Abnormal Plumage Survey and wants to hear from you if you have seen a bird with unusual plumage, perhaps a Blackbird with some white feathering. You can access the BTO pages on abnormal plumage here.

Tuesday, 7 February 2012

Networks


In this land of large fields and monster blocks of plantation woodland, it is the rivers that provide the all-important linkage across wider spatial scales. These are lowland rivers, more often than not a steadily flowing meander that shifts its liquid bulk across the broad, barely perceptible valley floor. At various places along their length these rivers are controlled, forced into channels that meet our needs: the neat, concrete-sided river that flows through town; the high banked channel into which the drains feed to keep the low lying land dry.

If you could see a natural river from above over a period of many decades you would see a river that is alive, its course shifting over time as it throws out new meanders, splits into multiple channels and reforms. These shifting courses underline the power of the river, brought about by the volume of water that is carried ever seawards.

My local river forms part of my own natural rhythms. It is my guide as I walk to work; it is my companion when I seek somewhere quiet to pause. In summer it is clear, the green of countless waterweeds gently moving in the current, but come winter it turns dark and brooding. The river annotates the seasons, catching the blossom of spring and the spent leaves of autumn. At times it is tranquil, its surface a flat reflection of bright skies and white clouds. On other occasions it is fierce, the rush of water over the weir gates into the plunge pool below, whose depth you can only guess at.

It is the wildlife that brings the river to life, the other creatures with which I share its watery environs. An egret hunting in one of the shallow feeds that drain into the main river; the electric blue of a Kingfisher as it rushes upstream piping alarm, and the rare glimpse of an Otter as it slips silently into the water in the shade of the far bank. These creatures make use of the river along its length, a pattern repeated on other rivers in other places. It is a corridor that connects many different habitats, providing linkages that would not otherwise exist.

There is a flip-side to this connectivity, however, in that damage done in one place may be felt elsewhere along the river’s length. The plastic bag carelessly discarded here may choke a creature many miles downstream. Sample a river upstream of a town and compare this with what you sample downstream of that same town and you’ll gain true measure of our impact. The river is not about the here and now; it is connected and we must understand that if we are to care for it properly.

Saturday, 4 February 2012

Roads take toll on Barn Owls


The surprisingly mild conditions that we have seen this winter are likely to have been beneficial for the county’s Barn Owls. Cold weather, in particular periods with snow cover, high winds and prolonged rain, can all cause major difficulties for Barn Owls which, unable to find favoured small mammal prey, soon succumb to starvation. One of the reasons for this is that Barn Owls carry little in the way of fat reserves, something that limits their global breeding distribution to those parts of the World where the winters are less hostile. The northern limit of the Barn Owl breeding distribution falls, for this reason, in northern Scotland. Even here, the species only just hangs on, restricted to lower altitude sites and the population quickly knocked back by a particularly poor winter.

Another major cause of Barn Owl mortality is collision with traffic on our increasingly busy roads. Roads fragment Barn Owl hunting ranges, leaving the birds no choice but to cross them; flying characteristically low they are often hit by a passing car or lorry. One estimate suggests that as many as one in three of the Barn Owls born each year will end up dead on a road. This statistic was brought home to me the other morning when, driving south into Suffolk I came across the corpse of a freshly dead male Barn Owl. This proved to be a young bird, the talon comb on its foot scarcely developed. It is thought that this comb is used in older birds to maintain the plumage, particularly that on and around the all-important facial disk.

It appears that some young Barn Owls may actually be drawn to roads by the small mammal populations supported within the roadside verges. On quiet country roads, these verges can provide important hunting opportunities, particularly where the wider landscape is dominated by more intensive arable. I have seen birds working these verges at various sites across the north of the county, often with great success, judging by the numbers of Field Voles and Wood Mice taken. However, where these verges sit alongside busier stretches of road, then it is often only a question of time before a bird is killed.

With so much bird-ringing activity directed to increasing our understanding of Norfolk’s Barn Owls it is likely that many of the Barn owls found dead on our roads will be carrying a numbered ring. If you come across a dead Barn Owl, please do stop (if you can do so safely) and check. The number of the ring will almost certainly link the bird to a local breeding site and help researchers to build up a picture of where these birds face the greatest risks from our road network.

Friday, 3 February 2012

Jack Snipe


The presence of a Jack Snipe on the local nature reserve last week, once again highlighted the value of birdwatching a local patch. The finder, a colleague from work, visits the site on a regular basis throughout the year. Every now and then one of these visits turns up something unexpected or unusual, just reward for the amount of effort put in to watching the same site and its visiting birds on many occasions throughout the year.

Although the Jack Snipe is a smart little wader, it is rather secretive in its habits and rarely strays far from damp, well-vegetated cover. If you are fortunate enough to see one from a bird hide then you may well be treated to its furtive, crake-like feeding behaviour. The bird will tend to pick at food items on the surface, probing less often than its more familiar relative, and sometimes bobbing its body up and down like some peculiar clockwork toy. Your more typical view of a Jack Snipe is to see one launch itself from the piece of vegetation next to which you have just placed your foot. Once in the air, the Jack Snipe tends to stay rather low, flying in a straight line (Common Snipe zig-zags and gains height rapidly) before quickly dropping back down into suitable cover.

While the nature of its escape might suggest the Jack Snipe to be somewhat weak when it comes to flight, it is actually a long distance migrant, with some birds from the Siberian breeding population known to winter in sub-Saharan Africa. Others, from the western end of the breeding range, pass through Britain in the autumn, with some overwintering here. Arrivals here tend to begin in mid-September, increasing through October then dropping before the return movement in April.

The migratory nature of the species, coupled with its somewhat secretive habits and choice of feeding habitats, mean that we have a very poor understanding of this species. Of particular concern is the degree of uncertainty surrounding estimates of its population size. If we do not know how many Jack Snipe occur in Europe (or beyond) then how can we reliably determine if their populations are in difficulty, perhaps declining with the loss of favoured habitats to afforestation or land drainage.

While both Woodcock and Common Snipe are familiar birds to me, often seen on my ramblings around the Brecks, the Jack Snipe is a bird that I have seen only on a handful of occasions. I might just make a few more visits to the reserve over the coming week to see if I too can strike it lucky. Even if I don’t, there is always the chance that I might stumble across something else equally fascinating.

Thursday, 2 February 2012

Pink-footed Goose will have a tale to tell


It is amazing to see so many Pink-footed Geese out on the marsh. The numbers here today are significantly greater than I have seen on the site before and are more reminiscent of the North Norfolk coast. I am, instead, far inland, walking the marshes that border the River Yare not far from Norwich. Admittedly, the numbers of winter pink-feet on these marshes have increased over recent winters, so the presence of such a large flock should not be that unexpected.

As I have remarked before, the ‘grey’ geese can represent something of an identification challenge for the birdwatcher, testing skills on dull, late-winter afternoons. It doesn’t help that this particular site often holds several different goose species, individuals of which may mix together. This flock of pink-feet is straightforward enough though. With the sun behind me, and the advantage of a flood bank from which to scan, I steadily work my way through the flock, tally counter clicking away in my hand as the numbers steadily increase.

There is one particular individual that catches my attention, however, because it is sporting a silver-grey neck collar on which are written three large letters. This is a bird that has been caught by researchers, either somewhere within Britain or elsewhere in Europe, perhaps even in Iceland. While the use of these neck collars does not do the birds any harm, it is carefully regulated, remaining a tool for those studying the movements of these birds between different sites, or indeed different countries. I know that I will be able to send this record off and, by doing so, add another piece of the jigsaw to help researchers understand which wintering sites are important to which breeding populations. If we are to protect and conserve these geese then we need to know as much as possible about where they go and when.

Britain is a particularly important wintering destination for these geese, with virtually the entire Icelandic breeding population, and most of the east Greenland population, spending the winter here. While many favour coastal saltmarshes, many more now move onto arable land, where they can feed on sugar beet, waste potatoes and barley stubble. The switch to these new food sources highlights the adaptable nature of these geese, something that can also be seen in their wintering strategy. Individual birds have large feeding ranges but still have a favoured core area within this. The geese will move between sites, especially as the winter progresses and they disperse away from the places at which they initially staged upon arrival. This approach means that they can respond to local food availability and, by doing so, presumably increase their chances of getting through the winter in good condition.

Wednesday, 1 February 2012

A tree of damp places


At this time of the year the riverside alders often hold chattering flocks of siskins and redpolls, noisy affairs that pull your gaze to the outermost branches and to the fidgety silhouettes of these small finches. The tree itself has a ‘twiggy’ silhouette and, with its characteristic female cones, can appear somewhat fuzzy around the edges.

Alders are often encountered in riverine surroundings, either along the river banks themselves or on the damp ground that occurs where fen and carr sit nearby. You might think that this suggests an association with waterlogged ground but this is not the case. Alder is more particular in its habits and favours ‘flushed’ soils, i.e. those where there is a movement of water through the soil. Riverside soils provide these conditions, as do spring-lines and similar features elsewhere.

We have a fair bit of alder on the Nunnery Lakes Reserve in Thetford, where it is sometimes cut as part of the wider management of the site. The timber is white when freshly cut but quickly takes on an orange-red colouration through the process of oxidisation. Interestingly, it made ideal charcoal for the production of gunpowder and this may explain the presence of planted alder woods close to sites where gunpowder used to be produced. The timber has also been used in the framework supporting the banks of canals, in the handles of farm and garden tools and as lure for woodworm. Although found across the whole of Norfolk, alder is more common in the east of the county, where it has traditionally been viewed as the first coloniser of early successional habitats.

Alder is a tree whose shade I enjoy in the summer, when sat by the river, or whose rough bark I scour for insects and spiders throughout the warmer months. During the winter it is the crown of the tree that I watch, scanning for finches that have come to feed on the tiny seeds, held within rather delicate and open-looking cones. I can remember cursing these cones as a child as it was all too easy to leave a fishing line entangled within their grasp. Compared to other trees (think of oak, yew and elm) the alder does not attract that much attention and it remains a largely overlooked part of our countryside. This is a real shame because I think that the alder has a strong character, in part defined by its waterside habits but also by its twisting branches, thick mass of smaller twigs and rich-coloured catkins. The tree did catch the news a few years ago, however, when a Phytophthora fungus was found to have killed roughly one in ten trees over parts of Wales and southern England.