Look out for Tree Sparrows

As I have noted before, the Tree Sparrow is one of those birds that I catch up with from time to time. A substantial and long-term decline has greatly diminished the numbers of Tree Sparrows and it is becoming increasingly difficult to see these delightful birds at many of their former haunts. Every now and then, one will pop up just when least expected. There was the small flock that suddenly appeared in my BTO Bird Atlas square back in February of last year (I have not seen them there since) and more recently two have taken to visiting a garden just around the corner from where I work on the edge of Thetford. The appearance and subsequent disappearance of flocks (and indeed breeding colonies) is well known; it also makes studying them all the more difficult.

Tree Sparrows are thought to have declined because of changes in the way in which we manage our farmland. The move from spring sown cereals, with their associated winter stubbles, to winter sown cereals has removed an important food source during a critical time of the year and it is possible that falling overwinter survival rates may have driven the decline. However, other factors may also have been involved.

One particular aspect of Tree Sparrow ecology that has been of interest of late, is the degree to which birds move away from the breeding colony at the end of the breeding season. In order to examine this, Keith and Ann Herber have been colour marking Tree Sparrows at a breeding colony near Thornham for a number of years. Their efforts have revealed that most birds generally leave the breeding area before the middle of October, returning again during late March or early April. However, Keith and Ann really want to know where the birds go during the winter – do birds spend the winter in the local area or do they move further afield? In order to answer this question, Keith and Ann need sightings of birds carrying colour rings; perhaps you have them visiting your North Norfolk garden during the winter months?

Another aspect of interest to the researchers is why so many breeding birds fail to return to the breeding colony the following year. Have these ‘missing’ individuals failed to survive the winter, or have they chosen to breed at another breeding colony elsewhere.

Do look out for colour-ringed Tree Sparrows, especially up on the North Norfolk coast around Holme, Thornham, Choseley, Ringstead and Titchwell. If you are fortunate enough to see one, do forward the details to Keith and Ann Herber (07785-920044 or email keith.herber@btopenworld.com). I know that they will be delighted to hear from you.

Catching up with old friends

Hunkered down just off the verge I feel like part of the fen, a large sod of thick peaty soil, newly turned by the plough to be weathered by a wind that races in off the North Sea. It’s at times like this that the words of Noel Coward spring to mind; ‘very flat, Norfolk’ and little to stop a wind that has its chilly origins many hundreds of miles to the northeast. I am pressed down low to escape the worst of the wind, to keep myself warm and, more importantly, to keep my telescope steady as I scan the distant flock of Whooper Swans feeding in the next field over.

Even though I feel exposed and uncomfortable under these grand skyscapes, I try to come here each winter to seek out the swans that feed on the fields around Welney. For the swans too, this is something of an annual pilgrimage; an autumn migration that draws them here from breeding grounds spread across Iceland. It is the combination of secure roosting sites and nearby feeding opportunities that attracts the swans and as many as 3,500 may be present during the middle of winter.

Many of the birds arrive in small family parties, the youngsters readily distinguishable from their parents. Some of the birds carry rings, invariably fitted on the breeding grounds, with a few individuals additionally marked with special ‘darvic’ rings that can be read at a distance by telescope. Such rings enable researchers (and interested birdwatchers) to collect information on the whereabouts of individual birds without the need to recapture them. Over time, subsequent resightings of an individual can help to build up a detailed picture of its wintering grounds, together with arrival/departure dates for the movements between breeding and non-breeding sites. Records can be submitted to the Wildfowl and Wetlands Trust who will then send back a spreadsheet detailing the history of the bird(s) you have seen. Among those that I recorded during last winter was an individual first ringed in August 2004 at Bardardalur in Iceland. This particular individual has wintered at or near Welney each winter since. The reports for certain other individuals show a degree of exchange with other sites, including the Wildfowl and Wetlands Trust reserve at Martin Mere in Lancashire and the River Tweed catchment in the borders.

As well as the challenge of reading the rings as the swans feed, there is the delight of noting down a ring number and knowing that it will add to our understanding of these heavyweight waterfowl. There is also the sense of expectation that you might just catch up with an old friend, a swan you have seen in a previous winter.

A bit of added colour

Bright and colourful, the Mandarin Duck is a species that is evidently exotic in origin. First introduced into Britain before the middle of the Eighteenth Century, this delightful little duck has now established a sizeable feral population. The current population, with its strongholds in Berkshire, Surrey, Buckinghamshire, Somerset and Gloucestershire, most likely is the result of escapes and introductions that took place during the first half of the Twentieth Century. Typically secretive in habits, the Mandarin appears to have established a population numbering several thousand individuals, virtually unnoticed. Perhaps this is not the only reason why the Mandarin has not attracted our attentions in quite the same way as certain other exotic waterfowl. There have been no obvious conservation problems associated with its arrival. In fact, up until recently, it was thought that Britain held a sizeable proportion of the world population, with numbers in the native Asian range believed to be in severe decline. Fortunately, new estimates of breeding numbers in China, Japan and Korea suggest that the species is doing rather better there than previously supposed.

I remember seeing my first Mandarin whilst undertaking a hiking expedition towards one of my Cub Scout badges. To see such a brilliantly coloured bird (it was a male) on a tiny stream running through a block of woodland was a revelation. Here was a bird that looked even more stunning in the flesh than in those of my bird books which sometimes over-egged plumage colours. Since that first encounter I have stumbled across Mandarins on a fairly regular basis, though less so within Norfolk.

This pattern of encounters seems to be changing and, since 1995, the species can no longer be considered scarce within the county. Pairs have been reported breeding in Norfolk since the 1960s and there have been a number of high profile releases or escapes of birds, most notably at Sandringham where eight ducklings obtained from Windsor were released in 1973. A look through Norfolk Bird Reports supports the nortion that there has been a notable increase in sightings since 1995, with some sites now just about guaranteed to ‘deliver’ the species for the birdwatcher. Top amongst these has to be Felbrigg Hall, where a dozen or so individuals may be seen on the lake at this time of the year. Interestingly, these little ducks do not gather in large flocks, even though they are largely sedentary in nature. Nesting in tree cavities and feeding throughout the winter on tree seeds (such as beech mast and acorns), the grounds of Felbrigg must be a rather favourable habitat for Mandarins. If you get a chance to visit them, please do and add a splash of colour to a dull January day.

Crow

The crows are ever-present companions on my walks these days. More often than not their presence is a silent one; a hunched form perched high in a bare tree or a ragged shadow slipping across the darkening winter sky. On such days, with brooding clouds and a bitter wind, it is easy to think of them as harbingers of an approaching storm and I can understand why crows and ravens have a central role in much of our folk heritage. Yet they so often remain bit-part players, a supporting cast to the seemingly more noticeable birds and animals with which I share my ramblings.

Throughout literature, the crow has nearly always been regarded as a sinister bird, a creature of ill-omen. Perhaps some of this reputation was gained by the crow’s association with death; as a scavenger it would have been present at the aftermath of great battles or quick to exploit the macabre offerings available at the many gibbets and gallows that once dotted our countryside. It follows that if the crow (or raven) was present at the time of death then it may have had some supernatural role associated with the spirit’s journey to the next world. Other traits central to the success of various members of the crow family may also have lent weight to a belief in their having supernatural powers. Often long-lived, extremely bright and with a good memory, crows may exhibit behaviours that seem too advanced for ‘mere birds’. Odin was held to have two ravens, named Hugin and Munin (Thought and Memory), who flew far and wide to bring him information. Anyone who has studied crows closely will know of their ability to retain information and such abilities may have been revealed when crows were kept as pets.

Other powers have also been associated with various members of the crow family. The traditions of ‘crow’, ‘raven’ and ‘jay’ stones all associate some power with these birds, which is then held in a stone. Holding a ‘crow’ stone conferred upon the bearer the gift of prophecy, while holding a ‘jay’ or ‘raven’ stone was believed to render you invisible.

One aspect of crow folklore that has long interested me is the tradition of warriors or other people becoming crows. A local Cornish legend has it that King Arthur became a chough (or possibly a raven) after his death, while there is a French tradition that has wicked priests turned into ravens and bad nuns turned into crows! While a modern day naturalist might laugh at such tales, they do provide an interesting insight to the degree to which we have now become divorced from the natural world around us.

A changing landscape

The landscape around here is changing; each time I visit this far-flung corner of Surrey I find that new vistas have been created by the removal of the mature pines that had come to dominate the poor sandy soils. The clearance of these trees is part of a concerted attempt to re-establish the great blocks of heathland which have been shaded out over the years by the maturing conifers. It is a grand project, made possible by the efforts of the National Trust, but carried out in a way that recognizes the importance of gradual recovery rather than an abrupt overnight change. I have seen similar schemes elsewhere, some of which have left behind them scarred and battered landscapes that will be slow to heal.

That the change should be gradual – a small section here, another there – is important because there are species that will have benefited from the presence of mature conifers and which will now need to readjust their populations to a new equilibrium. Species like Coal Tit and Crossbill among the birds, and many different beetles and other invertebrates among the lower orders. Other species will welcome the change and their populations are likely to expand accordingly. Most of these will be heathland species that will take advantage of the new opportunities on offer. With luck, the Woodlarks and Nightjars will return in increased numbers, bringing their songs back to this part of the county. For mobile species, such as these, there is a good chance of recovery, but other species may need assistance. Some, such as the Heath Tiger-beetle, have declined to such an extent that they may not find the newly restored habitat without some input from us.

This sort of landscape-scale habitat restoration appears to be becoming increasingly common. It is certainly to be welcomed, especially by those of us who feel that nature should be conserved within the landscape rather than within token nature reserves whose diminutive size often isolates the populations of plants and animals from others of their kind. Of course, a landscape-level approach to the conservation of wildlife depends upon the pressures being placed on the land. If there is a pressing demand for land for agriculture or housing then it becomes more difficult to put it aside for wildlife. Actually owning the land makes it more likely that it can be managed in a way that is sympathetic to wildlife and this is why many of our county wildlife trusts, Norfolk Wildlife Trust included, are now buying up land in specific areas to re-establish lost or diminished habitats. Such schemes also increase our opportunities to interact with nature, something which is becoming increasingly important in our busy lives.

Garden feeders reveal an army of diners

Spending some time at my parents’ house over Christmas has enabled me to take stock of a different garden feeding station. Although many of the bird species putting in an appearance at the hanging feeders are familiar, others would constitute a red-letter day were they to appear in my garden at home. Species like Bullfinch, which are such regular visitors to my parents’ rural patch, seem to like the fact that it is well connected by a network of hedgerows to the series of small woodlots that are a feature of this rural Wealden landscape. By comparison, the attractions of urban Thetford are unlikely to suit the shy and retiring nature of this boldly marked finch.

One feature that has struck me over the past few days is the sheer volume of birds passing through the feeding station. It is clear from the composition of the visiting flocks that a good number of birds take in the garden as part of a wider foraging circuit that also covers much of the local woodland. The nature of the woodland itself is evident from the visiting birds; the stands of beech and oak contributing the Blue and Great Tits, while the blocks of conifers that still adorn much of the local heathland are no doubt the source of many of the Coal Tits and Goldcrests.

Some idea of the numbers of birds involved can also be gained from a short spell of ringing. As a licensed bird ringer, I am in the fortunate position of being able to catch wild birds and mark them with specially developed metal rings. Each ring carries a unique number and, should the bird be subsequently found, this provides an insight into its longevity and movements. Many people assume that ringing birds only tells us where they go (think of Swallows wintering in Africa) but researchers also use the information to examine survival rates and productivity, two vital components that ultimately influence whether a population increases or diminishes over time.

In this particular instance, however, one of the by-products of ringing in my parents’ garden is an understanding of the numbers of birds passing through the feeding station. When you look out the window there, you may see half a dozen Blue Tits around the feeders at any one time and it would be easy to assume that it is the same half dozen individuals that you see at various times throughout the day. Stick up a net and fit the individuals that you catch with rings and it soon becomes apparent that you are talking about a population of many dozens of Blue Tits passing through the feeding station over the course of a short winter’s day.