Girton Birdwatch - April 2010
There's a hint of spring in the air as I write this and it won't be long before our migrants start to arrive; the Avocets have already turned up in decent numbers at the Cam Washes. However, the long hard winter - which is bound to have had deleterious effects on some of our smaller birds - has also brought its rewards. A few Waxwings have visited the area, with a group of four setting up residence near the Panton Arms in the city, while a Rough-legged buzzard has been seen in the vicinity. Closer to home we have had Redpolls in the Northfield area, a large flock of Yellowhammers in Thornton Road, male and female Blackcaps throughout the village, and reports of a Nuthatch calling down Washpit, where Kingfishers have also been seen.
It's been a long time since I've seen a Redpoll - the last time being 1977 at RSPB headquarters, Sandy. I missed the Mealy Redpolls which turned up at Titchwell a few years ago. The Redpolls' usual habitat is moorland and heath, especially that containing birch, alder and willow scrub, and lowland coniferous plantations. However, they are increasingly starting to visit gardens and local bird websites have carried several reports of their presence in and around gardens.
The Redpolls are very small finches with grey-brown streaked plumage, red foreheads and black chins. Breeding males have plenty of pink on the breast and rump, while the female has a brownish rump and virtually no pink, except for the forecrown. They have yellow bills and deeply notched tails. The mid-twentieth century saw a dramatic rise in redpoll numbers - roughly four-fold from the mid-60's through the 70's, with a downward trend beginning in the 1980's, so that by the 90's numbers were back to 1960's levels. They feed mainly on seeds, especially birch seeds, although those of alder, sallow, larch and spruce are also enjoyed. It was the dramatic increases in these invasive scrub species, as well as the widespread planting of conifers, that helped explain the noticeable rise in Redpoll numbers during the mid-twentieth century, and the equally dramatic fall in numbers as the young plantations reached maturity and became unsuitable for the birds. The falls have continued, however, and according to bird experts, require further explanation.
Yellowhammers are also seed-eaters and their numbers have been affected by the grubbing up of hedges and the loss of heathland. Although they are not particularly shy of people they tend to avoid areas of human habitation, rarely entering gardens even in the countryside, so the flock of ten or more visiting Thornton road is really quite exceptional.
Bob Benton tells me that attempts are to be made to attract Tree Sparrows to our very own nature reserve at Town End Close, which was donated to the village by David and Margaret Wallace, now sadly both deceased. The Tree Sparrow is in even greater trouble than its close relative the House Sparrow, which has declined markedly in recent years. Older people will remember seeing large flocks of House Sparrows wherever they went in this country, whereas now, the six which enter our garden on a regular basis must be considered unusual. In the past they were so common as to be considered a pest and a threat to grain supplies, and were persecuted. In the 1860's the Sussex Express reported 'The thirteenth anniversary of the Sparrow Club, Rudgwick, was celebrated with a dinner at the Cricketer's Inn On reference to the books it was ascertained that 5,321 bird's heads had been sent in by members during the year, 1,363 being contributed by Mr W. Woodberry, to whom was awarded the first prize'. The more recent decline - London lost three-quarters of its Sparrows in just six years (1994-2000) - has not been satisfactorily explained, although Cocker and Mabey have itemised a number of possible reasons, some more imaginative than others: ' the line-up of suspects includes cats as well as the customary avian scapegoats - magpie and sparrow hawk - unleaded petrol, increased use of garden pesticides and, more bizarrely, mobile phones (said to hinge on electromagnetic waves that interfere with the bird's capacity to reproduce or navigate). Birds Britannica contributors have suggested modern roofing methods that bar access to the breeding sparrows (now widely viewed as an important problem) and the lost tradition of shaking crumbs from the tablecloth'.
Most people would recognise the House Sparrow, but few will have seen a Tree Sparrow, which has undergone a massive 95% reduction in the last 25-30 years. Its most distinctive feature is its chestnut coloured crown and nape - the House Sparrow has a grey cap and black bib - and its rather isolated black spot on a white cheek. It is also somewhat smaller and slimmer than the House Sparrow and has generally brighter plumage.
Nest boxes are to be put up at Town End Close in an attempt to attract these handsome birds to the area but, as no one is very sure why they have declined so markedly, we should not expect miracles. Dutch Elm disease, and the subsequent death and felling of so many trees, has been suggested as reducing the number of breeding holes, so nest boxes may do the trick, although some authorities believe that reduced food supply is the main cause of their decline, and much more difficult to remedy.