Girton Birdwatch - January 2013
Towards the end of October birders were starting to wonder about what had happened to our winter migrants which were a bit slow in arriving. In particular there appeared to be a dearth of redwings and fieldfares. The British Trust for Ornithology (BTO), with its superb 'bird-track' system, was able to demonstrate that the birds which normally arrive here from Scandinavia were more than two weeks behind their usual autumn schedule. Our strange spring, summer and autumn weather, it was hypothesized, and its effects upon the natural harvest of fruits and berries, if duplicated in Russia and Finland, had probably affected the ability of these migrating thrushes to pile on the fat reserves necessary to see them safely across continental Europe and the forbidding North Sea to our shores. Shortly afterwards, however, the situation changed dramatically as thousands of birds started to make landfall, first at Spurn Point on the Humber estuary and later on the Norfolk coast. Observers on Humberside counted, in one night, 21,000 redwings, 10,000 blackbirds, 9,000 fieldfares, 800 song thrushes, 57 ring ouzels and 10 mistle thrushes. Later, on the Norfolk coast, tens of thousands of redwings and other migrants were reported hanging from every available bush and tree.
This is always a good time of year, of course, to spot jays as the trees lose their leaves and the birds go foraging for the available acorns but October saw unusually large numbers arriving on the east coast, primarily from the huge forests of Scandinavia and points north. At Cley, Norfolk, 278 were recorded in a 3 hour watch, while in Kent several flocks - including one of 34 birds - were seen coming in off the sea, while at least 668 passed over Hunstanton. These figures might not seem that large, compared with redwings say, but for jays they are significant. Jays are not normally associated with the term 'irruption' ( a dramatic, irregular migration of large numbers of birds to areas where they are not typically found, possibly at a great distance from their normal ranges), but this seems to be what happened.
A more 'usual suspect' is the brambling. This northern version of the chaffinch breeds in Scandinavia and northern Russia and visits Britain every winter but its numbers vary considerably. They are typically found among chaffinch flocks but the more that arrive the greater likelihood they are to cohere in compact and exclusive groups. They prefer beech woods, and are fond of beech mast but, if these fruit/seeds have been adversely affected by the weather then you may be fortunate to find them in your garden. In winter both sexes have an orange breast and some dark spots on their flanks. The male's head has a slightly piebald appearance with the black areas softened by pale feather fringes.
However, don't assume that more familiar birds are not part of an irruption. Every winter large numbers of song thrushes, blackbirds and starlings arrive here from the Continent. Although this is an annual occurrence numbers may still fluctuate widely depending on the weather here and at home, plus the availability of food. The blackbird tossing up the leaves in your garden is not necessarily the same one seen tugging worms out of your lawn in the spring, but possibly a Continental interloper.
The 'irrupter' we were all probably hoping to see was the waxwing. Small numbers arrive here each winter but when the berry crop at home fails then vast numbers can make their very welcome way here. The winter of 2010-11 broke all sorts of records and large groups were found across the U.K. searching for food (a great favourite being rowan berries but pyracantha, cotoneaster etc are also favoured. In spring 2011 a flock of about 20 stayed for half an hour on our large maple tree apparently eating the flowerbuds). Last year visitors to Oakington Garden Centre who asked after the birds seen feasting on the white rowan the previous year were disappointed to be told that that was not an annual occurrence and that there was hardly a waxwing to be found nationally, with those that did come tending to remain firmly in place on the east coast. Why the absence last year? Unfortunately the cold weather and/or shortage of food that encouraged large numbers to move south and west in 2010-11 probably thinned out the population, as did the hazards of migration. The smaller numbers which remained presumably had an easier time finding food at home and so had less need to move. This combination of factors means that irruptions tend to go in cycles and are by no means regular (or, if regular, occur in four year cycles).
However, the early signs were that 2012-13 was building up to rival 2010. On November 16th a single bird was over Windsor Road but by the 18th seventeen were at Fowlmere, with ever larger numbers of birds being reported in the region and elsewhere nearly every day. By mid-December the county was awash with these lovely birds and the Cambridge Bird Club's web-site was featuring a 'waxwings of the day' item. On 26th November there were 30+ at the end of Pepys Way in the village while three days later 78 turned up in Oakington; the 5th and 6th of December saw upwards of 50 at Histon Road Cemetery and about 120 were in Storey's Way. If you haven't seen them before then this could be the year for you. They are an easy bird to spot being so distinctive, found in flocks and attracted to car parks and other areas with isolated stands of their favoured food plants. At first glance they can be mistaken for starlings so give any flocks the once over.