Friday, 18 November 2005

Be prepared for busy bird tables

There was ice on the car windscreen the other morning and a definite chill in the air. Another indication of the drop in temperature was an increase in the numbers of birds visiting my garden feeding station. In with the regular greenfinches, were chaffinches, blue tits and coal tits, attracted by the sunflower hearts that I provide throughout the year. Providing food in this way gives a good indication of the numbers of birds around and of the availability of ‘natural’ food in the wider countryside. Towards the end of summer there is a noticeable drop in the numbers of birds visiting the garden, as birds that may have been breeding locally move out into the surrounding farmland and woodland to exploit the autumn bounty of fruits and seeds. Evidence from the 16,000 gardens that participate in the British Trust for Ornithology’s Garden BirdWatch scheme shows that this autumn trough is a national feature, repeated in gardens up and down the country. It is only when the bounty begins to decline, that the birds turn to gardens and the food that we provide.

Just how early into the winter birds like siskins, chaffinches and bramblings move into gardens is, in part, dependent on the size of the seed crop produced by trees like beech and sitka spruce. In some years, when the seed crop is particularly large, there is little need for these birds to visit gardens but in those years when seed is scarce, they can arrive early and in large numbers. The size of the seed crops of these two tree species follows a roughly four-yearly cycle, a strategy that enables the trees to reduce the impacts of seed predators on their precious seeds, with years of peak seed production followed by a number of years of much smaller crops. It just so happens that this year the quantities of beech seed (known as beechmast) and spruce cones are both small, something that has seen siskins arriving in gardens across East Anglia earlier than they would normally appear. This hints at a busy winter ahead, with large numbers of finches usng garden feeding stations. Because there tends to be a degree of synchrony in the size of the seed crop across large areas, we are also likely to see increased numbers of birds arriving here from Scandinavian forests. If, as the weather forecasters are predicting, we end up with a severe winter then this too will increase the numbers of birds visiting gardens. Joining the finches will come farmland buntings and thrushes, seeking the food needed to get them through the worst of the winter weather. So now is the time to stock up on birdfood, prepare yourself for the winter ahead and the sight of busy bird tables.

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