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February 10, 2006
Decline of UK House Sparrow Better Understood?
The Independent newspaper highlighted the plight of the British House Sparrow back in 2000 with the offer of a £5,000 prize for the first properly accepted scientific answer.
Many suggestions have been put forth. Magpies, cats, pesticides, peanuts, climate change and home improvements are among the myriad cited for the sparrow's startling disappearance from London and other towns and cities.
The prize has never been claimed.
Kate Vincent, a postgraduate researcher at De Montfort University, Leicester, has for the past five years been closely examining house sparrow breeding success for her PhD thesis.
Her research appears to point to one of the theories for the birds' decline - a similar decline in the numbers of the insects and other invertebrates that sparrow chicks need for the first few days of their lives. In their first week of life, the chicks need animal protein in the shape of small grubs, flies, aphids and spiders.
Over three years, Vincent put up more than 600 nestboxes on houses in Leicester and the city's suburbs and her finding was that, in the summer, considerable numbers of sparrow chicks were starving to death in the nest.
The chicks that were dying were largely in the sparrows' second brood of the year, providing an explanation for the population decline as a whole. As many young sparrows do not survive their first winter, every year the species needs two or three broods (of four chicks each) to keep the population at least level. If the second brood is failing, the population will start to fall.
Vincent found an 80 per cent success rate in the first brood, but only a 65 per cent success rate in the second.
The strong implication is that insects and other invertebrates are becoming much scarcer in Britain in summer - which, although Vincent's research does not specifically prove this, is suspected by wildlife researchers.
Posted by Surfbirds at February 10, 2006 04:09 AM
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