Azara Blog: Study on the decline of house sparrows in Britain

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Date published: 2006/02/09

The BBC says:

The decline of the house sparrow, one of Britain's best known birds, could be down to a lack of insects and spiders during the summer months, experts say.

A De Montfort University team claims adult sparrows are struggling to find enough food to feed their chicks in the early stages of their lives.

UK bird charity RSPB said measures that boosted insect numbers could also help arrest the sparrows' decline.

This included growing deciduous trees and shrubs and cutting insecticide use.

In August 2002, the house sparrow was added to the Red Data list of bird species of conservation concern because their decline had been more than 50% in the last 25 years.

Between 1977 and 2000, house sparrow (Passer domesticus) numbers in the UK declined by 65%.

Kate Vincent, of De Montfort University in Leicester, put up more than 600 nestboxes around the East Midlands city to study the birds' breeding success, chick condition, diet and feeding habits.

Ms Vincent found that chicks were more likely to starve if their diet contained a high proportion of vegetable matter or ants, and less likely to starve if their diet contained a high proportion of spiders.
...
Thus far, there is no evidence that the birds' invertebrate prey have fallen in abundance in urban and suburban of Britain.

But Kate Vincent says it provides a plausible mechanism for the observed declines in populations of the birds.

Well the BBC article does not give enough details, but this sounds like stretching data to provide a desirable interpretation. For one thing, the study was in Leicester. Is there any plausible explanation why the city would have lost so much insect life between the 1970s and today? It's hard to imagine gardeners using more insecticide now than then, especially given that so-called organic gardening is flavour of the minute amongst the chattering classes (so amongst most people rich enough to have a big enough garden to matter). And the study almost seems to be claiming that people should not be leaving seed out in the garden for sparrows (and hence for birds, period, because once you feed one, you feed them all), since that is allegedly not as "healthy" as spiders. But that seems ridiculous (but you never know). Are more people feeding seed to birds now than in the 1970s? Is there no relationship to climate change? Etc.

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