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start:life_sciences:biology:sparrow_decline

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Sparrow decline

Large declines of urban and suburban house sparrow (Passer domesticus) populations have been recorded in many towns and cities across Europe. In London, sparrow numbers fell by 60% between 1994 and 2004. The cause(s) of the decline is still not resolved.

Prominent theories include:

• Reduction in the availability of favoured food, either for adults or chicks or both.
• Increased levels of pollution.
• Loss of suitable nesting sites.
• Increased prevalence of disease.
• Increased levels of predation.

with other suggestions such as:

• Mobile phone mast radiation.
• Fibreglass loft insulation.

To date, no scientific research projects have proven any of the theories - either alone or in combination with others.

Since 2013 there are reports that the rate of decline has stabilised - recent anecdotal evidence suggests that in some areas (of the UK) the numbers may be increasing again.

More details here at the British Trust for Ornithology


Note: In 2000, UK newspaper The Independent offered a prize of £5,000 for a proper scientific explanation of the house sparrow's widespread disappearance - the prize remains unclaimed.

Also see: Cuckoo decline

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