Voles galore?

It is looking as if the 2014 Barn Owl breeding season, nationally, was perhaps the best ever recorded (following an atrocious year in 2013, which was the worst since 1958). The breeding success of Barn Owls is very closely linked to vole abundance, and vole populations are cyclical, fluctuating widely over a 3-4 year period. The reasons for this fluctuation are something of an enigma (further reading). It has been estimated that in a bumper year, a hectare of suitable habitat can hold as many as 20,000 voles; in poor years the same area may support literally a handful. Barn Owls are stimulated into breeding condition by prey availability – the more prey there is, the earlier they lay their eggs, and this provides the opportunity for second clutches in good vole years, as was seen in Gloucestershire for the first time last year. Early indications are that 2015 may also be a good vole year..

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