Predation and songbird declines:
what’s the evidence?
A study published in The Auk, in 2010, argued that increasing numbers of, and predation by, sparrowhawks since the 1970s “may be sufficient explanation for” the decline of house sparrows.
Researchers from the BTO carried out a more extensive study into the impact of a suite of predators on 29 species, mainly songbirds. They found no effect on 22 species, with the possible impact of sparrowhawks on bullfinches, reed buntings and tree sparrows “most worthy of further investigation”.
Kestrels and grey squirrels were also found to have a negative effect on nuthatches and tree sparrows, and wrens and blackbirds ( above), respectively.
Research published in the Journal of Applied Ecology in 2013 found the presence of domestic cats and grey squirrels caused blackbirds to reduce provisioning of their chicks by up to a third.