British Trust For Ornithology.

The British Trust For Ornithology has released results from a survey in 2012 indicating that the loss of breeding sites is hammering our songbird population and they are right - to an extent.
What of the increased numbers of domestic cats - most of which do not wear a collar with bell? What about the rise in the magpie population and corvidae in general? What about the proliferation of grey squirrels?