What I have noticed during this extreme cold spell is the lack of bird song, and bird life in general. It was the exception of hearing a few birds chittering this morning that struck me; normally, it's like an airport outside y flat window; constant take off, landings and plenty of bird song.

It's not only the abrupt cessation of bird-song that's marking the sharpness of the weather, there's clear evidence of inter-species conflict for food. A friend told me yesterday how he'd watched blackbirds squaring up to pigeons in his back garden.