Letter: Owls on the increase and nightingales that sing in Berkeley Square

Sir: With reference to the declining numbers of barn owls (Science, 8 November), unlike the peregrine and the sparrow hawk, there is little evidence to suggest that pesticide poisoning is a contributing factor in reducing barn owl population in the UK. The main factor has been severe weather conditions, which have reduced the numbers of small mammals that are the owl's main food source.

Fortunately, this beautiful creature's numbers are now increasing, and often it can be seen hunting over fields and meadows:

Alone and warming his five wits,

The white owl in the belfry sits.

(Tennyson)

Yours faithfully,

CHRIS BOSELEY

Atherton, Greater Manchester

(Photograph omitted)