House sparrows have certainly become a rare sight in most of our cities. Twenty-five years ago they were so common that one would pass them on the street without a glance, or jeer at their song as just a tuneless string of chirps. Now the sound of a chirp in a city makes one prick one's ears up, and one tries hard to get a glimpse of the pert little cock bird with its cap and bib.

Yet they are still quite common in villages, and in many European cities. I was in Dresden recently, sitting on a restaurant terrace outdoors. There were sparrows hopping about my feet, sitting on the backs of chairs and even flitting on to tables. It was a familiar sight that I had completely forgotten. Even in New York you see them - dingy little specimens sitting on hoardings in Times Square. An American, as blasé about them now as we used to be, said to me: “Are you short of sparrows? You can take these back with pleasure.”

The RSPB has found what seems convincing evidence that in British cities they cannot find enough insect food for their young. Yet their decline remains something of a puzzle. After all, birds such as titmice, which feed their young on insects, still flourish in town parks and gardens.

I still think that they may have lost nesting sites. Buildings are better sealed than they used to be. When did you last see a hole in a house with some untidy straw sticking out of it?

Derwent May is The Times Nature Notes correspondent

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