OUR garden has played host to at least seven blackbirds over the winter with, at times, three males picking up scraps beneath the bird feeders and up to four females, including the bird shown with a distinctive white flash in the crown.

This bird is of particular interest because individual birds are usually impossible to identify. This female has been around our garden for the last two summers making her at least two and a half years old so a mature and experienced bird and parent to a number of offspring which have reached adulthood.

As shown by this female, many of our winter blackbirds are local and studies show that the majority of British blackbirds spend their lives within a mile or two of where they were born. Their numbers are swelled during winter when we get a big influx of birds from Scandinavia and Eastern Europe.

During the winter months there is little aggression between them and they will even roost communally but by the end of February the non-aggression pacts break down as males begin to define their territories and the lawns along our street witness male posturing and chasing while many roofs and TV aerials have singing males.

The abundance of blackbirds is in marked contrast to the winter paucity of song thrushes for, although many are said to remain in the same area year round with most establishing winter territories, they vanish from our garden and the adjacent woods. A single bird appeared on the 9th February but I have seen none since. They are sensitive to hard weather when frozen ground restricts their access to worms and hibernating snails are harder to find and I suspect that ours move south, perhaps ending up as far away as France and Spain.

The UK song thrush population is only a quarter of that of the blackbird and sadly they have declined by at least 50% over the last 25 years, with the fall more pronounced in farmland where loss of hedgerows and wet ditches has removed nesting and feeding sites. Research has shown that, in intensively farmed land, song thrushes make fewer nesting attempts per year and that fewer fledglings survive once out of the nest due to a lack of earthworms and snails.

Every spring I look for their return when they use our silver birches as song posts, like the blackbirds singing until it is almost dark and leaving broken snail shells littering the patio.

Gardens are these days becoming a last refuge for many species and with garden pesticide use becoming ever more intensive perhaps gardeners need to ask which garden chemicals they are justified in using. Without the songs of blackbirds and song thrushes it would be a silent Spring indeed.

l www.wharfedale-nats.org.uk