Blackcaps and bird feeders

Feeding goes a long way
Blackcap movements (from Time to Fly)
Blackcaps (green) leave Britain in the autumn to winter around the Mediterranean, returning in spring (cream). A few birds (orange) pass through on migration. Some birds (yellow) now winter in Britain and Ireland - the focus of this study. 

We usually think of Blackcaps as being spring and summer visitors to our shores, enlivening these seasons with their rich, piping melodies from scrubby thickets. For most garden birdwatchers, however, Blackcaps are birds of wintertime, arriving at feeding stations around the turn of the year when natural fruits have been depleted.

But for a few waifs and strays, these winter visitors are not the same birds that nested in the UK earlier in the year, these having departed south for warmer climes during late summer. Instead, they are breeding birds from central Europe, which turn to our gardens in search of bird food.

Numbers of these winter wanderers are increasing. When once Blackcaps spending the winter with us would probably have died, our growing fondness for feeding birds in gardens, coupled with our warming winter climate, is helping them to survive.

Higher housing densities in urban and suburban areas mean that food supplement availability is greater than in rural habitats, and temperatures are also that bit higher due to the ‘urban heat island’ effect. As a result, Blackcaps push right into our towns and cities over winter to enjoy the benefits.

Where Blackcaps spend the winter is important. Research shows that those wintering here tend to pair up together when they return to their nesting grounds in central Europe in the spring. Similarly, those Blackcaps that spend the winter in Iberia and North Africa – this species’ traditional wintering grounds – also tend to pair up together when they arrive back in central Europe to nest.

Blackcap breeding populations are, therefore, separating because of differences in wintering locations, and these differences appear to be influenced by food provided in our gardens. We now know, thanks to research published in 2015 which shows that supplementary feeding has affected Blackcap migration.

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