The Blackcap in Catalonia

Common resident, winter visitor and passage migrant.

Best Sites: absent only from Ebro Delta and Steppes of Lleida.

It’s possible, just possible, that three blackcaps meeting in a southern English woodland during late September each comes from a different European population.  The first is from the native population, about to disembark for the Mediterranean, and possibly on to West Africa, for the winter. 

Although their range has changed very little since 1945, their numbers have increased twofold, a trend mimicked across several regions of Europe.  In part this has been due to an increase in suitable habitat, such as parks and gardens, through human activity but climate change has also contributed, with milder winters allowing blackcaps to steadily bring forward the start of their breeding season.

At the season’s end, and after building up fat reserves for a non-stop flight to Iberia, they are joined by an influx of birds from Scandinavia that are stopping off on their way to the same final wintering grounds.

Odd then to think that yet another population, from Germany and Austria, is on its way in the opposite direction.  In all, some three thousand birds now spend the winter in the UK, mainly in the midlands and the south, a far cry from the 1940’s when there were barely twenty reports annually.

These reports however do seem to suggest that the genetic disposition to migrate north has existed for a long time.  In what has historically proved to be an unsuitable environment though, natural selection has meant that these birds would normally die.

But milder winters, the planting of berry bushes to protect coastal areas and the British obsession with garden feeders has led to a far higher rate of survival.  These birds then, arriving back in their native breeding areas earlier and with more energy than their ‘southern’ counterparts, thrive still further and a whole new population is born that regards the UK as its wintering home.

Interestingly, the picture is further complicated by non-migratory populations in some parts of Iberia, France and NW Africa, and an eastern European population that winters in East Africa.