15 January 2010

Blackcap in the snow

Blackcaps are a fascinating bird... As recently as the 1970s they were really scarce in winter, but things soon changed (read more). As they became more common in winter the temptation was to think of these as 'our' birds managing to stay the winter instead of migrating. But ringing (and stable isotope studies) showed this to be far from the truth and these were actually birds from northern Europe migrating west instead of south for the winter. Presumably as more and more of these birds survived our milder winters the rogue gene for this new migration heading became more prevalent.

So it's interesting to think of the possible impact of this current harsh winter on these birds. Will it wipe them out, leaving them as a scarce winter visitor again???

One bird in particular seems to be doing pretty well though. We received details of a colour-ringed bird in a garden in Reading in early January and after a bit of digging tracked it down. X170529 was ringed on 3 January 2009 at near Tipton St. John in Devon.

Ian Stanbridge, who ringed the bird, catches winter Blackcaps by feeding them fat, and has so far ringed 41 birds since winter 2001/02. Some are then retrapped and one bird ringed in January 2002 has been recaught in March 2006 and again in February 2008, showing how faithful these birds can be to their wintering areas.

Thanks to Tim Ball for getting in touch about this bird, to Roger Stansfield for the pics and to Ian for sending us details of his work.

1 comment:

  1. If you can take the science see: Isolation and phenotypic divergence in sympatry along a migratory divide. Current Biology 19, 1-5, December 29, 2009 - which explains all about Blackcaps