The last decades have seen a change in the distribution of many species as a result of climate warming. If you read the abstract of this recent article you will see this affecting many different terrestrial organisms. In the bird world, a typical example of range shift towards the north is that of the Cetti's Warbler. Some years ago, the species featured in headlines like "Mediterranean Songbird Spreads", but today the Cetti's Warbler is no longer just a bird of the Mediterranean, but British in its own right - resident in many of the Southern counties of England. Cetti's Warblers are slowly (or rapidly, depending on your timescale) advancing north as can be seen in the sequenced maps from the old Breeding Atlases here.
On 2nd of October 2011 ringers from the Natural History Society of Northumbria Ringing Group controlled a Cetti's Warbler. This is, as far as we are aware, the first time that a Cetti's Wabler has been captured by ringers in this county. The bird in question GBT X586751 had been ringed as a 3J the 26 June 2010 by Tees Ringing Group, just a few kilometres south in Billingham, Cleveland. This ringing event is important because it could be the first evidence from ringing of the species moving north and conquering a new county. Perhaps in a few years the Cetti's Warbler will be an established BIRD OF NORTHUMBERLAND! We can't wait to find out from the next Atlas just how far Cetti's Warblers has spread.
To read an article about Cetti's Warbler and ringing data go here.
(Photo of a Cetti's Wabler in the hand by Dawn Balmer)