Tuesday, April 17, 2007

2006 Winners and Losers from CES

CES - constant effort site - is a ringing protocol, standardised from year to year, enabling the production of adult survival rates and breeding productivity to be calculated. Figures are produced both nationally and locally and here are the figures just released for the North West.
For adult numbers there was only one increase on the index (compared to 2005) and that was for Whitethroat up +58. Significant declines were noted for Blackcap (-10) Robin (-14) Great Tit (-15) Bullfinch (-16) and Blue Tit (-25). I find these figures to be a little strange as there has been on noticeable differences in adult Blue and Great Tit capture rates for Merseyside Ringing Group and, in fact, this year has been my best ever for the capture of Bullfinches.
Productivity produces another set of ups and downs. Chiffchaff (-21), Wren (-28) Dunnock (-21) and Cetti's Warbler (-62) all continue their declines; both in comparison to 2005 and also against the 1983-2005 average. Blue Tit (+67) is the biggest climber, followed by Great Tit (+32) and then Reed Warbler, Sedge Warbler and Blackbird, all with increases in the twenties.
The 2005 increase in Greenfinches appears to have slowed and the decrease in Reed Buntings not reaching significance this year.

The map shows the location of ringers in the NW, by address not ringing site (red dots), and sites registered for CES (grey dots)

A free copy of the most recent CES News can be found at: http://www.bto.org/ringing/ringinfo/ces/ces_new_index.htm

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