Friday, 30 December 2011

Granby Longevity Records

The Granby cutting from the bridge. (PML)

The recent capture of an elderly female Yellowhammer got me wondering about what other old birds we have had at the Granby feeding station. The table shows the top ten species longevity records for the site and gives the national records for comparison.

They are pretty much as you might expect in that the oldest birds come from the biggest samples. For example 990 Yellowhammers have been ringed there over last 12 years, so it's perhaps not so surprising that a nigh on nine year old bird has been retrapped. The older Robin retraps are mostly males and, given their territoriality, they are perhaps more likely to be recaught in the spring as they are frequently retrapped. Whereas the Blackbird was only retrapped the once. Disappointingly we’ve had no sight or sound of Willow Tits this winter, but this three year old bird was trapped 14 times over three years. Of the 399 adult Tree Sparrows ringed, only four have been trapped in the following winter and P575873 is the only one caught beyond that. Also, none of the 91 Tree Sparrow pullus ringed in the vicinity have been caught at the feeders.


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