Tuesday, 16 February 2016

An unexpected recovery

As a general rule the more birds you ring of a particular species the greater the chance there is of one or more being recovered (found elsewhere) and larger species tend to have higher recovery rates than the smaller ones. While that is the way things average out over time at the national level it doesn't always work out that way in practice for individual ringers or ringing groups.

Last year I ringed 746 warblers at Billinge with the majority being Chiffchaffs and Willow Warblers with totals of 269 and 256 respectively and Blackcap came in third place with a respectable 173 ringed. Statistically there was a reasonable chance that one or more birds from those top 3 ringed species of warbler would have been recovered by now but, disappointingly, not a single one has been reported so far.

At the other end of the numbers scale I ring very few Sedge Warblers at Billinge as it is a dry habitat on the side of a hill with no Sedge Warbler breeding sites close by. They only occur as a very scarce passage migrant as a result and only 6 were ringed in 2015. All were caught in the autumn between 22nd July and 11th August with 5 being first year birds and 1 an adult. So when I received a recovery report for one of these Sedge Warblers from the BTO the other day it was more than a little unexpected, to say the least.

Sedge Warbler Z680292 was a first year bird ringed at Billinge on 07/08/2015 and was controlled 679 km SSE in Noyant, Soulaire-et-Bourg, Maine-et-Loire France on 15/08/2015. This is a fairly quick movement averaging at just under 85 km per day although it is likely that the bird covered the 679 km in a couple of overnight flights with a refuelling stop in between.

Not the bird in question but one of the other first year Sedge Warblers ringed at Billinge last autumn.
The vagaries of recoveries and recovery rates can be a frustration for ringers especially when you don't get any recoveries from ringing large numbers of a particular species but just occasionally things work out the other way, as in this case.

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