Friday, 9 December 2011

Recent recoveries

The most recent batches of recoveries from the BTO are dominated by Barn Owls (21 of 27). About three quarters of these were female, which is to be expected as we mostly just catch the females in boxes in the breeding season, with the males roosting elsewhere. Usually, when we catch new breeding birds, especially females, they are first summer birds, but this year there were: 4 first summer, 3 second, 2 third, 1 fourth & 1 fifth summer females. Some of these weren't in the same box last year as there were different females in them then and they would have bred elsewhere since fledging. This is uncommon and I put it down to the bad snow and cold we had last winter, in which birds presumably moved off their winter territories and/or lost their mates, went in search of food and stayed put wherever they ended up. Of the 5 males controlled, one was 5 and the other 6 years old. The Barn Owl movements varied between 4 and 93 km, with the median distance being 15 km. Most recoveries were movements within our study area (south Notts and Vale of Belvoir), but there were also 3 from Lincs, 1 from Cambridgeshire & 5 year old male from South Yorks.

Aside from the BOs, we also had a Jackdaw pullus from Kersall that hit an overhead wire near Southwell 12 km away at one of the farms where we have boxes. A typical Kestrel recovery is one found dead in a barn in its first winter. So, no surprise when 2009 Kestrel chick from Brackenhurst was found 5 km away in a barn near Southwell in September. Of more interest was another 2009 Kestrel chick from Bunny that was caught in a Barn Owl box with chicks near Bottesford; a movement of 24 km. There are very few live recoveries of Kestrel and this adds to our knowledge on their dispersal. In addition, there were also two local recoveries of Long-tailed Tit and a Yellowhammer on the Brackenhurst Campus.

Jim

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