03 September 2011

Waiting for the kids to leave home

Over 36,000 Reed Warblers were ringed in the UK during 2010, so what was interesting about the seven caught at a site in south Norfolk on Thursday?

During the summer of 2011, a team of BTO staff, collectively known as The Swamp Things (AKA Dave Leech, Lee Barber, Rachael Portnall, Mike Toms and Jez Blackburn), decided that the best way to spend their free time would be to slip into a pair chest waders and wander the reedbeds of Norfolk. Why, you ask? A good question, especially when the temperature rises into the high twenties and the horseflies are hungry, but there was method in their madness as there really is no other way to collect data on the nesting success of Reed Warblers.

So, when the warblers arrived back from Africa in April, The Swamp Things sprang into action, catching and ringing the adults, finding their nests and ringing the chicks. The first full clutch of eggs was recorded on the 8th May, and the last nestling was ringed on the 12th August, by which time several of the team were looking considerably sleeker and, at least from the shoulders up, more tanned. In the intervening three months, they monitored 257 nests and ringed 596 nestlings. An added bonus was provided by the 12 nests parasitized by Cuckoos, of which at least seven were thought to have fledged (and by now have presumably joined Clement , Martin, Caspar, Lyster, and Chris on their wintering grounds).

The seven birds mentioned at the top of this posting were all ringed as chicks in the nest between the 8th and the 30th July and are still finishing their moult and building up their fat reserves. By adding this information to the other recaptures of ringed nestlings, the team will be able to learn a lot more about the behaviour of the youngsters when they reach independence and prepare for their first ever migration, an incredibly important, yet seldom studied, period in their lives.

Thanks to Dave Leech for this post.

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