A Glut of Robins: Thursday, 6th August 2020

A quite remarkable session at the Firs this morning. The forecast when I went to bed last night was for it to be dry, warm and sunny. By the time I got to site, it was dull, miserable and damp: incredibly humid. Although, apart from two brief showers, it never properly rained, it was like working within a light mist all morning. Everything got damp and by the time I had erected my nets ( 3 x 18m in one run and 4 x 18m in the other) down the central glade I was soaking wet, mainly from the humidity.

My first round was a good catch of 14 birds: 7 of them were Robins. That is how it continued throughout the morning: with Robin appearing in virtually every catch. I finished the day with 20 Robins out of a catch of 52 birds. The previous largest haul of this species at any of my sites was 12 at Somerford Common and also in the Firs, both in July 2018. It has definitely been a good year for them: we caught 10 at Somerford Common on Saturday.

The catch for the day was: Great Spotted Woodpecker 1(1); Blue Tit 5(2); Great Tit 6; Wren 4(1); Robin 17(3); Song Thrush 1; Blackbird 2; Blackcap 3(3); Chiffchaff 1; Bullfinch 2. Totals: 42 birds ringed from 10 species, 10 birds retrapped from 5 species, making 52 birds processed from 10 species.

43 of the 52 birds were juveniles: Great Spotted Woodpecker 1; Blue Tit 4; Great Tit 5; Wren 5; Robin 20; Song Thrush 1; Blackbird 2; Blackcap 3; Chiffchaff 1; Bullfinch 1. There was at least 1 juvenile from each of the species in the catch.

The 20 Robins were all juvenile birds, representing the three post-fledging stages: still in full juvenile plumage; undergoing post-fledging moult and completed post-fledging moult. I think this indicates that some Robin pairs might have managed to produce 3 broods this year.

What I thought was an oddity amongst the juveniles happened with a group of 4 Great Tits, one was an adult female undergoing post-breeding moult, as one would expect, but the other three were juveniles undergoing their post-fledging moult and all three were moulting their tail feathers. I cannot say that I have ever noticed this before in juvenile Great Tits. However, according to the two moult Bibles (Jenni & Winckler and Ginn & Melville) a full moult of the retrices is part of the Great Tit’s post-juvenile moult strategy. What can I say? I have processed over 2,000 Great Tits, including 830 juveniles, and this is the first time that I can definitely recall seeing juveniles moulting their tails.

The highlights, apart from the glut of Robins, were my second juvenile Bullfinch and Great Spotted Woodpecker of the year:

With heavy rain forecast from 11:00 I closed and took down the 3 net run at 10:30. Processed the birds that remained and then took down the 4 net run at 11:00. The forecast rain never arrived! Still, a very satisfying woodland session. My only disappointments: despite hearing them around the reserve all morning, I didn’t manage to catch any Nuthatch or Marsh Tit. Never mind, lures will be available soon.

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