Firstly, a happy and productive New Year to my handful of regular readers. My last day’s ringing at SML for 2019 turned out to be the least productive session ever with just one new bird and six re-traps caught in four hours with 90 metres of net erected. A minor consolation came in the form of a UK control Chiffchaff but everything was hard work. The weather was particularly gloomy with enough moisture in the air to condense on the nets requiring more frequent rounds than usual. The wind, although light, was from the southwest, the least favourable direction for trapping around the sewage works in winter and the ground was saturated making progress between and along the net rides slow and hazardous. Even my lightweight Daihatsu 4×4 with the diff-lock on struggled to find enough grip to get me and the ringing gear on-site.
I tend not to visit on days like this as experience has shown that most Chiffs are present when it’s calm and sunny, which encourages chironomid midges to swarm around the sewage works. It does make me wonder where the birds go when the weather is less favourable. Perhaps they feed in woodland and large private gardens further up the valley on days like this. Ringing in previous winters has shown the minimum population at SML to be around 90 birds with estimates, made using capture/recapture models, suggesting that the true figure could lie between 188 and 227. That’s a lot of disappearing birds!
Crops of photos taken recently at South Milton Ley by Richie Moore, published on the Devon Birds’ website and reproduced here, clearly show the importance of chironomid swarms to wintering insectivores when the sun is out. Reassuringly, all the birds have rings on!