Friday, 3 November 2017

Marsworth 27th and 29th October - Faulty feathers

Two very different days ringing just two days apart.
Friday was beautiful weather, sunny and calm, so I took the opportunity to get out and tried a new net near the nyger seed feeder that I put out last week. Nothing seems to have found the feeder yet but it is still a nice position for a net at the edge of the trees in the low willow scrub. The Redwing tape brought in a few individuals and I also caught the first Redpolls of the year; we generally only catch Redpolls in October and November when they are passing through. The new net also caught a new Great Spotted Woodpecker with quite dramatic fault bars across his flight feathers. Fault bars are  caused by an interruption in nutrition while the feathers are growing and when the fault lines up across the feathers like this they indicate that the feathers all grew simultaneously. Fault bars are not unusual in juvenile birds.
Great Spotted Woodpecker with pale fault bars across unmoulted secondaries and primary coverts.
There were some interesting fault bars to be seen on other birds as well as the woodpecker. An adult Blue Tit had a fault bar across three of his tail feathers, it looked as though he had replaced his tail as part of the normal post-breeding moult and then had to replace three feathers from some accidental loss. Why the replaced feathers had a fault bar is curious - perhaps he had a near miss with a sparrowhawk and had been below par in his foraging for a few days? In any case it was a good example of how a fault bar can be present on adult type feathers.

4M Blue Tit with fault bar across three feathers
I also caught a new control Cetti's Warbler that was ringed at Rutland Water in June as a 3J. This bird had very poor feathers. The primaries were extremely tatty and the tail had some of the feather tips completely broken off apparently caused by a combination of fault bars and feather mites. Five of the feathers looked as though they had already been replaced and it will be interesting if we retrap this bird to see if she carries on replacing tail feathers as necessary.

Juvenile Cetti's Warbler from Rutland Water
Thankfully the hornets have largely disappeared now that there has been some colder weather, I spotted one later on in the morning when the temperature rose which hurried me into taking the nets down. I have had enough of cutting nets to release them!

After the pleasant day on Friday the weather on Sunday was very different. The forecast had been for breezy weather but when Gabor, Chris and I got there at 06:30 it was more like 25mph. We stood around for a while trying to decide whether to bother but the wind started to drop so we put a few nets up in the more sheltered areas. We managed to get five nets up in the end and caught Goldcrests, two more Redpolls and four Chiffchaff. We tried a hopeful tape lure of Hawfinch call following numerous sightings of Hawfinch passing over in the last week but no luck. A few Goldcrests, a Bullfinch and a Long-tail Tit flock of mainly retraps brought the total for the day up to 33.


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