March 14th 2022 – A Chiffchaff smorgasbord

Moulting Siberian Chiffchaff

A beautiful spring day, only let down by a lack of birds. Out of 20 trapped this morning just five were new and only one of these was a migrant. There was a real mixture of Chiffchaffs present, identified by their ring numbers, including returning local breeders, lingering wintering birds, and one particularly scruffy looking Siberian tristis. The weight of one of the wintering Chiffs had increased from a portly 8.7g at the end of January up to a colossal 11.2g today, the heaviest I have ever encountered. Anticipating a protest from the recording software, (correctly as it happens!) I had checked the weight on two sets of scales, both of which were calibrated last week. Blowing the bird’s breast feathers apart revealed that its belly was yellow with fat. If it doesn’t depart soon it won’t get off the ground!

The Siberian Chiffchaff, which was first trapped on 21st December 2021, had managed to avoid recapture until today and what a sorry looking specimen it was. As the snow doesn’t clear from most of their breeding range until well into May, these eastern birds have a delayed pre-breeding moult relative to western european birds and most winters one or two remain at South Milton Ley until late April before departing. Todays’ bird was moulting its head, body and tail feathers and won’t be winning any beauty contests until at least mid-April!

The same bird back in December 2021

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