• Vincent

Primary moult of a Dutch Bonxie

There are probably not too many primary moult scores for Great Skuas from Holland. But I've got one now!

Since we usually only see them on migration, at a fair distance, and immatures are in the majority, it was quite a privilege to study an adult at close range (upper pic: Sharon Lexmond/ De Wulp).

This bird was taken into care at bird hospital De Wulp in September. Just note how bleached and worn it was! The 'pied' plumage easily gives it away as an adult. It was skin and bones, but 6 weeks later it's doing well.

Rinse and I ringed it before it was released back into the wild. This must be one of the strongest birds I ever handled. What a monster! I've been attacked by them on St. Kilda (pic below) before, but only now I understand why they are capable of killing birds the size of a Lesser Black-backed Gull...

The patient was well taken care of by the ladies. So well, that it started moulting primaries in captivity. An energy consuming process that strongly indicates that the bird left its physical problems behind. And the good thing is: this is right on schedule for the species.

The five outer primaries (RED) are still old, then there are two growing ones (ORANGE), and finally the inner three (GREEN) are new and fully grown (primary score: 0+0+0+0+0+2+3+5+5+5=20). Note the difference in shape and wear between the old and new ones!

The bird was a bit wet from the bassin, so it looks a somewhat scruffy, but just note how fresh and black the new and growing inner primaries are, and how worn and bleached the outer ones:

I probably won't get to see a moulting Bonxie at close range anytime soon, so this was a moment to cherish.

#GreatSkua #primarymoult #ageing #moult

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