Ageing Leach's Storm Petrel

Every time I get to see one of those blackish, passerine sized seabirds during gale force winds, my heart misses a beat or two. I just can't grasp how such a small bird conquers the elements with such ease.

But for a Dutch guy it's rather unusual to have a truly decent look at a Leach's Storm Petrel. Basically we only see them in the unfavourable conditions of a heavy autumn storm, when they pass by at quite a distance, in the mean time disappearing behind the waves half of the time. Spectacular, but it doesn't allow any plumage studies!

But for the first time in my life I had a more than close inspection. The lovely people at bird hospital De Wulp (The Hague) always inform me when they have an unusual bird inside. Unfortunately this Leach's died over night. But being dead and all, I did have the opportunity to examine the corpse.

Was I able to age it? Based on Baker (2016) and Demongin (2016) it's a 1st cy. Furthermore, this very nice BB article can be found online.

The blackish primaries and secondaries were all of the same generation and rather fresh. Note how pointed the outer primary is. In adults they should be worn and bleached in autumn, there should be some moult visible in October and the outer primaries should be more rounded.

There are several other clues...

...like the colour (grey instead of brownish) of the greater coverts. Several even have white edges.

Perhaps most striking are the white edges on the tertials.

The buffy spots on the inner webs of the primary coverts were very striking, too. I had no idea Leach's had these spots! I have no clue whether it's age related, or not (if you do know, please let me know).

It was an unexpected feature that I think is nice to share.

What a shame this little gem died, I would have loved to put a ring on it and send it to the southern hemisphere to winter!

#ageing #LeachsStormPetrel

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

Warbler update!

I've added another file in the chiffchaff corner. Is the bird in the post an Iberian Chiffchaff, or not?

Furthermore I've now finished the piece on the status and (temporal) distribution of Greenish Warbler

If you have any questions or remarks, don't hesitate to contact me.