Sunday, April 28, 2013

More ringing notes

Let's see some things about Scops Owls (Otus scops) in spring...

- Juveniles make a partial postjuvenile moult that involves body and median and lesser coverts, leaving unmoulted all primaries, secondaries, tertials and rectrices. Then, in spring, 2cy birds show remiges quite worn, discoloured. Central rectrices are also a good criteria, because they are still juvenile-type and is quite different than the adult-type.
- Adults make a complete postnuptial moult, started in breeding areas in later summer, suspended and finished in wintering quarters. In spring, they show fresh plumage and adult-type rectrices.

Sometimes, judge the wear of remiges could be difficult, specially if you are not used to ring Scops. You should search for good light and try to observe properly all feathers. At least for me, shape and pattern of wing and tail feathers is the best criteria. Specially easy to see in rectrices and secondaries, adult-type feathers have squared and not pointed tips, and white bars on the external part of remiges if also more squared. Black lines going around white bars in rectrices are bigger in adults.

Sorry for the differents lights... but check tips of secondaries. In the first photo, tips are pointed and all remiges are quite discolored (2cy bird, EURING 5). In the second one, feathers are freash and secondaries show rounded-squared tips (EURING 6).
In the first photo you can see the typical juvenile-type rectrices, with an irregular white bars and a very narrow black line. Tips are pointed and shows some wear. (2cy bird, EURING 5). In the photo below, tips are more rounded and black line is a little bit bigger. White bars are well-marked. (EURING 6)

SEXING is another thing that also could be interesting. No plumage differences are discovered, but it seems that the P8 (ascendantly) measure could be quite reliable: birds with P8 > 124 mm could be sexed as females.


It's Woodpigeon's time!!
I think they are really fun birds from a ringer's point of view. Woodpigeons make one of these 'complete postjuvenile moults' that is hardly never finished. So, not a really 'complete moult'!  As other pigeons, they do a 'slow' mould, that go on during some months. Then, is easy to catch a bird moulting primaries, in any month.

1st winter birds usually leave unmoulted some secundaries and maybe some other feathers. Juvenile feathers have a ochre border line on the tip, and this feature can be very useful in spring for 2cy birds. They should have some juveniles secondaries and usually some coverts too.

3cy birds in spring are  also recognisable but more difficult. In his second 'complete moult', they could leave unmoulted some secondaries again or do an authentic complete moult. So, in spring, a bird showing 3 generations in secondaries, one of them very worn (probable still juvenile feathers), should be 3cy (EURING 7).  You must also remind that they make strange moults, and can leave unmoulted a primary until the 3rd year, etc.

My bird was quite interesting. It showed 2 generations on secondaries, any retained juvenile covert, active moult in primaries and no old rectrices.

I aged it as a 3+cy (EURING 6). With only two secondaries generations, and no obviously juvenile feathers, the bird could be an older bird that simply left unmoulted some secondaries. Or maybe an authentic 3cy that replaced his juvenile feathers... In this cases, we should look for the minimum age possible, in order to not remove possibilities.

If you are interested, you should visit these links:
- Some Stephen Menzie's notes: here, here and here.
- David Norman's page
- Javier Blasco's excellent work, in PDF.

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