• Vincent

The look-alike that turned out to be a tristis after all. Maybe. I think so. Right?

Right. Chiffchaffs never stop to amaze me. But I now feel we're really getting somewhere.

Only very recently Peter de Knijff and I wrote something about Siberian Chiffchaff look-alikes on this site. The upper bird in that little web article looked like a tristis, but IMHO it was not an exact copy. Something looked off. So I ringed it as a Common Chiffchaff, without specifying the ssp.

More significant is that it called dozens of times, just before I released it. And it called like a Common Chiffchaff collybita/ abietinus.

The spectogram also shows a perfect match for Common, with an upward inflected call:

I did ask Peter to look carefully at the feather material I collected. Now Peter's mtDNA analyses came in: tristis. Yes, this bird with a hueet call shows tristis mtDNA!

Fairly recently they had a similar case in the UK, see here (scroll a few pics down) and here.

In 2018 Peter and his students will run a second test on all tristis we've trapped at five sites over the past five years. In this second test we'll try to figure out if any introgression with abietinus can be found. This will hopefully give new insights into stray Siberian Chiffchaffs in NW Europe. And in this individual - hopefully!

To be continued!

(I will add this web post as a post scriptum to the afore mentioned web article about look-alikes).

#mtDNA #geneticanalyses #SiberianChiffchaff #CommonChiffchaff #tristi #abietinus

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Little Bunting
The most interesting thing about this chapter is the sexing of birds. This could be done on the basis of lateral crown stripe: a new feature for me. Because of overlap between adult females and young males, birds should first be aged. The authors emphasize that this is their vision, and not necessarily the final answer to this matter. I found one in the field in October (Figure 4-5) of which I took reasonable pictures. The very rounded tail feathers look adult, as do the tertials and large coverts. The lateral crown stripe appears to be jet black and is separated from other feathers, such as the greyer back of the head. The orange-red crown stripe really stands out. Conclusion: according to this book this must be an adult male! The deep brown-red cheek - a variable feature according to this book - also fits that. So it works then? Well… how useful this really is, remains the question: based on this book I would label two "females" in Shirihai & Svensson (p546 both top right and bottom right) as males! The caption of one of these even mentions "safely identified as a female" because it has a relatively dull plumage for an adult bird. But is also has a jet black, strongly separated lateral crown stripe! The bird at the bottom right even has a pretty deeply coloured cheek, which I would be happy to call a male. Is this due to different insights, and if so, who should I believe? Or am I not interpreting this correctly? In any case, it is fascinating!

© 2018 by Vincent van der Spek