• Vincent

Tristis: not always a peep show


pics © Marijn van Oss & Jorrit Vlot sound © Thijs Fijen

Earlier I wrote about Siberian Chiffchaffs with common Chiffchaff calls (here). That bird (mostly) looked like a Siberian Chiffchaff, and after analyses it indeed showed Siberian mtDNA - but in the field didn't utter the characteristic

peep.

No, it called like a Common Chiffchaff!

Now the following bird, observed on Vlieland on 25 October by Thijs Fijen and his mates Marijn van Oss and Jorrit Vlot, could very well be a similarly confusing - but highly interesting - bird.

This was a field observation so no DNA was obtained, but even though the bird is half hidden, and it's pretty dark, the pics absolutely give a tristis feel. These guys are are keen on identifying difficult birds, and based on plumage it sure looked like a bonafide tristis to them.

But here are the calls the bird uttered:


(if sound app doesn't work, use this link)

Not even remotely close to a Siberian. So yet another intriguing bird!

In the mean time our DNA work on chiffchaffs continues. At the momente we're collecting our final feather samples. We now have over 800, from several countries. Peter de Knijff and myself hope to publish the Dutch mtDNA data in 2019. A full gene analyses of all tristis (to see if we get birds with mixed genes; the bird with the 'wrong' call will be super interesting to test) will take a bit longer.

Thanks for the pics and sound recording, Thijs, Marijn & Jorrit!

#birdidentification #CommonChiffchaff #SiberianChiffchaff #calls #tristis

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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