• Vincent

I just spent a lovely week on Sardinia. The recently split Mediterranean Flycatcher (Muscicapa tyrrhenica tyrrhenica) is pleasantly common there.

It seems to occur in a much wider range of habitats than Spotted Fly in NW Europe. From macchia to hill forests and from quiet farmland with scattered trees to village gardens: they seemed to be everywhere below the tree line.    

They differ from Spotted on plumage, biometrics and genetics (see Viganò and Corso 2015). I indeed had the impression that on average they were paler and less spotted below, but note that some were more marked than others, while on the other hand less well-marked Spotted Flycatchers can be found in NW Europe.

For now I reckon we are still a long way off to identify a potential vagrant in NW Europe with certainty.

The "Spanish" Med island ssp. balearica seems to differ a tod more from Spotted, with a pale speckled crown. Check out Marc Illa's wonderful website for more details and an instructive pic.

The birds on Sardinia were very vocal:


A quick comparison with five recordings of Spotted Fly on xeno-canto slightly suggests that the calls I recorded are on average slightly higher pitched, though I have no clue about individual variation (and with high pitched calls the quality of the recordings certainly plays a role), so it might be nothing at all.  

My recording of the alarm call is rather poor, but I couldn't find any obvious differences. I never heard its song. 

Word is on the street that Viganò and Corso are about to finish a new piece on this taxon that includes calls. Something interesting to look forward to, cause I hope to learn a bit more about these birds! 

#MediterraneanFlycatcher #Sardinia #birdidentification

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  • Vincent

First proof that it's the nominate subspecies of Hume's Leaf Warbler that reaches Europe.

Aerobics, the final countdown and warbler taxonomy

Back in the 80s, Hume's Leaf Warbler was still considered a ssp. of Yellow-browed Warbler. Since then not only our hair fashion and taste in music has improved, but also our insights in leaf warbler taxonomy. There are significant genetic, morphological and acoustic differences between the two and acoustic experiments in overlapping breeding ranges show that these species basically ignore each other (Irwin et al 2001). So: different species. No discussion.

But what about Hume's Warbler ssp?

But Hume's Leaf Warbler has two ssp: humei and mandellii. These two ssp. also differ genetically, morphologically and acoustically. Whether you call them species or subspecies, depends a bit on the species concept you prefer (Irwin 2001). The nominate breeds in mountains in the northern part of the Indian Subcontinent, Central Asia, S Russia and Mongolia, while Mandelli's Leaf Warbler has an isolated range in C China, 1500 km away from the nearest breeding Hume's. Hume's winters around the Indian Subcontinent, Mandelli's in SE Asia. Mandelli's is somewhat browner, with a greyer cap, it usually has no upper wingbar and it often has some yellow in the eyebrow and on the underparts (Clement 2017). The genetic distance between the two ssp. is much smaller than between Hume's and Yellow-browed. Hume's and Mandelli's have two song types: a "double note" and something vaguely reminiscent of a squeaky V-belt. The double note slightly differs since it's a bit higher pitched in Mandelli's. Mandelli's als has a higher pitched call. Acoustic experiments however show that Hume's and Mandelli's respond to each other's vocalisations (Irwin et al 2001).

The acoustic experiments are enough reason to regard them as ssp. and as far as I know not a single world list has split them. It's likely that they are in the process of becoming separate species, but are just not there yet.

Figure 2. Genetic variation between Yellow-browed, Hume's Leaf and Mandelli's Leaf Warbler, including the bird ringed in Meijendel.

So what about the vagrants in Europe?

Due to their respective ranges, it's of course the nominate ssp. that most likely shows up in Europe. Both the plumages and calls of Dutch birds I checked also imply that. But I think it has never really been sorted out. So Peter de Knijff analysed some feathers I collected of the bird I trapped on 7 November 2017 in Meijendel, Wassenaar, the Netherlands (the bird on top of this post). The analysis proofs that, as expected, it was indeed a humei. This is the first genetic proof of this subspecies in Europe (Martin Collinson in litt). See figure 2 (made by Peter de Knijff).

No surprises here, but at least we have now established with certainty that humei is the default taxon in Europe.

More details will be published in a Hume's Leaf Warbler overview in Dutch Birding magazine later this year.

Acknowledgements

Martin Collinson confirmed no other humei has been genetically tested in Europe before. Peter de Knijff is once more thanked for his genetic analyses. Peter made figure 2.

References

Irwin, D E , P Alström, U Olsson & Z M Benowitz-Fredericks 2001. Cryptic species in the genus Phylloscopus (Old World leaf warblers). Ibis 143: 233-247

Clement, P 2017. Hume's Leaf-warbler (Phylloscopus humei). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona.

#geneticanalyses #HumesLeafWarbler

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  • Vincent

Probable Russian Common Gull, 5 February 2012, Meijendel, Wassenaar, the Netherlands

I don't like using measurements as a diagnostic feature to ID sexes or subspecies. Last week was no exception.

After another mild winter, an unusual late cold spell hit the country early March. Temperatures dropped to minus 8 C, combined with a 7 Bft easterly. At the very end of winter... that's just killing. Litterally for the birds if they don't start moving. 

Rinse and I trap four Common Gulls in Meijendel, Zuid-Holland, the Netherlands on 1 March. One large bird is of particular interest since it has a wing length of 398 mm (left) and 399 mm (right).

Based on Malling Olsen & Larsson (2004), Demongin (2016) and Baker (2017) – that together combine many sources – everything above 395mm should be diagnostic for Russian Common Gull heinei. The tarsus (54,2 mm) is well above the average for Common Gull (50,8 mm), all other measurements fit both subspecies well.

But the bird just didn't look right. Or not classic anyway – as far as classic is appropriate for these subspecies. It had a speckled head, and not the desired whitish head with a speckled scarf (reminiscent of a Caspian Gull). The iris was very dark and the bill and legs were dull yellowish to greenish, instead of the prefered plain yellow.

(sorry for the crappy shots; they were made around dawn with my phone)

I also noticed another feature that was completely wrong for Russian: no black band on the 5th primary. 

Though apparently this is not a heinei, based on the much smaller wing lengths of breeding males in e.g. Great Britain (Baker, 2017), I however think it's likely that these large, wintering birds have an eastern origin.

Adriaens & Gibbins (2016) published an impressive Dutch Birding ID issue on the matter:

Just for the fun of it I scored the bird on the 15 features they present. On seven points the bird showed features that the majority of heinei also shows (note that quite a few of these are also majority features for canus), five features are minority features (and these fit canus much better),  and in two it was unclear. The final one - the lack of a black band on p5 - is an absolute no go.  

So apparently it's true: size doesn't matter!

We trapped an apparent canus with with a wing length more associated with heinei.   

The 2012 birds

In 2012 we trapped several likelier heinei candidates (also see pic on top of this post). I didn't photograph the wing well enough to asses all features in Adriaens & Gibbons (2016) properly (how was I to know what exactly to look for at the time!) but out of the 11 features that can be checked, the bird on the photograph scores 10 majority features for Russian. Only the band on the bill could have been clearer. Also note the less intense speckling on the head, the scarf, the medium pale iris and the bright yellow bill and legs.  

And yes, it has a solid black band on p5. The bill length was also in the range of what's considered diagnostic for heinei

How was I to know back then that I should have photographed all tongues and black wedges?​ Check the solid W-shaped black band on p5.

After a few birds in 2013 (no heinei candidates), it had been five long years since I trapped some Common Gulls. Let's hope it won't take another five!

References

Adriaens, P. & C. Gibbins. Identification of the Larus canus complex. Dutch Birding 38:1

Baker, J. 2017. Identification of European Non-Passerines. BTO, Thetford.

Demongin, L. 2016. Identification guide to birds in the hand. Beauregard-Vendon.

Malling Olsen, K. & H. Larsson 2004. Gulls of Europe, Asia and North America. Christopher Helm, London

#CommonGull #heinei

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