Vocalisations vs. Appearence in a tricky Leaf warbler

29 04 2015

“If it has more than three chords, it’s Jazz”

– Lou Reed

It was a boring spring. Despite the good numbers of Pallid harrier and Great snipe registered mainly in the Northeastern Catalan coast, the best I had seen in Barcelona area was a “Mediterranean” spotted flycatcher Muscicapa s. balearica/tyrrhenica. Sadly, the bird went away without me being able to take a photo of the underwing.

belearica

Yesterday felt just like another random day: some Willow warblers, some Pied flycatchers, a sudden Redstart… nothing too exciting until I got a text from Manolo saying he had found a Yellow-browed warbler in Montjuïc mountain, right in the middle of Barcelona. The bird seemed to be ringed in one of the record shots Lucy managed to take, so we decided to come back late in the afternoon to try to take better photos. Things went actually interesting when Manolo pointed out that he had not heard it a single time giving the typical Yellow-browed call but some Hume’s-like sounds instead. The bird was not cooperative and they had only got poor views and breif vocalisations, but he already got the feeling of a grey bird.

After having seen some Yellow-broweds this spring in the Canary Islands (like the one below), I was aware of how grey they can get when worn, so we both knew we had to focus on sound recordings in order to clarify the identification of the bird.

yellow browed

There were quite a lot of birds in the area, including some nice migrants for  the patch, such as Turtle dove and Golden oriole, but after a couple of hours without relocating the bird, we were sitting in the grass, just chilling, waiting for the other to say we should leave. Suddenly, the bird called behind us, almost in the same tree Manolo had found it in the morning. This time, the call sounded just like a Hume’s leaf warbler! After some search that produced some new birds (at least 2 Western Bonelli’s warblers, either they were not there or it’s incredible how many birds do we miss despite intensive search), we located the bird and managed to take decent photos.

inor_humei1

inor_humei2

Apart from what looks like an extensively black bill, the rest of the bird looked like what I’d expect from a Yellow-browed by this time of the year: pure white wing bar in the GCs, green tones in scapulars and mantle, well-defined facial marks and a still visible 2nd wing bar in the MCs. However, we both agreed we had heard a Hume’s.

To get a sound recording suddenly turned out to be critical, so we just followed the bird with my cell phone pointing towards it, until it eventually happened. Again, as in the previous 3 times we had heard it, the call was not that of a Yellow-browed and reminded more of a Hume’s. This time, however, we had a recording for a later analyse.

sonogram inor_humei2

As can be seen in the comparison with Hume’s and Yellow-browed (taken from Xeno-canto), it definetely looks (sounds) like Hume’s. After having checked almost all the recordings in this website, I’ve not been able to find a single Yellow-browed with a decrecent end. In the other hand, and despite the high variability described for this species, all the Hume’s end with this downward inflection. To summarize the variation, the standard Yellow-browed call looks, in sonograms, like a V; the standard Hume’s looks like an upside-down W, with the angle of the first V more acute.

So, as Manolo said, “why it’s never easy?” It’s true, we never find a Pelican, we usually have to deal with shy uniform warblers and when they are a nice and barred species, there’s a conflict between call and appearence. Since our experience with Hume’s leaf warbler is low (none in my case!), comments on the bird are more than welcome. In the meanwhile, we’ll wait for the pelican.

PS: Many many thanks to Manolo for cheering up the spring 🙂

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