Wednesday, October 4, 2017

Kamchatka Leaf Warbler in autumn

This morning I took a stroll around the grounds around the Dept of Public Relations, a small area of parkland which serves as the best migrant trap near my house.

Whilst checking a patch of trees where I had seen a male Siberian Blue Robin last week I heard an unfamiliar call - a rather flat, nasal "tik" repeated several times. I was really unsure what might be making the call, but knew that it was probably something unusual as I've pretty much mastered the calls of the common residents and migrants that I encounter in Bangkok.  I soon located the bird making the call and was a bit surprised to find that it was a phyllosc! The bird initially gave very poor views - making me think that perhaps it was one of the species I encounter rarely (such as Claudia's Leaf Warbler), but once I got a proper look at it I determined that it was "just an Arctic Warbler".

But what about that call?! It really didn't sound like the explosive, buzzy "tzik" of an Arctic, but from memory it didn't sound much like either Kamchatka or Japanese. The bird promptly shut up, just as I got my iPhone out to make a sound recording (!) so instead I checked the calls in my playlist - it was clearly not the frog-like call of Japanese LW, but actually sounded much closer to Kamchatka than I remembered, although this bird seemed to be giving just the first part of the call (rather than the full "loose" or "dribbly" call found on the recording I had from xeno-canto).  After some pishing the bird showed again and when I played the xeno-canto recording to it, it quickly moved from the high canopy of a tree some 10 meters away to the lowest branches less than two meters in front of me.  It then started calling with the full version of the call, as if to confirm that I was playing it the right tape!

Whilst identification of Kamchatka vs Arctic based on plumage remains very much in its infancy, one thing that I noticed about this bird was how strikingly white the undertail coverts appeared compared with the flanks (and some of my images suggest a very light suffusion of yellow on the undertail coverts, see below).

There is still lots of work to do on these phylloscs, but some useful resources can be found in the links below:


Craig Brelsford from Shainghai birding  has commented:

The research is out there. All we need to do is apply it. 

Birders fall into habits. They often either get into the habit of attempting IDs on the wrong criteria (plumage and bare parts, for ex., in the case of Pale-Sak and Arctic-Kamchatka), or they get into the habit of throwing up their hands and giving up. 

Neither mistake is necessary anymore in the case of Pale-Sak. The research is out there, and it is saying call is diagnosable. All that is left is for is birders to use that new knowledge.


Philips Huges said...

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Ed said...

Great post!My wife and I are novices but have seen (what i believe to be) a female Siberian Blue Robin and Brown Shrike in the last two days. The park is a great spot. Do you know of any Pink Necked Pigeon sightings here?