Subject: Pale-legged Leaf Warbler-is it possible to identify? [Print This Page] Author: brendank Time: 5/12/2010 21:52 Subject: Pale-legged Leaf Warbler-is it possible to identify?
Had this warbler today on Lamma Island near Lo So Shing. The primary projection on this bird looks quite short and it is winter.
Is it safe to say it must be Pale-legged Leaf Warbler (rather than Sakhalin)?
The photos are not very good, and only show a limited view. For example, it would be good to have a veiw of the lower mandible from below.
In my opinion, features that fit Pale-legged are:
1. Pale leg, 2. short primary projection.
Features that do not fit Pale-legged are:
1. The wing bars are too thick.
2. Time of occurrance. What is the previous latest record for Pale-legged?
Things that are uncertain to me.
1. Whether the tertials have a clear pale edge.
2. The color of the lower mandible from below.
There is good chance that this is Pale-legged, but I don't think I can make a definite conclusion here.
HF Cheung Author: tmichael Time: 6/12/2010 19:14
re 2. Time of occurrence. What is the previous latest record for Pale-legged? (question in HF's previous post).
In some winters there have been quite a few, specifically in less "core" woodland in areas such as Sai Kung (seen by me in varying nos. in at least two winters ie Dec to Feb, plus heard quite a few times in those winters suggesting bigger nos.) and Lamma (seen by Paul Leader in the past I think).
These birds have looked like tenellipes ("Pale-legged") to me in the past, but of course it is really tough/impossible to be certain.
Mike Turnbull Author: brendank Time: 7/12/2010 13:41
Here is another photo.
The last record of Sakhalin's Warbler appears to be in November so it would seem to favor Pale-legged Leaf Warbler. It seems to be impossible to tell for certain though.
The bill fit Pale-legged. The record is good, I think.
HF Cheung Author: ajohn Time: 7/12/2010 17:26
As far as I know, there are still no established criteria for separating Pale-legged (Ph. tenellipes) and Sakhalin Leaf Warblers (Ph. borealoides) in the field (at least, unless they are singing!). Plumage seems to be almost identical, and calls seem to be inseparable. I think that Mark Brazil lists some features in Birds of East Asia, but I;m not sure how reliable these are, especially outside the breeding season. Primary projection may be useful (Sakhalin is slightly longer-winged, and should have more primaries visible), but there is overlap between the two species.
Based on birds trapped and measured, Sakhalin appears to be a slightly later migrant that Pale-legged. As Mike mentions, individuals of the species pair winter in most years - the only birds trapped in winter have turned out to be Pale-legged, but there have been very few of these (four individuals) so it's possible that Sakhalin also overwinters.
Based on the apparently shortish primary projection (although not very clear on these photos) and the time of year, it seems that there is a good chance that this is Pale-legged, but I'm not sure I would want to say that for certain! Author: brendank Time: 9/12/2010 11:51
Thanks for the information! Seems since there are very few spring records when birds could possibly be singing there is little chance of being able to get two ticks from this species group.
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