This bird was observed yesterday morning, it was not being accepted by the other stilts on the mudflats and reminded me of Black-necked Stilts I had seen in Puerto Rico or is it an adult female Black-winged Stilt with breeding plumage (it seems to have bronze-brown on upper wing section. It could be a White-headed Stilt (Himantopus leucocephalus)
I'm sitting here with my Birds of East Asia and can see why you're asking. I'm not sure if the black in the neck is extensive enough- I've also looked at Birds of Borneo which states that "birds in the boreal winter period have a dusky grey mask descending from the crown over the eyes, and a grey wash over the neck and sides of breast" I've taken a look at the OBC images too and the birds there are more distinctly marked. I'm curious to hear what the boffins back at HQ think. Nice pic whatever the case.
[ Last edited by subbuteo at 12/12/2010 20:42 ] Author: ajohn Time: 12/12/2010 23:15
The taxonomy of stilts is pretty complicated, and there is still no consensus on how many species are involved in the Black-winged Stilt complex (some authorities argue just one species, others as many as five). This is complicated by the fact that each taxon is very variable, especially in terms of head pattern.
Black-necked Stilt Himantopus (himantopus) mexicanus is an American species (see http://www.birdforum.net/opus/Black-necked_Stilt). It has extensive black eextending from the back onto the crown and surrounding the eye (with a small white spot near the eye). This bird clearly does not fit this ID.
White-headed Stilt Himantopus (himantopus) leucocephalus occurs in Australia and Indonesia. It has apparently turned up in Japan as a vagrant, which would suggest it is plausible in Hong Kong. It typically has a white head and neck with a black nape, similar to this bird.
The compication is that Black-winged Stilt has a very variable head pattern (look at the variability in a small numbers of birds here: http://orientalbirdimages.org/se ... _ID=&pagesize=1), and can show a similar pattern to the typical White-headed with a white head/neck and black nape (I have heard this is commoner in south-east Asia than elsewhere, but I don't know if there is definite evidence for this). One key difference seems to be that the black feathers on White-headed are actually longer than the surrounding white feathers, creating a slightly 'fluffy' appearance - compare http://orientalbirdimages.org/se ... Family_ID=&p=8.
The bird in question does not seem to have these longer nape feathers, and therefore seems to me to fit better for Black-winged Stilt. I have seen individuals like this in HK before and similar confusion about the possibility of White-headed Stilt has arisen in the past. Author: tbob Time: 13/12/2010 14:16
Thanks John for the detailed analysis. I was at Nam Sang Wai for around 5 hours that day and all the time the bird in question was harassed by the other Black-winged Stilts that was one of the main reasons I raised the query. Thanks again
Bob Author: subbuteo Time: 13/12/2010 16:07
Typical quality answer- thanks John. I've seen some unusual stilts- especially in Brunei where White-headed were apparently recorded. I never pinned any down though. Good to know it isn't just me that gets puzzled by them.
[ Last edited by subbuteo at 13/12/2010 16:44 ]
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