wgeoff

This bird arrived on Po Toi today, together with an adult leucopsis.



It bears a striking resemblance to the 2006/7 bird that was identified as baicalensis and was also partnered with a leucopsis, photo from 2006 here



Is it baicalensis? Or is it a hybrid, part baicalensis?

[ Last edited by wgeoff at 3/09/2010 08:42 ]

lpaul

Looks like a typical baicalensis to me; what is it that suggests it is a hybrid?  

I note you say that the 2006/7 bird was partnered with a leucopsis - what exactly does that mean?

wgeoff

Black cap does not come down to the bill, black throat not so clean cut, white not so extensive on wings (all compared with 2006/7 bird. Actually I thought at first that it was the 2006/7 bird until I compared the photos)

Now that you've confirmed the Id, I've changed the main title.

Partnered = inseparable from, almost always seen together over a long period of time. I'll send you an email.

[ Last edited by wgeoff at 3/09/2010 08:43 ]

lpaul

Surely these are age/sex related differences?  White Wagtails are notoriously difficult to age and sex unless in adult plumage, even in the hand.

Partnered seems like an odd term to use in this context; I would have thought it meant some sort of breeding association.

I'll send you an email too!

ajohn

Out of interest, how do you identify this as a baicalensis White Wagtail? My understanding was that baicalensis is a pale-backed race (i.e. similar to ocularis), whereas these birds seem to me to be fairly dark-backed (more similar to the colour of a female leucopsis).

Of course, the head pattern does not fit with leucopsis, showing much too black, but surely the darker ear-coverts also do not fit very well for baicalensis? This photo suggests that baicalensis not only has a somewhat different head pattern, but also suggests that it shows more grey on the flanks than the Po Toi birds seem to show:
http://nomadicjourneys.com/press ... e=inline&id=369

I would be interested to hear some feedback. I am not trying to say these birds are definitely not baicalensis - certainly it is a feasible migrant to Hong Kong - but I am slightly puzzled that they do not fit with my expectations for that subspecies. Geoff's suggestion that they seem to be associating with leucopsis also seems intriguing (OK, so that may just be due to them associating with the most similar bird they can find, but it's not something I notice with e.g. ocularis and leucopsis).

lpaul

Some interesting questions coming up, not all of which I know the answer to.  But regarding grey flanks, I think this is a feature of adult males in some eastern taxa (notably baicalensis and lugens).

Baicalensis (in winter plumage) is a grey mantled taxon, with an extensive breast patch, typically meeting the bend of the wing and extending up in an arc onto the rear ear coverts.  There is often a narrow line from the bill base extending onto the ear coverts, and a dark shadow across much of the rear ear coverts.  So, pretty much like the Po Toi birds, really.

As per the adult male in the photo John refers to, an extensive white forecrown is typical of baicalensis.

Jonathmartinez

Wagtail also migrate well in Hunan, and after read this interesting post, i've spent time this afternoon to spot group of wagtail.
I find pretty different kind of individual, no one matching exactly the bird from Po Toi, but some ressembling closely. I've find two bird with breast patch reaching into throat and not well cut as on the Po toi bird, on most of evident "leucopsis" the patch have a clear limit just under the throat. ALso on both birds there is a link from the rear ear-covert to the breast patch. All of them have a medium dark grey mantle with a blackish cap and white forecrown. I found a other bird with a small  breast patch but showing some blackish coming into the throat and also few blackish on ear-covert and thin blackish mallard stripe.
May be i'm totally out of subject, i don't know if there is a link between this birds and the one from Po Toi but seems there is a lot of variation in this migrating group.
At the same place, was 3 "lugens" on 30/08 and a intergrade alboides x leucopsis on 02/09 (thanks again Paul for help on ID), and a 1 cy Citrine Wagtail today...
Below the pics of the 3 birds i speak above.

wgeoff

Hi Johnathon (is that right?)

Your first bird appears to have some black splodges on the back, which I think indicates a first winter male leucopsis. I'm not sure about the second bird.

One feature which has not been mentioned so far is the colour of the rump. I have recently received a copy of the new book 'Advanced Bird Id Guide for the Western Palearctic' by Nils Van Duivenduk. This doesn't include any pictures or photos but has lists of important features for 1300 species and subspecies in the Western Palearctic.

Surprisingly, it does include baicalensis, which it treats as a subspecies of the nominate White Wagtail alba, and leucopsis, which it treats as a separate species Amur Wagtail. It mentions rump colour as a key feature to separate these - black for leucopsis and grey for baicalensis in all plumages (page 257).

Perhaps Paul would like to comment on this as a diagnostic feature.

I hope to get some better photos of this bird next week which show the rump colour.

[ Last edited by wgeoff at 5/09/2010 07:50 ]

Jonathmartinez

Hi Geoff,

Less 1 h, Jonathan
Yes i also was thinking about this black splodges and that should indicate that this bird have more chance to belong to "leucopsis".
But it's interesting to see the variation of the breast patch on this different birds.
I spend time again this morning, on wagtail watching,on near fifty birds spotted i found only one with such black patch coming into the troat but also not so clear cut. I join the photo below, also showing the rump.
The feature of the rump is interesting.
I've find a link showing well the rump of a "baicailensis", looks greyish with some feather with black edge.
http://www.biolib.cz/en/taxon/id686829/

I've check all the pictures of my birds, and they all show well black rump, include this morning bird. So i like the supposition of 1stW "leucopsis", assuming there adulte plumage, that could explain why all of them have so unclear breast patch border, looks like this patch is reducing into a normal adulte "leucopsis" patch.My third bird in my past post, is maybe a first winter with more advanced moulting, more black spodges on back and more reduce breast patch with some few blackish rest in the throat and ear-covert.

Have you the date of the bird of 2006-07.
On your bird the proportion of black on the head and breast patch is more important than on all of my birds, but is also not so well cut, so i don't know what think about. As you said maybe the rump feature is the key to identify this bird. Hope you can get some pics of it.

I will post the pics late over my authorized poor limit file's size per day!

Jonathmartinez

here are the two pics :