kkoel

Q.1




I would like to ask for expert advice on the identity of the two adult gulls left of the adult Heuglin's Gull. My bet for the two big gulls on the left is Vega-type Gulls: I overheard some fellow birders talking about taxon "birulai", so I'll make it the null hypothesis here ^^. Indeed these two birds are smaller, not bigger than the Heuglin's; the legs are pink as portrayed and seen in the field, as compared to the yellow legs of Heuglin's; the neck streaking is comparatively rich; also the mantle colour is paler, but not much paler than the Heuglin's beside them.

Q.2


Second question please: what are the two adult gulls on the right? I would guess Heuglin-? hybrids, because the mantle colour is paler than normal Heuglin's, leg is yellow for one and orange-pink for the other. Also, should the black spot on the bill be interpreted as a mark for 3rd year gulls?

Maipo Boardwalk
23/1/10

Thanks for replies in advance!

[ Last edited by kkoel at 29/01/2010 16:19 ]

kkoel

Thanks Fai Gor for your reply!

kkoel

Hi Geoff,

Thank you for your detailed reply!

For photo 2, I was only referring to the 2 pale-mantled adults on the right (for I'm not confident with the immatures - which I guess are all Heuglin's...) - and I'm sure these two individuals are distinct from the two vegae-type gulls in photo 1 - hope it helps further analysis.

Can I also ask for photo 2, is it possible to interpret the moult pattern of the resting adult gulls with folded wings?

kkoel

Thanks Mike for the detailed comments - next time I'll know better where to look on the gull for ID!

I guess more detailed observation of these big gull taxa in Hong Kong can really help clarify the distribution of the Mongolian / Vega / Heuglin's complex in East Asia, and hence their taxonomic relationships. Given the propensity for juvenile gulls to wander, maybe if we look closely at the young big gulls, we'll find more Vega than we might have noticed! =)

More pics on a possible Vega-Heuglin's hybrid from the same day, the left bird in photo 1 below and the same bird in photo 2.





[ Last edited by kkoel at 29/01/2010 16:22 ]

kkoel

Mike,

Thanks for your reply. It's very interesting to see the range of plumage / structure differences seen in taimyrensis - which actually is understandable if we regard taimyrensis as an intergrade between nominate vegae and heuglini. For the dark-mantled gull on the right of photo 1, I have always been under the impression that it was one of the 'taimyrensis'-type too - as the mantle colour is rather lighter than that of Lesser Black-backed Gull taxon graellesi, whereas for heuglini I've seen some photos from the christopher helm Gull guide portraying a mantle shade darker than graellesi. I guess your revelation will make me reconsider many of my previous 'taimyrensis' as 'heuglini'!

Koel