查看完整版本: Some thoughts on taxonomy of gulls in HK

Some thoughts on taxonomy of gulls in HK

In an attempt to sort out some of the gull species that occur in Hong Kong (HK) I've looked at the taxonomy of the ones in the text below. I feel it might be a good starting point for gull-watching in HK and thought it might be useful to other birders and to share it with you here. Secondly, it can be viewed as an addition to this post: [url]http://www.hkbws.org.hk/BBS/viewthread.php?tid=4068&highlight=taxonomy.[/url]

Needless to say, the taxonomy of (large) gulls is complex and evolves frequently. A subspecies several years ago might be a full species today and perhaps a hybrid tomorrow.

I hope it might shed some more light on gulls, to some (a few?) of you that share an interest in this 'difficult' group of birds. I would welcome comments, of course. Maybe I have been wrong in some statements and would be grateful if these would be corrected.

I'll write on four species and discuss their taxonomy and, if relevant, briefly their occurrence in HK. My starting point is the OIC Bird List, which can be found online (see references below). I regard this list as being up to date.

Then I discuss the names that are given in different literature, i.e. books that most people would use when bird watching in HK and especially looking for gulls.

At the end of each species I give some personal thoughts. However, these are not based on personal scientific research and perhaps could be taken with a grain of salt. This thread is wide open for discussion, debate, change and improvement. Besides, "what's in a name"… ;-).

Bart

[[i] Last edited by badesc at 25/01/2013 02:22 [/i]]

Mew Gull (Larus canus) - according to the HK List (2)

Following the OIC Bird List, there are four subspecies:

L. c. canus
L. c. heinei
L. c. kamtschatschensis
L. c. brachyrhynchus

The nominate race, L. c. canus, and L. c. heinei, are called Common Gull by Brazil 2009 and by Olsen and Larsson 2003. Viney et al. 2005 call it Mew Gull (Larus canus kamtschatschensis). The HKBWS 2012 calls it Mew Gull (Larus canus)
Olsen and Larsson 2003 split it up as follows:

Species:

Common Gull (Larus canus)

Subspecies:
L. c. canus
L. c. heinei
L. c. kamtschatschensis

Subspecies L. c. heini has no English name.

Subspecies L. c. kamtschatschensis is called Kamchatka Gull, which is also the case in Birds of East Asia.

Olsen and Larsson 2003 state Mew Gull (Larus brachyrhynchus) to be a separate species and the Nearctic counterpart of Common Gull (Larus canus). So in HK (and the rest of the Palearctic), all Mew Gulls would be Common Gulls according to Brazil 2009 and to Olsen and Larsson 2003. And more specific, most in HK would be Kamchatka Gulls.

Confusion:

Kamchatka Gulls in HK are not viewed as a full species, but as a subspecies of Mew Gull and are called as such. But Mew Gull is sometimes viewed as a species (Larus brachyrhynchus), so the Kamchatka Gulls would then be a subspecies of Common Gulls, which according to OIC Bird List is called Mew Gull.

My personal thoughts:

Common Gull for L. c. canus
Common Gull 'subspecies heinei' for L. c. heinei
Kamchatka Gull for subspecies L. c. kamtschatschensis
Mew Gull for (sub)species L. (c.) brachyrhynchus

In HK, most would then be Kamchatka Gull (L. c. kamtschatschensis). 9 probable Common Gulls 'subspecies heinei' (L. c. heinei). 1 Mew Gull (L. (c.) brachyrhynchus). Status according to the HK List (2)

[[i] Last edited by badesc at 24/01/2013 22:44 [/i]]

Heuglin's Gull (Larus fuscus) - according to the HK List (2)

Following the OIC Bird List, this gull is called Lesser Black-backed Gull and there are five subspecies:

L. f. graellsii
L. f. intermedius
L. f. fuscus
L. f. heuglini
L. f. barabenis

They specifically treat L. f. heuglini, known as Heuglin's Gull, as a subspecies.

The decision to view Heuglin's Gull as a subspecies of Lesser Black-backed Gull is based on Collinson et al. 2008.

Brazil 2009 calls L. f. heuglini Heuglin's Gull and treats it as a species (Larus heuglini). He also mentions a subspecies of Heuglin's Gull, L. h. taimyrensis, but concludes that is "often considered an intergrade between Vega [Gull] and Heuglin's [Gull]".

Olsen and Larsson 2003 treat Heuglin's Gull as a full species too and mention ' taimyrensis' as a presumed hybrid. They call Larus heuglini as an unclear taxonomic status.

Viney et al. 2005 and HKBWS 2012 treat Heuglin's Gull (Larus heuglini) as a species.

Confusion:

Like the situation is today in HK, there is not really any confusion. Although Heuglin's Gull could be called Lesser Black-backed Gull, perhaps very few people would know what one would mean by that.
My personal thoughts:

Heuglin's Gull is correct, but following the OIC Bird List and thus Collinson et al. 2008, the scientific name is Larus fuscus, as in the HK List (1) and (2), or the full scientific name is Larus fuscus heuglini.

[[i] Last edited by badesc at 24/01/2013 22:42 [/i]]

Caspian Gull (Larus cachinnans) - according to the HK List (2)

Following the OIC Bird List, there are no subspecies. But there is al lot of confusion.

Brazil 2009 calls Caspian Gull Mongolian Gull (Larus mongolicus). According to the OIC Bird List mongolicus is a subspecies of Vega Gull (Larus vegae).

Collinson et al. 2008 treat Caspian Gull (Larus cachinnans) as monotopic, but consider mongolicus not as a subspecies of Vega Gull (Larus vegae), but as a subspecies of American Herring Gull (Larus smithsonianus). Vega Gull itself is, according to Collinson et al. 2008, also a subspecies of American Herring Gull.

Olsen and Larsson 2003 use the name Caspian Gull (Larus cachinnans), but recognize three subspecies:

L. c. cachinnans
L. c. barabensis
L. c. mongolicus

Plus a presumed subspecies:

L. c. ponticus

L. c. barabensis is called Steppe Gull. They view barabensis as a subspecies of Caspian Gull or as a subspecies of Heuglin's Gull (which, by others, is seen as a subspecies of Lesser Black-backed Gull).

L. c. mongolicus is called Mongolian Gull. They describe mongolicus as closely related to, and therefore maybe a subspecies of, Vega Gull (which, by others, is seen as a subspecies of American Herring Gull).

In Viney et al. 2005 Caspian Gull is named Yellow-legged Gull, with the scientific name Larus cachinnans (mongolicus). Same for HKBWS 2012 (Larus cachinnans mongolicus). This is confusing, because the OIC Bird List, Collinson et al. 2008 and Olsen and Larsson 2003 regard Yellow-legged Gull as another species: Larus michahellis, which does not occur in the Eastern Palearctic, and thus not in HK. This is because, many years ago, Yellow-legged Gull was the name for Larus cachinnans, and L. c. michahellis was considered a subspecies (Grant 1986). This species (or subspecies, because in the past all large 'silver-backed/white-headed gulls' from the Northern Hemisphere were considered to be Herring Gulls (Larus argentatus)) was later split in Yellow-legged Gull (L. michahellis) and Caspian Gull (L. cachinnans).

Confusion:

There is a lot of confusion within this complex, but only Caspian Gull ssp. L. c. mongolicus ('Mongolian Gull') occurs in HK.

My personal thoughts:

I feel Mongolian Gull for Larus cachinnnas (mongolicus) is definitely better than Yellow-legged Gull, because this name has been given to another species. Mongolicus and michahellis are genetically distinct from each other (Collinson et al. 2008).

Mongolian Gull can be Larus cachinnans mongolicus (following Olsen and Larsson 2003) and Larus smithsonianus mongolicus (following Collinson et al. 2008). So the name Mongolian Gull makes sense. The scientific name is open for more debate, though.

What confuses me most in the names, is that Mongolian Gull is either a subspecies of Caspian Gull, but does not occur in the Caspian Sea area, or either a subspecies of American Herring Gull, but does not occur in America. Mongolian Gull is allopatric. But Collinson et al. 2008 mention the close relationship to smithsonianus, from which mongolicus might descend from.

[[i] Last edited by badesc at 24/01/2013 22:41 [/i]]

Vega Gull (Larus vegae) - according to the HK List (2)

Following the OIC Bird List, there are two subspecies:

L. v. vegae
L. v. mongolicus

Brazil 2009, Viney et al. 2005 and HKBWS 2012 all treat it as a full species. Olsen and Larsson 2003 too, but ad that its taxonomic status is unclear.

Confusion:

Because the OIC Bird List sees Mongolian Gull as a subspecies of Vega Gull (L. v. mongolicus) it makes it more complex. As we have seen above, Mongolian Gull has been called:

a species, Mongolian Gull (Larus mongolicus), by Brazil 2009
a subspecies, Larus smithsonianus mongolicus, of American Herring Gull, by Collinson et al. 2008
a subspecies, Larus cachinnans mongolicus, of Caspian Gull, bij Olsen and Larsson 2003
a (sub)species, Yellow-legged Gull (Larus cachinnans (mongolicus)), by Viney et al. 2005
a (sub)species, Yellow-legged Gull (Larus cachinnans mongolicus), by HKBWS 2012

And Vega Gull itself is considered a subspecies of American Herring Gull (Larus smithsonianus vegae) by Collinson et al. 2008, together with Mongolian Gull (Larus smithsonianus mongolicus).

My personal thoughts:

Following Collinson et al. 2008, it would mean that Caspian Gull, which is actually Mongolian Gull in HK, and Vega Gull are both American Herring Gulls.  Following the OIC Bird List, Caspian Gull (Larus cachinnans) and Vega Gull (Larus vegae), as such mentioned on the HK Bird List (2), should be the species Vega Gull on the list.

[[i] Last edited by badesc at 25/01/2013 02:25 [/i]]

References:

[url]http://www.worldbirdnames.org/n-shorebirds.html[/url]
[url]http://www.hkbws.org.hk/BBS/view[/url] ... highlight=HK%2Blist (1)
[url]http://www.hkbws.org.hk/BBS/view[/url] ... highlight=HK%2Blist (2)

Brazil, Mark, 2009. Birds of East Asia
Collinson, J.M., Parkin, D.T., Knox, A.G., Sangster, G., and L. Svensson, 2008. Species boundaries in the Herring and Lesser Black-backed Gull complex. British Birds 101(7):340-363 ([url]http://www.britishbirds.co.uk/search?id=9395[/url]).
Grant, P. J., 1986. Gulls: A Guide to Identification
Olsen, Klaus Malling and Larsson, Hans, 2003. Gulls of Europe, Asia and North America
[HKBWS] The Hong Kong Bird Watching Society, 2012. A Photographic Guide to the Birds of Hong Kong
Viney, Clive, Phillipps, Karen and Lam, Chiu Ying, 2005. The Birds of Hong Kong and South ChinaOlsen, Klaus Malling and Larsson, Hans, 2003. Gulls of Europe, Asia and North America
[HKBWS] The Hong Kong Bird Watching Society, 2012. A Photographic Guide to the Birds of Hong Kong
Viney, Clive, Phillipps, Karen and Lam, Chiu Ying, 2005. The Birds of Hong Kong and South China