Eurasian/American splits (2 Viewers)

[Richard Klim]

Callahan 2010. Taxonomy: Split infinity. Birdwatch 214: 32-35.

David Callahan outlines potential future splits of Holarctic species into Palearctic and Nearctic forms, focusing on likely transatlantic vagrants.
[A reference list will reportedly be available at www.birdwatch.co.uk, but it doesn't seem to have been posted yet.]

Richard

 

[Mysticete]

is there a link to the actual article, and if not would it be possible to get a PDF?

Thanks

Morgan

 

[Richard Klim]

is there a link to the actual article, and if not would it be possible to get a PDF?

Sorry Morgan, Birdwatch isn't published online (although a reference list will reportedly be posted on the website).

The following possible split candidates are suggested in the article [authorities already recognising indicated], although it's acknowledged that some of these are unlikely. I suspect that most/all are anyway familiar to regulars on this forum.

• Anser (albifrons) flavirostris
• Branta (bernicla) hrota [DB]
• Branta (bernicla) nigricans [DB]
• Branta (bernicla) ssp ('Gray-bellied Brant')
• Fulmarus (glacialis) rodgersii
• Nycticorax (nycticorax) hoactli
• Ardea (alba) egretta
• Pandion (haliaetus) carolinensis
• Circus (cyaneus) hudsonius
• Buteo (lagopus) sanctijohannis
• Falco (columbarius) richardsonii
• Falco (columbarius) aesalon
• Gallinula (chloropus) galeata
• Charadrius (alexandrinus) nivosus [IOC]
• Calidris (alpina) hudsonia
• Numenius (phaeopus) hudsonicus [DB]
• Rissa (tridactyla) pollicaris
• Larus (canus) brachyrhynchus
• Sternula (albifrons) antillarum [IOC, BLI, Clements, H&M3, HBW, AOU, DB]
• Chlidonias (niger) surinamensis
• Sterna (sandvicensis) acuflavida [IOC]
• Lanius (excubitor) borealis [DB]
• Eremophila (alpestris) flava
• Hirundo (rustica) erythrogaster

Richard

 

[Hotspur]

The split of aesalon from columbarius i assume contains subaesalon? Will it then be Eurasian Merlin, American Merlin & Taiga Merlin. Im not that familiar with the Merlin situation.

 

[Richard Klim]

Merlin

The split of aesalon from columbarius i assume contains subaesalon? Will it then be Eurasian Merlin, American Merlin & Taiga Merlin. Im not that familiar with the Merlin situation.

The article suggests that "the Taiga [nominate columbarius] and Prairie [richardsonii] subspecies of American Merlin have to be considered as potential species", which would implicitly leave F (c) aesalon encompassing all Eurasian taxa (including subaesalon).

It's not stated whether F (c) columbarius would include suckleyi 'Black Merlin' (an unlikely vagrant to Europe). [Cornell/Clements treats suckleyi as a separate monotypic 'group'.]

Richard

 

[Richard Klim]

References

Reference list now posted:
http://www.birdwatch.co.uk/categories/articleitem.asp?item=559

Richard

 

[dantheman]

Shoveler? Any chance of that being split (or are there even any visible differences?)

Reason I ask is that about 10 years ago on Teneriffe on one of the concrete 'reservoirs' were 3 ducks feeding together on the green algae - an American Wigeon, a Green-winged Teal ... and a Shoveler...

Hhhmmm ...

 

[Richard Klim]

Northern Shoveler

Shoveler? Any chance of that being split (or are there even any visible differences?)

Anas clypeata is universally considered to be monotypic.

About the best I can offer to stretch the case for a split is this from Dubowy 1996 (BNA Online):

"Geographic Variation
Some variation in coloration of ducklings noted. Nearctic and some palearctic ducklings have tarsi and toes colored a contrasting shade of orange and grayish brown, whereas other palearctic ducklings have tarsi and toes of a dark greenish or olive tint (Nelson 1993). No variation known for adult birds."​

Richard

 

[dantheman]

Drat, we should have gathered a sample for breeding ... (ok, maybe not, and it wouldn't have helped much I guess anyway...)

Cheers

 

[SteveO43]

Reference list now posted:
http://www.birdwatch.co.uk/categories/articleitem.asp?item=559

The link appears to be to the references rather than the article itself.

Is there a link to the article?

 

[Richard Klim]

Is there a link to the article?

No, the article isn't available online. But it's anyway just a brief round-up of possibilities (probably intended for birders who don't usually follow taxonomic developments) – it doesn't present new evidence.

Richard

 

[Farnboro John]

Well, I reckon I'm sure I've seen seven of those over here, and I've a reasonable guess that the 1985 Scilly Night Heron was hoactli - it fell out of the sky while it was raining Yanks anyway - Rough-legs in similar conditions hmmmmm.......

God help us if we have to scrutinise every Moorhen on Scilly every October!

Hours of fun for all the family.

John

 

[Richard Klim]

Common Gallinule

God help us if we have to scrutinise every Moorhen on Scilly every October!

Easy – the cachinnans would be the one having a laugh. :-O
Richard

PS. Gallinula galeata today recognised by AOU-SACC (proposal #416).
http://www.museum.lsu.edu/~Remsen/SACCproproster.html

 

[birdboybowley]

Slightly off-topic geographically, but the joking around about Shovelers made me wonder what's the current thinking on Oz and NZ Shovelers?? Are they still the same bird, diff subspp? They look alot more different to each other than some other splits I can think of...

 

[Richard Klim]

Australasian Shoveler

...what's the current thinking on Oz and NZ Shovelers?? Are they still the same bird, diff subspp? They look alot more different to each other than some other splits I can think of...

Having never been down under, I've got absolutely zero experience of Anas rhynchotis, and don't know anything about the latest thinking in Oz or NZ. Two sspp are usually recognised (variegata in NZ), and the species isn't split by any of the major world checklists (IOC, BLI, H&M3, Cornell/Clements). But Ogilvie & Young 1998 (Wildfowl) commented: "Although two geographically separated subspecies have long been recognized, ...the plumage distinctions are so small in relation to known individual variation as to throw doubt on validity of subspecific division..."

Richard

 

[Mysticete]

actually looking at this list, I am surprised they have left off American Great Egret. On the East Coast last year I believe there was a representative of the old world form found and identified, and they seem as valid a split as the Night Herons listed

What about Common Merganser/Goosander? I have heard that suggested as a possible split?

 

[Richard Klim]

American Great Egret

actually looking at this list, I am surprised they have left off American Great Egret.

It's on the list of candidates: Ardea (alba) egretta, [or Egretta, or Casmerodius if you prefer...] – although David Callahan suggests that a split is unlikely in this case.

You're working too hard, Morgan.

Richard

 

[Richard Klim]

Common Merganser

What about Common Merganser/Goosander? I have heard that suggested as a possible split?

Yes, eg Steve Howell identifies it as a candidate in this posting on ABA's The Eyrie which you raised on this forum last October:
http://birding.typepad.com/youngbirders/2009/04/steve-howell-3.html

But perhaps an unlikely transatlantic vagrant?

Richard

 

[chris butterworth]

Splitting Chlidonias niger? I know surinamensis looks very different to the nominate but genetically it is very close to the birds from the Eastern Palearctic, and they are niger. Doesn't work for me. The whole list looks cobbled together with some proposed "splits" that probably are valid, and others that seem to be based on "Nearctic birds are sometimes different from Palearctic ones, so we're splitting them all" vis A. albifrons, F. glacialis, B. lagopus, C. alpina, R. tridactyla, E. alpestris and H. rustica.Chris

 

[Richard Klim]

American Black Tern etc

Splitting Chlidonias niger? I know surinamensis looks very different to the nominate but genetically it is very close to the birds from the Eastern Palearctic, and they are niger. Doesn't work for me. The whole list looks cobbled together with some proposed "splits" that probably are valid, and others that seem to be based on "Nearctic birds are sometimes different from Palearctic ones, so we're splitting them all" vis A. albifrons, F. glacialis, B. lagopus, C. alpina, R. tridactyla, E. alpestris and H. rustica.

Well, to be fair to the author (and as I hope I conveyed in post #3, and I should clarify that the speculative bi/trinomials are mine), the article identifies possible candidates for consideration, but acknowledges that some are rather unlikely to be split.

Re Chlidonias niger surinamensis, David Callahan comments: "Genetically, the subspecies is not as different as its plumage might suggest, being apparently relatively recently derived from the Asian populations of the Eurasian subspecies, but the form is geographically isolated and its plumage is diagnosable at all ages".
FWIW, Birding World and UK400 Club split C niger (although of course neither qualifies as a peer-reviewed taxonomic decision ).
http://www.birdforum.net/showthread.php?p=1649880
http://www.uk400clubonline.co.uk/File-Store/UK400ClubWPMasterList-Nov08-XXXX.XLS

Richard