Eurasian/American splits (2 Viewers)

[Mysticete]

hah...yeah missed that in the scan through. Been working all week in mammalogy collections, so am probably somewhat fried

I do tend to think eventually, when all is said and done, there will probably be quite a bit less overlap between NA and Europe lists as far as species goes.

I wonder if Common Merganser might show up in Iceland at least. I wouldn't have expected Common Shelduck to be a vagrant here, but one showed up last fall in Newfoundland...

 

[Microtus]

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

The bird in question is thought to be of the African form, melanorhynchos/melanorhyncha (sp. ?), not the European form. It had a (largely) black bill during May and I think early June, which gradually turned yellow as the summer progressed. It was distinctly smaller than most of the American Great Egrets that were there. It was present at Chincoteague National Wildlife Refuge in coastal Virginia, in both 2008 and 2009.

 

[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.

Article now posted online:
http://www.birdwatch.co.uk/categories/articleitem.asp?cate=24&topic=120&item=600

Richard

 

[Kirk Roth]

This sentence caught me:

"Differences between Nearctic and Palearctic subspecies can be slight, mainly involving clustered averages in biometrics and body size, as in Red-necked Grebe, or more obvious plumage differences, as shown by Sandwich Tern."

The Sandwich/Cabot's Tern split is one that hasn't set well with me, mostly because they seem so similar to me. I'll grant that this is based on limited and amateurish research and that I've not yet sailed across the pond to see a European Sandwich Tern. When Callahan talks "obvious plumage differences," do you think he's referring to the yellow-billed South American populations vs. the European? Or is there some other glaring difference that I'm blind to?

I've been under the impression that the major difference between Sandwich and North American Cabot's has been size difference, and not all that striking. That, and the Cabot's greater affinity for Elegant Tern genetic code (a difficult field mark, indeed). What else?

 

[Richard Klim]

Sandwich Tern

This sentence caught me:
"Differences between Nearctic and Palearctic subspecies can be slight, mainly involving clustered averages in biometrics and body size, as in Red-necked Grebe, or more obvious plumage differences, as shown by Sandwich Tern."
The Sandwich/Cabot's Tern split is one that hasn't set well with me, mostly because they seem so similar to me. I'll grant that this is based on limited and amateurish research and that I've not yet sailed across the pond to see a European Sandwich Tern. When Callahan talks "obvious plumage differences," do you think he's referring to the yellow-billed South American populations vs. the European? Or is there some other glaring difference that I'm blind to?
I've been under the impression that the major difference between Sandwich and North American Cabot's has been size difference, and not all that striking. That, and the Cabot's greater affinity for Elegant Tern genetic code (a difficult field mark, indeed). What else?

Garner et al 2007 concluded "The plumage and structure of acuflavida and sandvicensis are sufficiently different to suggest that at least some acuflavida should be identifiable in the field":

• Garner, Lewington & Crook 2007. Identification of American Sandwich Tern. Dutch Birding 29(5): 273-287.

It's rather too complex to easily summarise here (giving very detailed analysis of all age groups), but separation seems to require quite advanced identification skills...!

Richard

 

[jurek]

Out of curiosity - was American swallow ever claimed from Europe? That one should be obvious thing to watch?

 

[SzimiStyle]

What is the story behind the 'hudsonia' Dunlin split?

 

[Richard Klim]

Hudsonian Dunlin

What is the story behind the 'hudsonia' Dunlin split?

The reference given is:

• Stoddart 2007. An apparent Hudsonian Dunlin on the Isles of Scilly. Birding World 20(11): 464-466.

In this article Andy Stoddart comments:

• "On both the breeding and wintering grounds, [Hudsonian Dunlin] is geographically isolated from its nearest Dunlin neighbours... As well as showing distinct morphological characters at all seasons, hudsonia also shows a clear genetic divergence..., and there is no gene flow between them. Wenink et al. (1996) identified hudsonia as the ancestral Nearctic Dunlin, emerging in the late Pleistocene, around 223,000 years ago, before subsequent glaciations drove further range fragmentation and subspeciation."
  [Wenink et al 1996. Global mitochondrial DNA phylogeography of Holarctic breeding Dunlins. Evolution 50: 318-330.]

Cornell/Clements identifies hudsonia as a 'subspecies group'; Avibase identifies it as an incipient species, candidate for split.

Richard

 

[SzimiStyle]

Thanks for details. I wonder when it will be seriously investigated or accepted? Would be nice to know before we prepare the Dunlin plates for the shorebird book

Szimi

 

[Richard Klim]

Hudsonian Dunlin

I wonder when it will be seriously investigated or accepted?

I'd be surprised if this one is currently under serious consideration by any classification committee. Unless anyone knows otherwise...

Richard

 

[SzimiStyle]

At least we are prepared for the Hudsonian Curlew