Tuesday, December 2, 2008

Photo Quiz

This was taken on Sept 17. 
Good luck! 

If you prefer gulls here's one:  http://www.pbase.com/image/106641022
One of these gulls is a Thayer's. Which one?  


Naturepixels said...

Your poll on Thayer's makes no sense. Which species concept are you basing this on? The Biological Species Concept would group them differently from the Phylogenetic Species Concept.

If you take Mitochondrial DNA analysis into account you would have them group differently as well.

David Bell said...

I'll say bwte for the duck. I thought you said THGU's couldn't be ID'd? The far one is the THGU though, has a nice primary pattern.

JoshC said...

BWTE for the duck, and the back bird for the THGU one.

Yeah, I thought you said the THGU is impossible to ID with out every single field mark possible.

Chris W said...

I'm not sure why I have to clarify everything but allow me to do so here. THGU can't be IDed with any certainty. Here, the back bird is "most likely" a Thayer's Gull. Therefore, that's what it's been called.

Now think about the other birds (or animals) that hybridize. Can you really call them one species or another? I don't think so because you can't know how pure the bird is. For the purposes of abbreviation, we can call it the species that it is most likely to be. End of story.
Some of you know how hard we tried to find a pure LABU. No go. But those were the obvious hybrids. Good luck with ones that aren't so obvious.

The Texas BRC does this with Purple/Rock Sandpipers. They call it Purple until proved otherwise because PUSA/ROSA cannot be readily or easily differentiated in the field.

and BTW, the species concept that I know best and use is the biological one.

Anonymous said...

I know for a fact I have never seen a HERG with a) that much streaking on it's head (far bird, forget the primary pattern!) and b) legs that dark on the near bird. Shape of either is also very delicate for any HERG, more akin to Iceland.

Anonymous said...

Ok this is going to a tipping point... I haven't heard of anyone considering ROSA and PUSA too close to call in plumage (try Cordilleran and Pacific-slope Flys and I might agree!), and what does a Lark Bunting hybridize with?!

Chris W said...

My bad on the code. I meant LAZB.
COFL and PSFL are indeed too close to call without the audio.
Check out the recent discussion on Tex-birds for the ROSA vs PUSA thing.

BTW, I've seen some HERGs with some pretty dark head streaking.

Naturepixels said...

You stated:

"But what about the tricky ones. Let's try Thayer's Gull. Thayer's Gulls are identical to Herring Gulls in every way, except for three small differences. Adult Thayer's Gulls have dark eyes, no black on the underside of the primaries, and brighter, richer pink legs."

After reading that comment I realize that you need to read more gull identification papers and spend more time studying them in the field. You fail to mention anything about head shape and the size of the bill which are diagnostic.

Thayer's have a rounded head and a petite bill. Herring's have flat forehead, which give their head a flatter appearance, and larger stout bill.

You failed to notice that Erik was with Karl Bardon who is one of the midwest's Gull experts. Karl has seen thousands of these gulls and knows them very well.