Subject: [Tweeters] [BIRDWG01] Nisqually egret: wrong species?? (fwd)
Date: Jan 25 15:57:35 2011
From: Ian Paulsen - birdbooker at zipcon.net


HI:
Another view of the mystery egret at Nisqually!

sincerely
--

Ian Paulsen
Bainbridge Island, WA, USA
Visit my BIRDBOOKER REPORT blog here:
http://birdbookerreport.blogspot.com/

---------- Forwarded message ----------
Date: Tue, 25 Jan 2011 17:53:15 -0500
From: "Pratt, Doug" <doug.pratt at NCDENR.GOV>
To: BIRDWG01 at LISTSERV.ARIZONA.EDU
Subject: [BIRDWG01] Nisqually egret: wrong species??

Hi birders:

Pierre-Andre commented that this bird did not look as long-necked as the European alba he is used to seeing, and seemed to have a shorter bill. Then the light went on in my head. I had been bothered by the same thing because our North American GWEs are also long-necked and long-billed. The reason we are having trouble figuring out which subspecies of Great White Egret this bird represents is that it may NOT be a Great White Egret! In fact, this bird has every field mark of the Australian subspecies of Intermediate (or Yellow-billed) Egret Ardea intermedia plumifera (Kushlan & Hancock taxonomy). Note that this is not the form one would expect to turn up in North America (A. i. intermedia of East Asia), with which I am familiar as a wintering bird in Micronesia. That is why I failed to pick up on the clues at first, and took the consensus ID at face value. On thing I can say from my experience is that GWE and Intermediate egrets are not as easy to tell apart as you might!
think. Here are the reasons why this bird could be an Intermediate Egret:

Structure:
1. This bird lacks the long neck with a sharp kink that we see in GW Egret. Rather, it has a relatively smooth S-curve to the neck, as in Intermediate. Yes, there is a bit of a kink, but that's OK based on what I have seen in Micronesia.
2. The gape line extends to the back of the eye, but not beyond. This is a tricky feature, because this is the zone where there is overlap between Intermediate and GWE. But GWE usually has the gape line much further back than on the Nisqually bird. It shows particularly well in the photo with the bill open.
3. The top of the head is peaked, not flattened as in GWE. One field guide called the shape a "rounded triangle" while another refers to the steeper forehead of intermedia.
4. The bill is relatively short and thick, about the length of the rest of the head, whereas GWE usually has a bill longer than the rest of the head. In subjective terms, the bill and head shape combine to give this bird a more gentle look than the fierce expression of GWE.

Colors:
1. I have been troubled all along by the intense orange color of this bird's bill. In fact, it would be extreme even for a high breeding A. a. egretta. But it is just what one would expect for A. i. plumifera as hormones begin to kick in. The bill in this form is bright orange-red at high breeding.
2. Loral color is fine for either GWE or Intermediate, but not this time of year. This bird's hormones may be out of whack.
3. Leg color is also exactly what one would expect for A. i. plumifera (I see a slight reddish tinge in some shots; Also, I think we have some mud problems that account for the greater and lesser amount of paleness among the various photos.) I have never seen, out of hundreds, maybe thousands, of birds, an example of A. a. egretta with such leg color. Those legs are always black, top to bottom, year round. Legs of A. i. plumifera are variably dark distally and pale proximally, and approach bright red at high breeding. In the field guides, they look just like those of the Nisqually egret.

I would like to hear from some Australasian birders on this call. What I have outlined took a lot of literature digging, and I found frequent conflation of features among the 3 subspp. of intermedia that was quite confusing.

Of course, if this bird turns out to be what I suggest, we will have to speculate as to how it got to the west coast of North America. Could be a ship-assisted vagrant.

Doug Pratt


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H. Douglas Pratt, Ph. D.
Research Curator of Birds
North Carolina State Museum of Natural Sciences
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