Tuesday, September 1, 2009

Marshall Iliff sighting (of heron, that is)

Subject: Great White Heron in Fairhaven continues (26 Aug)
From: Miliff(AT)aol.com
Date: 27 Aug 2009 11:09am


I dropped down to Fairhaven yesterday (26 Aug) morning to look for the Great White Heron that Carolyn Longworth found last month. The first spot I checked was Edgewater Rd., which was where the most recent report came from. As soon as I arrived I spotted the bird feeding along the shoreline with houses well out to the right. The bird was in view for about 5 minutes (7:00-7:05) before flying back into a cove where it was hidden from view. I waited for another 30 minutes and when it did not reappear I tried to find a vantage from which I could see the bird, but failed. I returned at 8:30 and found the bird sitting in a tree, again well out to the right (south). Too distant for photos, but it provided good scope views.

I still find it fascinating that a relatively rare subspecies with an extremely restricted range in Florida, Cuba, and the Yucatan should occur in the Northeastern US with the frequency that it does. Virginia has ~4 inland records and 2 coastal, Maryland has 4, New Jersey has ~4, New York has 2-4, Rhode Island has one, Massachusetts now has 2, and Maine got its first this week. Records seem to be on a rapid rise. It remains uncertain to me if some (or all?) of these records could pertain to leucistic Great Blues and if field observations could ever conclusively eliminate that possibility. Thus far though, records are consistent with natural dispersal from south Florida or more distant breeding areas. Regardless, this is a neat bird, its taxonomic affinities (is it a species or a subspecies) may be someday revisited, and I certainly recommend that Massachusetts birders go see it and try to keep track of how long it stays. Congratulations for Carolyn's keen eye
in picking this bird out, which could have been passed off as a Great Egret to the unwary observer.

Other birds of interest in the area included: multiple Saltmarsh Sharp-tailed Sparrows (Edgewater Rd.), Prairie Warbler and Warbling Vireo, both presumed migrants (Edgewater Rd.), Am. Oystercatcher and Willet (1; ssp. uncertain).


Marshall Iliff
miliff AT aol.com
West Roxbury, MA

Marshall Iliff email -July 10

Regarding Carolyn Longworth’s white heron: http://clongworth.smugmug.com/gallery/8757052_tQSi5#586617827_rkVbD

Although I am in Maryland now and not watching Massbird closely, Jeremiah Trimble just pointed these photos out to me and I was shocked to see that they showed a GREAT WHITE HERON (or white Great Blue—see below)! Salient points are:

-Large size, with very large head and bill

-Pale legs

-Gape line does not extend past the eye

White Great Blue Herons on the East Coast have traditionally been presumed to pertain to the white form from Florida, Cuba, and the Yucatan, known as Great White Heron (Ardea herodias occidentalis). There are now 15+ records north of Florida, including at least 5 from VA, 4 from MD, 2 from DE, ~3 from NJ, several from NY, one from RI, one from MA (Nauset Marsh, recently accepted by the Massachusetts Avian Records Committee), and a few from Atlantic Canada. See the map in Sibley’s article (links below).

It remains unclear (to me) whether leucism or albinism on Great Blue Heron could produce some of these birds, and it remains surprising that true Great White Heron, which has a small breeding population and occurs no closer than southern Florida, would stray northward with such frequency when species with similar or more northerly ranges (Reddish Egret, Roseate Spoonbill, and Wood Stork) occur only slightly more frequently, or even more rarely (for the spoonbill). The pattern of records in some locations (e.g., 3-4 records at inland Lake Pymatuning in PA) suggest perhaps that certain breeding populations of Great Blue Heron may have recurring white individuals, which would obviously be difficult (at best) to distinguish from Great White Heron. Furthermore, nests have been found in Texas with a mix of white and blue fledglings: does this alone mean that Great White Heron should not be IDed in the field? David Sibley has provided some notes on how to distinguish Great White Heron http://sibleyguides.blogspot.com/2007/11/great-white-heron-not-just-color-morph.html. A worthwhile read which goes into more detail than I am providing here and interesting to note his comments at the beginning, in particular.

The bill color in the photos looks dark, which surely contributes to the confusion. This is either some photo illusion or mud on the bill, since this is clearly a Great Blue Heron by size, structure, and leg color. Old World Great Egrets (Ardea alba alba, Ardea alba modesta, or Ardea alba melanorhyncha) have black bills but also have black legs, more dainty structure, and a gape line extending well past the eye. North America’s first Old World Great Egret (away from Alaska, with a few records of A. a. modesta) summered in Virginia last year and showed leg color typical of the African-breeding (and thus most expected) A. a. melanorhyncha.

From David Sibley (various emails)

This is definitely a Great Blue Heron of some form, and whether it's "just" an abnormal white version of the local Great Blues or a Great White Heron from Florida will be difficult to ascertain. It doesn't have any plumes (so presumably it's not an adult) and it also has pretty messy feathers on the wing coverts and back, looking like molt (so it's not a fresh juvenile) and I suspect it's about a year old. If it looks larger than the local Great Blues that would be a pretty strong indication that it's from Florida. There's not much else to go on.

Either way it's a very unusual and interesting bird.