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.