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GREAT BLUE HERON
<br />Equally at home in coastal (marine) environments
<br />and in fresh water habitats, the Great Blue Heron
<br />has weathered the impacts of 20th century North
<br />Americans quite successfully, although its
<br />breeding colonies remain vulnerable to dis-
<br />turbance.
<br />DISTINGUISHING CHARACTERISTICS
<br />Largest heron in North America, about 60 cm tall,
<br />97 to 137 cm long, 2.1 to 2.5 kg mass. Middle toe
<br />with small comb (pectinate). Wings long and
<br />rounded, bill long and tapered, tail short. In flight,
<br />folds neck in S -shape and extends legs along the
<br />body axis; deep, slow wingbeats.
<br />Herodias (blue) group: legs and neck long. Long
<br />body and occipital plumes on adults. Upperparts
<br />gray, fore -neck streaked with white, black, and
<br />rust- brown. Bill yellowish. Legs brownish or
<br />greenish. Occidentalis (white) group resembles
<br />herodias except wholly white (some individuals
<br />have a few dark feathers). The Great Blue Heron
<br />resembles the Grey Heron of Europe and Africa,
<br />found occasionally in the West Indies (American
<br />Ornithologists' Union 1983), except that Great
<br />Blues have gray feathers with violaceous tinge on
<br />back and sides of neck, chestnut feathers on thighs.
<br />Adult Grey Heron slightly smaller (90-98 cm long),
<br />with pale &ray neck and white feathers on thighs
<br />(Hancock and Kushlan 1984).
<br />DISTRIBUTION
<br />3U CHECK -LIST REGION
<br />Breeding range. Widespread (Fig. 1). The Great
<br />ue Heron (Herodias group) nests as single pairs
<br />d small colonies along coasts of se. Alaska (61°N;
<br />. Sigman pers. comm.) and n. British Columbia
<br />WB). Mostly in colonies on south coast Butler
<br />1989) and mountain valleys of British Columbia,
<br />in central Canadian Prairies (Vermeer 1969,1970,
<br />1973, Vermeer and Anweiler 1970), s. Ontario
<br />(Gray et al. 1980, Dunn et al. 1985), s. Quebec
<br />(DesGranges et al. 1979), and the Canadian
<br />Maritime provinces (McAloney 1973, Quinney
<br />1982) except Newfoundland (Montevecchi and
<br />Tuck 1987), south to Florida, Texas, Baja California,
<br />and Central America at least to Belize and
<br />Guatemala. Mostly in colonies and along the Pacific
<br />and Caribbean coast of Mexico to Guerrero (AOU
<br />1983). Breeding status unknown in central Mexico.
<br />Occidentalis group (Great White Heron)
<br />restricted to coastal habitats of s. Florida (including
<br />the Keys), Cuba, the Isle of Pines, St. Thomas, and
<br />The Birds of North America, No. 25, 1992
<br />Anegada (Hancock and Kushlan 1984). Formerly
<br />in Jamaica (Spendelow and Patton 1988).
<br />Winter range. Pacific coast south of 61 °N
<br />(Williamson et a1.1965) through Central America,
<br />and mostly south of Canada and midwest U.S.
<br />states (Fig. 1). Includes the islands and coast of the
<br />Caribbean south to Colombia (Hancock and
<br />Kushlan 1984).
<br />RANGE OUTSIDE AOU CHECK -LIST REGION
<br />Great Blue Heron breeds on the Galapagos
<br />Islands (Harris 1973), Great White Heron on islands
<br />near Venezuela (Hancock and Kushlan 1984).
<br />Former casual in winter in Venezuela and
<br />Colombia (Byrd 1978, Hancock and Kushlan 1984);
<br />stragglers recorded on Hawaiian Islands (Berger
<br />1972).
<br />FOSSIL HISTORY
<br />Large herons referable to the living genus Ardea
<br />have been in existence since the middle Miocene
<br />and probably before, although the phylogenetic
<br />relationships of fossil species to living species is
<br />still not clear.
<br />Earliest record for Ardea is an undescribed
<br />species from the early Barstovian North American
<br />Land Mammal Age (NALMA: 14 million yr before
<br />present) from Observation Quarry, Dawes Co.,
<br />NB, about the size of the Great Egret (Casmerodias
<br />albus; Becker 1986). Next record for Ardea sp. from
<br />the late Clarendonian NALMA (10 mybp) from
<br />Love Bone Bed, Alachua Co., FL, the size of A. h.
<br />occidentalis (Becker 1985b). Ardea polkensis Brodkorb
<br />(1955:17), the only correctly named fossil species
<br />within the geographic range of the living species
<br />(Olson 1985: 165-168), from the late Hemphillian
<br />NALMA (5 mybp; Bone Valley, Polk Co., FL); was
<br />smaller thanA. herod ias. A late Blancan NALMA (2
<br />mybp) Ardea sp. record, recently made by Emslie
<br />(1992) from the Macasphalt Shell Pit, Sarasota Co.,
<br />FL, was slightly smaller than female herodias and
<br />equal in size to the White- necked Heron, A. cocoi.
<br />Fossils of A. herodias recorded from many
<br />Pleistocene (1.8 mybp) and prehistoric sites within
<br />the U.S. (see Becker 1982: 449,1984: 203, 1985a: 38,
<br />also Brodkorb 1963: 284, Guthrie 1992: 321,
<br />Parmelee 1977: 200, 1985: 176, Howard 1969),
<br />Mexico (Hamblin and Rea 1985), and St. Croix in
<br />the West Indies (Wetmore 1937).
<br />SYSTEMATICS
<br />The Great Blue Heron has two close relatives, the
<br />South American Cocoi Heron (A. cocoi) and the
<br />Old World Grey Heron. These three taxa are highly
<br />similar morphologically (Bock 1956), behaviorally
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