BofS-Great Blue Heron

		Great Blue Heron Ardea herodias
STANFORD LOCATIONS: Uncommon visitor throughout the year. Occasionally forages at Lagunita, and for voles and pocket gophers in grassy areas throughout campus--including the median along Campus Drive.

BREEDING:	Freshwater and brackish marshes, swamps, lakes, rivers, mangroves. 1 brood.
DISPLAYS:	Male at nest: neck stretch and fluff, circle flight, twig shake. Pair: crest raising, bill clappering. Displays more varied than those of egrets, but used less often and continue after pair-bond formation.
NEST:	Also occ in shrub, rarely on ground, rock ledge, coastal cliff. Large, flat, well made of interwoven sticks. Lined with twigs and leaves; repaired nests often lined with green needles.
EGGS:	Light bluish-green. 2.5" (64 mm).
DIET:	Mostly fish, but opportunistic, including human food scraps, nestlings, small mammals. Young fed fish.
CONSERVATION:	Winters s to n S.A. Blue List 1980-81, Special Concern 1982, Local Concern 1986; numbers increasing but much Atlantic coast habitat gone.
NOTES:	Nests in colonies, variable in size, occ solitary; in mixed colonies, Great Blue nests higher. Average clutch size increases with latitude to 5 in s Canada. As in most herons, foraging success improves with age: adults 2x as successful as young, which expend far more energy in foraging. White morphs ("Great White Heron") found only in marine habitats.
ESSAYS:	Piracy; Variation in Clutch Sizes; Blue List; Coloniality.
REFERENCES:	Gibbs et al., 1987; Hancock and Kushlan, 1984; Pratt and Winkler, 1985.

Help	Abbreviations	Species-Alphabetical	Species-Taxonomic	Essays-Alphabetical	Essays-Categorized
Except for Stanford Locations, the material in this species treatment is taken, with permission, from The Birder's Handbook (Paul Ehrlich, David Dobkin, & Darryl Wheye, Simon & Schuster, NY. 1988).