Great Blue Heron (Ardea herodias)
Great Blue Heron Ardea herodias
46 inches (117 cm) W 72 inches (183 cm)
• Gray-blue overall
• White head with black stripe above eye
• Front of neck white with black vertical streak
• Breeding adult: Yellow bill and long neck plumes
• Sexes similar
• Huge, long-legged, long-necked wader
• Usually holds neck in an "S" curve at rest and in flight
• Long, thick, yellow bill
• White crown and face
• Black plume extending from above and behind eye to beyond back of head
• Brownish-buff neck with black-bordered white stripe down center of foreneck
• Blue-gray back, wings and belly
• Black shoulder
• Shaggy neck and back plumes in breeding plumage
• Black cap
• Brownish-gray back and upperwings
• Lacks shaggy neck and back plumes
• Lacks black plume extending from behind eye
"Great White Heron":
• White morph of Great Blue Heron
• Large yellow bill
• Yellow legs
• White plumage
• Single white plume extending back from above eye
• Found only in South Florida, rarely north along the coast
• Tricolored Heron has white belly. Reddish Egret and Little Blue Heron are smaller, and lack white on head and yellow in bill. "Great White Heron" could be confused with Great Egret but is larger, with yellow legs and the single head plume coming from behind the eye.
Common in river and lake edges, wet meadows, freshwater marshes, swamps, fields and other wetland environments. Also tidal mudflats, sandbars and mangroves. Hunts by remaining motionless in shallow water and waiting for prey to come within striking distance. Flies with distinctive slow, labored wingbeats, trailing legs behind and head folded back on shoulders. Wary. May perch in trees. Most active just before dawn and at dusk.
NESTING & FEEDING:
BREEDING: Freshwater and brackish marshes, swamps, lakes, rivers, mangroves. 1 brood. Mating system is monogamous.
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 occasionally 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. Both sexes help with nest construction.
EGGS: Light bluish-green. 2.5" (64 mm).
CHICK DEVELOPMENT: Both sexes incubate. Incubation takes 28 days. Development is semialtricial (immobile, downy, eyes open, fed). Young are able to fly after 56-60 days. Both sexes tend young.
DIET: Mostly fish, but opportunistic, including human food scraps, nestlings, small mammals. Young fed fish.
CONSERVATION: Winters s to n South America. Blue List 1980-81, Special Concern1982, Local Concern 1986; numbers increasing but much Atlantic coast habitat gone.
NOTES: Nests in colonies, variable in size, occasionally 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 twice as successful as young, which expend far more energy in foraging. White morphs ("Great White Heron") found only in marine habitats.
Ardea herodias GREAT BLUE HERON. Marshes, lakes, swamps, rivers, lagoons, coasts, mangroves.
Populations in the Caribbean are polymorphic and the white morph was formerly treated as a separate species, A. occidentalis, the Great White Heron, now usually considered a race of herodias, as below. The name "Great White Heron" would be appropriate for Ardea alba which is called the Great Egret and was formerly placed in Casmerodius; see below.
A. h. herodias. From coastal sc,se Alaska, coastal and se British Columbia, w,e Washington, w,s Idaho, n,se Utah, wc,nc New Mexico, c Colorado, wc Montana, se,sc Alberta, c Saskatchewan, c Manitoba, c Ontario, s Quebec, New Brunswick, Prince Edward Island and Nova Scotia s through U.S. (exc. Central Valley and se deserts of Calif.). Nw Mexico to Sinaloa and on Atlantic slope locally from Tamaulipas to Yucatán Peninsula; Galapagos Islands. Winters from se Alaska, coastal British Columbia and U.S. s through C. America and W. Indies to nw South America and Galapagos Is., rarely to Hawaiian Islands. Ranges to 2600 m in tropics and subtropics.
A. h. occidentalis. GREAT WHITE HERON. S coastal Florida, Florida Keys, Cuba, I. of Pines, Virgin Is. on St. Thomas and Anegada; coast of Yucatán Pen., and I. Los Roques off n Venezuela. Winters s to n coastal Venezuela, rarely to s Atlantic and Gulf coasts of the U.S.