Great Blue Heron

Ardea herodias Linnaeus

 

 

 

Field Guide IDs:
NG-62; G-94; P~l00; PW-pl 4; All-pl 14; AW-pl 15; AM (1)-108


Nest
Location
Nest
Type
Eggs &
Mating System
Dev. &
Parental Care
Primary &
2ndary Diet
..
Foraging
Strategy
MF
I: 28 DAYS
SEMIALTRICIAL 1
30 feet - 70 feet
(10 feet -130 feet)
MF
3-5
(1-7)
MONOG
F: 56-60 DAYS
MF
AQUATIC INVERTS
SM VERTS


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.

STANFORD. NOTES:

Uncommon visitor throughout the year. Occasionally forages at Lagunita, and for voles and pocket gophers in grassy areas throughout campus &endash; including the median along Campus Drive.

ESSAYS:

Piracy; Variation in Clutch Sizes; Blue List; Coloniality

REFERENCES:

Gibbs et al., 1987; Hancock and Kushlan, 1984; Pratt and Winkler, 1985.