Green Heron Life History

Habitat

Habitat MarshesGreen Herons are common breeders in coastal and inland wetlands. They nest along swamps, marshes, lakes, ponds, impoundments, and other wet habitats with trees and shrubs to provide secluded nest sites. They may even nest in dry woods and orchards as long as there is water nearby for foraging. Green Herons spend the winter in southern coastal areas of their range, and in marine and freshwater habitat throughout Mexico and Central America. In tropical areas they are common in mangrove swamps.Back to top

Food

Food FishGreen Herons eat mainly small fish such as minnows, sunfish, catfish, pickerel, carp, perch, gobies, shad, silverside, eels, and goldfish. They also feeds on insects, spiders, crustaceans, snails, amphibians, reptiles, and rodents. They hunt by standing still at the water’s edge, in vegetation, or by walking slowly in shallow water. When a fish approaches, the heron lunges and darts its head, grasping (or sometimes spearing) the fish with its heavy bill. Occasionally Green Herons hunt in deeper water by plunging on prey from above. They hunt at all times of the day and night in the shallows of swamps, creeks, marshes, ditches, ponds, and mangroves. They usually forage among thick vegetation in water that is less than 4 inches deep, avoiding the deeper and more open areas frequented by longer-legged herons.Back to top

Nesting

Nest Placement

Nest TreeThe male selects a secluded site within his territory, usually in a large fork of a tree or bush, with overhanging branches to conceal the nest. Green Herons use many plant species as nest sites pines, oaks, willows, box elder, cedar, honey locust, hickory, sassafrass, and mangroves. The nest is usually on or over the water, but may be up to a half-mile away. It may be anywhere from ground level to 30 feet off the ground (occasionally higher).

Nest Description

The male begins building the nest before pairing up to breed, but afterward passes off most of the construction to his mate. As the male gathers long, thin sticks, the female shapes them into a nest 8–12 inches across, with a shallow depression averaging less than 2 inches deep. The nest varies from solid to flimsy, and has no lining. Green Herons sometimes renovate old nests, or build in old nests of Black-crowned Night-Herons or Snowy Egrets. Occasionally they take sticks from nearby old nests and refashion them into new nests. They keep adding sticks throughout the breeding season.

Nesting Facts
Clutch Size:3-5 eggs
Number of Broods:1-2 broods
Egg Length:1.3-1.7 in (3.4-4.3 cm)
Egg Width:1.1-1.4 in (2.7-3.5 cm)
Incubation Period:19-21 days
Nestling Period:16-17 days
Egg Description:Pale green to bluish.
Condition at Hatching:Mostly helpless, but with open eyes. Covered with grayish brown down on top and white down beneath.
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Behavior

Behavior StalkingEach breeding season, Green Herons pair up with one mate apiece, performing courtship displays that include stretching their necks, snapping their bills, flying with exaggerated flaps, and calling loudly. They often nest solitarily, although they may join colonies with other Green Herons or with other species. They defend breeding areas from each other and from birds like crows and grackles that prey on their nests. Other predators include snakes and raccoons. Both the male and female brood and feed the chicks, which may stay with their parents for more than a month after leaving the nest, as they learn to forage. Green Herons protect their feeding areas by driving away other species, such as American Coots, that approach too closely.Back to top

Conservation

Conservation Common Bird in Steep DeclineGreen Herons are still common, but their population suffered a gradual decline of over 1.5% per year from 1966 to 2014, resulting in a cumulative decline of 68%, according to the North American Breeding Bird Survey. The North American Waterbird Conservation Plan rates Green Heron as a Species of Low Concern, and rates it a 12 out of 20 on the Continental Concern Score. Green Heron is not listed on the 2014 State of the Birds Report. Declines have been recorded across most of the heron's range, with only California populations showing an increase in that time. Green Herons can be found throughout the year across the U.S. (with the exception of several mid-western states), Central and northern South America. A small percentage breeds in the southwest of Canada. In the past, people hunted Green Herons for food and controlled their numbers near fish hatcheries, where the herons were perceived as a threat to the fish. Today, their biggest threat is probably habitat loss through the draining or development of wetlands, although no one knows the extent of this impact because these herons are solitary and widely dispersed.Back to top

Backyard Tips

Green Herons sometimes pay visits to ornamental fish ponds. A length of drain pipe placed in the pond can provide fish with a place to hide from feeding herons.

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Credits

Davis Jr., William E. and James A. Kushlan. 1994. Green Heron (Butorides virescens), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Kushlan, J. A., M. J. Steinkamp, K. C. Parsons, J. Capp, M. A. Cruz, M. Coulter, I. Davidson, L. Dickson, N. Edelson, R. Elliott, R. M. Erwin, S. Hatch, S. Kress, R. Milko, S. Miller, K. Mills, R. Paul, R. Phillips, J. E. Saliva, W. Sydeman, J. Trapp, J. Wheeler and K. Wohl. 2002. Waterbird conservation for the Americas: The North American waterbird conservation plan, version 1. Washington, D.C.: Waterbird Conservation for the Americas.

Lutmerding, J. A. and A. S. Love. Longevity records of North American birds. Version 2015.2. Patuxent Wildlife Research Center, Bird Banding Laboratory 2015.

North American Bird Conservation Initiative. 2014. The State of the Birds 2014 Report. US Department of Interior, Washington, DC, USA.

Sauer, J. R., J. E. Hines, J. E. Fallon, K. L. Pardieck, Jr. Ziolkowski, D. J. and W. A. Link. The North American Breeding Bird Survey, results and analysis 1966-2013 (Version 1.30.15). USGS Patuxtent Wildlife Research Center 2014b. Available from http://www.mbr-pwrc.usgs.gov/bbs/.

Sibley, David Allen. 2014. The Sibley guide to birds, second edition. Alfred A Knopf, New York.

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