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Overview

Brief Summary

Description

At over a metre and half in height, the great blue heron is the largest heron in North America and one of the continent's most recognisable wading birds (2) (3). There are two main colour morphs of this statuesque species: a dark form that is mostly blue-grey, with chestnut thighs, and a white cap over a black eye stripe that merges into long, black plumes; and a light form which is all white. The neck, legs and wings are characteristically long, the tail is short, and the yellowish bill is thick, elongate and tapered. In flight, it coils its neck back into a distinctive s-shape, extends its legs back along its body axis, and beats its wings with steady, powerful strokes (2) (3) (4). Although the sexes are similar in appearance, the female is normally around ten percent smaller than the male, while juveniles are duller and lack the long plumes of the adults (4) (5). Considerable uncertainty surrounds the separation of subspecies of the great blue heron, with between two and seven recognised for North America alone (4). However, five main subspecies, that differ in size and plumage and occupy different parts of the species overall range, are commonly referred to: Ardea herodias herodias, A. h. fannini, A. h. wardii, A. h. occidentalis (the white form), and A. h. cognata (2) (4).
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Ardea herodias

The largest heron in North America north of Mexico, the Great Blue Heron is, for the most part, an easy bird to identify. At 42-52 inches, its gray-blue back, buff neck, yellow bill, white face, and long, black facial plumes help to distinguish it from most other waders in its range. The all-white Caribbean subspecies, which enters our area in south Florida, may be distinguished from the similarly-colored Great Egret by its yellow legs and feet. Male and female Great Blue Herons are similar at all times of the year. The Great Blue Heron breeds across the majority of the United States and southern Canada. Great Blue Herons that breed in southern Canada and the northern Great Plains migrate south for the winter, when they may be found in Central America and the Caribbean. Populations living in most of the U.S.are non-migratory. This species is absent from the desert southwest and from high elevations of the Rocky Mountains. Great Blue Herons live in and around small bodies of water. In summer, Great Blue Herons nest in colonies, called ‘rookeries,’ surrounding lakes and ponds. They may nest either in trees, in bushes, or on the ground. This species utilizes similar habitats during the winter. Great Blue Herons mainly eat fish, but may also take crustaceans and small vertebrates (such as frogs, lizards, and mice) when the opportunity arises. Great Blue Herons may be best observed wading in shallow water, where they may be seen plunging their bills into the water to catch fish. It is also possible to see Great Blue Herons at their rookeries, especially when they return to roost at sunset, or while flying with their feet extended and their necks pulled in. Great Blue Herons are primarily active during the day.

Threat Status: Least concern

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Biology

Foraging alone or in flocks, the great blue heron usually hunts by slowly wading or standing motionless in shallow water (2) (4). Although fish form the bulk of its diet, it will also take amphibians, invertebrates, reptiles, mammals and birds. When prey is sighted, it rapidly thrusts its neck forward to snatch the hapless quarry within its bill, and then typically swallows it whole (2) (3). As an alternative to walking or standing, it also occasionally exhibits a range of other foraging techniques that enable it to access deeper water where it is unable to wade. This includes hovering above the water, plunging beneath it, and simply swimming on the surface (4). Generally, the great blue heron nests in tall trees that are near to aquatic feeding areas, and are to some extent isolated from human disturbance (4). However, when trees are not available, it will also nest on the ground in areas free from predators, and in reeds, shrubs and mangroves (2). Although some nest singly, many breed in colonies, which vary in size depending on the amount of nearby foraging habitat (2) (4). Mates and nest sites change from year to year, with the consequence that mate selection is a critical part of the yearly cycle (4). Usually the male secures a display site first, such as an old nest, before engaging in an elaborate courtship display that includes an impressive repertoire of stretching, snapping, twig shaking, crest raising, and circling flight. After forming a pair and mating, the female lays between two to seven pale blue eggs, which are then incubated by both parent birds for around 28 days. The young are fed regurgitated food and fledge the nest after around 60 days (2) (4). The seasonal movements of the great blue heron is very much dependant on its location (3) (4). Herons from north-central North America migrate south over winter, whilst those closer to the either coast are more variable in their movements, with some remaining year round in the same location (2) (4).
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Comprehensive Description

Ardea herodias is a tall, long-necked wading bird of the Order Ciconiiformes (herons and storks), and is the largest of the North American herons. The sexes are similar in this species, with overall body color a dull blue-gray. It has a thick yellow bill, black shoulders, and legs that generally match the body color. A major identifying trait is the white face that has a black streak extending from behind the eye to the back of the head.
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Distribution

Great blue herons can be found in the Nearctic and Neotropical regions. During the spring and summer, they breed throughout North and Central America, the Caribbean, much of Canada and the Galapagos. Some populations migrate to Central and South America during the winter months, but do not breed there. Several small populations breed in the southern hemisphere, including the Galapagos Islands and coastal Venezuela.

Biogeographic Regions: nearctic (Native ); neotropical (Native )

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occurs (regularly, as a native taxon) in multiple nations

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National Distribution

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Breeding

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) BREEDING: southeastern Alaska and southern Canada to southern Mexico, Greater Antilles, Virgin Islands (St. Thomas and Anegada), islands off coastal Venezuela, and on Galapagos. NON-BREEDING: southeastern Alaska, central U.S., and southern New England south to northern South America (mainly to northern Colombia, northern Venezuela). In the U.S. in winter, the highest densities occur along the lower Colorado River, around the Great Salt Lake, and near Aransas National Wildlife Refuge on the Texas coast (Root 1988). Wanders widely outside usual range, a few times to Hawaii. Some subadults may spend summer in nonbreeding range.

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North America
  • North-West Atlantic Ocean species (NWARMS)
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Geographic Range

Great blue herons can be found in Canada, the United States, Central and South America. These birds migrate and may spend different seasons in different regions. During the spring and summer, they breed throughout North and Central America, the Caribbean, southern Canada and the Galapagos Islands. Some populations migrate to Central and South America during the winter months, but do not breed there.

Biogeographic Regions: nearctic (Native ); neotropical (Native )

  • Hancock, J. 1990. The Herons Handbook. London, England: Christopher Helm Publishers Ltd.
  • Terres, J. 1995. The Audubon Society Encyclopedia of North American Birds. New York: Wings Books.
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A. herodias occurs throughout most of North America, including Alaska, Quebec and Nova Scotia. The range extends south through Florida, Mexico and the Caribbean to South America, including the Galapagos Islands. A. herodias is distributed throughout the Indian River Lagoon.
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Range

The great blue heron breeds throughout much of North America, Central America, and on numerous Caribbean Islands, and the Galapagos (4). The subspecies Ardea herodias herodias occurs over most of North America; A. h. fannini occupies the northwest of North America; A. h. wardii is found in the eastern USA, from Kansas to Florida; A. h. occidentalis inhabits extreme southern Florida, the Caribbean and Mexico; and A. h. cognata is restricted to the Galapagos (2) (4).
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Physical Description

Morphology

Great blue herons are the largest herons in North America. They stand approximately 60 cm tall and are 97 to 137 cm long. They weigh 2.1 to 2.5 kg. They have long, rounded wings, long bills that taper to a point at the end, and short tails. They also have very long necks and legs. The bills are a yellowish color and the legs are green. Great blue herons have gray upper bodies, and their necks are streaked with white, black and rust-brown. They have grey feathers on the back of their necks with chestnut colored feathers on their thighs. The males have a puffy plume of feathers behind their heads and also tend to be slightly larger than females.

Range mass: 2100 to 2500 g.

Range length: 97 to 137 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger

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Physical Description

Great blue herons are the largest herons in North America. They stand approximately 60 cm tall and are 97 to 137 cm long. They weigh 2.1 to 2.5 kg. They are tall waterbirds with long, S-shaped necks that have shaggy feathers. They have long, rounded wings, long pointed bills, and short tails. The bills are a yellowish color and the legs are yellowish-green to gray. Great blue herons have gray upper bodies, and their necks are streaked with white, black and rust-brown. They have gray feathers on the back of their necks with chestnut colored feathers on their thighs. They feature a plume of black feathers that starts behind their eyes and extends out behind their heads. Males tend to be slightly larger than females.

Young great blue herons are overall darker in color. They have dark gray crowns and many dark gray streaks on their necks. Young great blue herons do not have plumes on their heads or shaggy neck feathers like adults have.

Range mass: 2.1 to 2.5 kg.

Range length: 97 to 137 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: sexes alike; male larger

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Size

Length: 117 cm

Weight: 2576 grams

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The largest heron in North America, great blue herons attain a height of 38 inches, with a wingspan of 70 inches.
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Ecology

Habitat

Marismas Nacionales-San Blas Mangroves Habitat

This taxon is found in the Marismas Nacionales-San Blas mangroves ecoregion contains the most extensive block of mangrove ecosystem along the Pacific coastal zone of Mexico, comprising around 2000 square kilometres. Mangroves in Nayarit are among the most productive systems of northwest Mexico. These mangroves and their associated wetlands also serve as one of the most important winter habitat for birds in the Pacific coastal zone, by serving about eighty percent of the Pacific migratory shore bird populations.

Although the mangroves grow on flat terrain, the seven rivers that feed the mangroves descend from mountains, which belong to the physiographic province of the Sierra Madre Occidental. The climate varies from temperate-dry to sub-humid in the summer, when the region receives most of its rainfall (more than 1000 millimetres /year).

Red Mangrove (Rhizophora mangle), Black Mangrove (Avicennia germinans), Buttonwood (Conocarpus erectus) and White Mangrove trees (Laguncularia racemosa) occur in this ecoregion. In the northern part of the ecoregion near Teacapán the Black Mangrove tree is dominant; however, in the southern part nearer Agua Brava, White Mangrove dominates. Herbaceous vegetation is rare, but other species that can be found in association with mangrove trees are: Ciruelillo (Phyllanthus elsiae), Guiana-chestnut (Pachira aquatica), and Pond Apple (Annona glabra).

There are are a number of reptiles present, which including a important population of Morelet's Crocodile (Crocodylus moreletii) and American Crocodile (Crocodylus acutus) in the freshwater marshes associated with tropical Cohune Palm (Attalea cohune) forest. Also present in this ecoregion are reptiles such as the Green Iguana (Iguana iguana), Mexican Beaded Lizard (Heloderma horridum) and Yellow Bellied Slider (Trachemys scripta). Four species of endangered sea turtle use the coast of Nayarit for nesting sites including Leatherback Turtle (Dermochelys coriacea), Olive Ridley Turtle (Lepidochelys olivacea), Hawksbill Turtle (Eretmochelys imbricata) and Green Turtle (Chelonia mydas).

A number of mammals are found in the ecoregion, including the Puma (Puma concolor), Ocelot (Leopardus pardalis), Jaguar (Panthera onca), Southern Pygmy Mouse (Baiomys musculus), Saussure's Shrew (Sorex saussurei). In addition many bat taxa are found in the ecoregion, including fruit eating species such as the Pygmy Fruit-eating Bat (Artibeus phaeotis); Aztec Fruit-eating Bat (Artibeus aztecus) and Toltec Fruit-eating Bat (Artibeus toltecus); there are also bat representatives from the genus myotis, such as the Long-legged Myotis (Myotis volans) and the Cinnamon Myotis (M. fortidens).

There are more than 252 species of birds, 40 percent of which are migratory, including 12 migratory ducks and approximately 36 endemic birds, including the Bumblebee Hummingbird, (Atthis heloisa) and the Mexican Woodnymph (Thalurania ridgwayi). Bojórquez considers the mangroves of Nayarit and Sinaloa among the areas of highest concentration of migratory birds. This ecoregion also serves as wintering habitat and as refuge from surrounding habitats during harsh climatic conditions for many species, especially birds; this sheltering effect further elevates the conservation value of this habitat.

Some of the many representative avifauna are Black-bellied Whistling Duck (Dendrocygna autumnalis), Great Blue Heron (Ardea herodias), Roseate Spoonbill (Ajaia ajaja), Snowy Egret (Egretta thula), sanderling (Calidris alba), American Kestrel (Falco sparverius), Blue-winged Teal (Anas discors), Mexican Jacana (Jacana spinosa), Elegant Trogan (Trogan elegans), Summer Tanager (Piranga rubra), White-tailed Hawk (Buteo albicaudatus), Merlin (Falco columbarius), Plain-capped Starthroat (Heliomaster constantii), Painted Bunting (Passerina ciris) and Wood Stork (Mycteria americana).

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Great blue herons always live near sources of water, including rivers, lake edges, marshes, saltwater seacoasts, and swamps. They usually nest in trees or bushes that stand near water, breeding at elevations of up to 1,500 m. They tend to avoid marine habitats along the east coast and instead live inland.

Range elevation: 1500 (high) m.

Habitat Regions: temperate ; tropical ; freshwater

Aquatic Biomes: lakes and ponds; rivers and streams; coastal

Wetlands: marsh ; swamp

Other Habitat Features: riparian

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Habitat and Ecology

Systems
  • Terrestrial
  • Freshwater
  • Marine
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Comments: Freshwater and brackish marshes, along lakes, rivers, bays, lagoons, ocean beaches, mangroves, fields, and meadows. Nests commonly high in trees in swamps and forested areas, less commonly in bushes, or on ground, rock ledges, and coastal cliffs. Often nests with other herons. See Spendelow and Patton (1988) for further details and discussion of geographic variation in nesting sites. Generally nests close to foraging habitat.

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rivers, lake edges, marshes, saltwater shores, and swamps
  • North-West Atlantic Ocean species (NWARMS)
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Great blue herons always live near sources of water, including rivers, lake edges, marshes, saltwater seacoasts, and swamps. They require tall trees near water to nest in, and often nest in groups or "rookeries" which require a stand of suitable trees. They have been found breeding at elevations of up to 1,500 m. Most tend to avoid marine habitats along the east coast and instead live inland.

Range elevation: 1500 (high) m.

Habitat Regions: temperate ; tropical ; freshwater

Aquatic Biomes: lakes and ponds; rivers and streams; coastal

Wetlands: marsh ; swamp

Other Habitat Features: riparian

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Depth range based on 8543 specimens in 1 taxon.
Water temperature and chemistry ranges based on 1 sample.

Environmental ranges
  Depth range (m): 0 - 0
  Temperature range (°C): 15.833 - 15.833
  Nitrate (umol/L): 0.361 - 0.361
  Salinity (PPS): 33.335 - 33.335
  Oxygen (ml/l): 5.746 - 5.746
  Phosphate (umol/l): 0.382 - 0.382
  Silicate (umol/l): 2.546 - 2.546
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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Found in a diverse range of habitats including salt marsh and mangrove swamps, freshwater marshes and swamps, estuaries, coastal lagoons, flooded fields, ditches, riverbanks, and lake edges (4).
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Migration

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.

Migrates to northern breeding range February-early May; departs northerly localities September-October. Disperses in all compass directions after breeding, before southward migration. Southern populations may be quite sedentary. Present in small numbers in Colombia mainly October to mid-April, in Panama mainly September-April (Ridgely and Gwynne 1989, Hilty and Brown 1986).

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Trophic Strategy

Great blue herons fish in both the night and the day, with most of their activity occurring around dawn and dusk. Herons use their long legs to wade in shallow water and their sharp "spearlike" bills to catch their food. Great blue herons' diet consists of mainly fish, but also includes frogs, salamanders, lizards, snakes, birds, small mammals, shrimps, crabs, crayfish , dragonflies, grasshoppers, and many other aquatic insects. Herons locate their food by sight and usually swallow it whole. Herons have been known to choke on prey that is too large.

Animal Foods: birds; mammals; amphibians; reptiles; fish; insects; terrestrial non-insect arthropods; aquatic crustaceans

Primary Diet: carnivore (Piscivore )

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Comments: Eats fishes, insects, crustaceans, amphibians and reptiles, mice and shrews, and other animals. Forages mostly while standing in water but also in fields; sometimes drops from air or perch into water (Palmer 1962, Terres 1980).

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Food Habits

Great blue herons fish primarily during the day or occasionally at night, but most of their activity occurs around dawn and dusk. Herons use their long legs to wade in shallow water and their sharp spear-like bills to catch their food. Great blue herons' diet consists of mainly fish, but also includes frogs, salamanders, lizards, snakes, young birds, small mammals, shrimp, crabs, crayfish, dragonflies, grasshoppers and many aquatic invertebrates. Herons locate their food by sight and usually swallow it whole. Herons have been known to choke on prey that is too large. Great blue herons obtain water by scooping up water with their bills and tipping their heads back to drink. Great blue herons live in aquatic habitats and are surrounded by water for nearly their entire lives.

Animal Foods: birds; mammals; amphibians; reptiles; fish; insects; terrestrial non-insect arthropods; aquatic crustaceans

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As large wading birds, great blue herons are able to feed in deeper waters, and thus are able to exploit a niche not open to most other heron species. Primary feeding behaviors in this species include standing crouched, standing upright, and wading slowly. Great blue herons have high striking efficiency (the percentage of strikes that result in the capture and ingestion of prey) when standing crouched on banks. However, this behavior is used less often than either standing upright or wading slowly. This suggests that the goal for great blue herons may not be achieving maximum feeding efficiency; but rather, maximizing food intake through the infrequent capture of high quality prey (Willard 1977). Data seem to reinforce this point, as it has been shown that great blue herons that utilize the rather inefficient slow wade as a feeding strategy tend to feed upon more large fish such as eel and perch (Willard 1977).In a Canadian study of great blue herons, Butler (1993) found that A. herodias fed primarily upon sticklebacks, shiners, sea perch, pipefish, sculpins, etc., and that they require approximately 30% more energy above basal metabolic costs to fuel their activities.Activity Time: Butler (1993) stated that the nocturnal feeding behavior observed in great blue herons was important to resource partitioning and reduced competition among wading birds. In a Cedar Key, Florida study, Black and Collopy (1982) found great blue herons to be equally active in either daylight or evening hours, though most evening feeding occurs during early evening low tides than later in the evening.
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Associations

Great blue herons control fish and insect populations in many different habitats. They are also an important source of food for the animals that prey on them.

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Northwest crows and common ravens have been reported eating heron eggs. Eagles, racoons, bears, turkey vultures, and red-tailed hawks prey on the young birds and sometimes even the adults. Birds will abandon a colony where they have been living after a predator has killed an adult or chick in the area.

Known Predators:

  • crows and ravens
  • common raven
  • eagles
  • raccoons
  • bears
  • turkey vulture
  • red-tailed hawks

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Ecosystem Roles

Great blue herons control fish and insect populations in many different habitats. They are also an important source of food for the animals that prey on them.

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Predation

Corvus caurinus and Corvus corax have been reported eating heron eggs. Eagles, Procyon lotor, bears, Cathartes aurata, and Buteo jamaicensis prey on the young birds and sometimes even the adults. Birds often abandon a rookery where they have been living after a predator has killed an adult or chick in the area.

Nesting in rookeries is a way for great blue herons to avoid predation. If a heron nests within a large group, there are many more eyes and ears to keep watch for predators. Also, the chances that one particular nest will be predated decreases significantly when there is a high density of nests.

Known Predators:

  • Northwest crows (Corvus_caurinus)
  • Common raven (Corvus_corax)
  • Eagles
  • Raccoons (Procyon_lotor)
  • Bears
  • Turkey vultures (Cathartes_aura)
  • Red-tailed hawks (Buteo_jamaicensis)

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A. herodias is generally considered a solitary feeder, though it has been observed to associate with other wading birds of various sizes while feeding. While breeding, A. herodias avoids mixed flocks in favor of nesting in monospecific colonies.
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Known prey organisms

Ardea herodias preys on:
Paralichthyes albigutta
Strongylura marina
Leiostomus xanthurus
Cyprinus carpio
Carassius auratus
Pimephales notatus
Lepomis macrochirus
Pseudacris triseriata
Chelydra serpentina

Based on studies in:
USA: Florida (Estuarine)

This list may not be complete but is based on published studies.
  • Christian RR, Luczkovich JJ (1999) Organizing and understanding a winter’s seagrass foodweb network through effective trophic levels. Ecol Model 117:99–124
  • Myers, P., R. Espinosa, C. S. Parr, T. Jones, G. S. Hammond, and T. A. Dewey. 2006. The Animal Diversity Web (online). Accessed February 16, 2011 at http://animaldiversity.org. http://www.animaldiversity.org
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Population Biology

Number of Occurrences

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: > 300

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The great blue heron is generally the most well known and widespread heron species in North America. It is common throughout the Indian River Lagoon.
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General Ecology

Nonbreeding: usually solitary. May establish feeding territories in winter (Stiles and Skutch 1989).

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Life History and Behavior

Behavior

Great blue herons are relatively quiet compared to other related species. They release a soft "kraak" when they are disturbed in flight. Other heron calls include a "fraunk" when they are disturbed near their nests which usually lasts about 20 seconds, and an "ar" when they are greeting other members of their species. These herons are known to have up to 7 different calls. They also snap their bills together and use complicated body movements in courtship displays.

Communication Channels: visual ; acoustic

Perception Channels: visual ; tactile ; acoustic ; chemical

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Diet

fish, frogs, salamanders, lizards, snakes, shrimps, crabs, crayfish, dragonflies, grasshoppers, and many aquatic insects
  • North-West Atlantic Ocean species (NWARMS)
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Communication and Perception

Great blue herons are relatively quiet compared to other related species. Their main call is a soft "kraak" when they are disturbed in flight. Other heron calls include a "fraunk" when they are disturbed near their nests which usually lasts about 20 seconds, and an "ar" when they are greeting other members of their species. These herons are known to have up to 7 different calls. They also snap their bills together, raise their feathers, and shake twigs in courtship displays.

Communication Channels: visual ; acoustic

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Cyclicity

Comments: Generally tends to be mainly crepuscular but also is active in daytime and at night. In coastal region, activity often is related to the tidal cycle, independent of day-night cycle in some areas (Powell 1987). Nocturnal foraging activity occurs in nontidal situations as well as in tidal environments (McNeil et al. 1993).

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Life Expectancy

The oldest wild great blue heron was said to be 23 years old, but most do not live so long. The average lifespan for a great blue heron is around 15 years. As with most animals, they are most vulnerable when they are young. More than half (69%) of the great blue herons born in one year will die before they are a year old.

Range lifespan

Status: wild:
24.5 (high) years.

Average lifespan

Status: wild:
15 years.

Average lifespan

Status: wild:
294 months.

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Lifespan/Longevity

The oldest wild great blue heron was said to be 23 years old, but most do not live so long. The average lifespan for a great blue heron is around 15 years. As with most animals, they are most vulnerable when they are young. More than half of the great blue herons born in one year will die before they are a year old.

Range lifespan

Status: wild:
24.5 (high) years.

Average lifespan

Status: wild:
15 years.

Average lifespan

Status: wild:
294 months.

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Lifespan, longevity, and ageing

Maximum longevity: 24.5 years (wild)
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Reproduction

Great blue herons generally have one mate per breeding season.

Mating System: monogamous

Great blue herons typically breed from March to May in the northern part of their range and November through April in the southern part of their range. Females lay between 2 and 7 pale blue eggs. Birds living further north tend to have more eggs. Both parents incubate the eggs, which means that the parents take turns sitting on the nest to keep the eggs warm until they hatch. The eggs hatch after 26 to 30 days of incubation. After living in the nest for about 2 months, the babies (called chicks) are ready to fledge, which means they are old enough to leave the nest and survive on their own. Herons become sexually mature when they are about 22 months of age.

Breeding interval: Great blue herons breed once yearly.

Breeding season: Breeding occurs from March to May in northern parts of their range and November to April in southern parts of their range.

Range eggs per season: 2 to 7.

Range time to hatching: 30 (high) days.

Average time to hatching: 27 days.

Range fledging age: 60 to 81 days.

Average age at sexual or reproductive maturity (female): 22 months.

Average age at sexual or reproductive maturity (male): 22 months.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous

Average eggs per season: 4.

Both parents care for and feed the chicks until they are ready to leave the nest. The largest chicks receive the most food.

Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female)

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Clutch size is 3-7, averages larger in north than in south. Incubation, by both sexes, lasts 25-29 days. Both parents tend young, which leave nest in 60-90 days. May breed at 2 years. Nests usually in colonies, a few pairs to 100s; sometimes solitary. Fledging success depends importantly on success of parents in providing sufficient food when nestlings are 2-6 weeks old (Bennett et al. 1995, Auk 112:201-209).

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Great blue herons generally have one mate per breeding season. Males will perform courtship displays to attract a female. A male will perch at his nest, stretch his neck and fluff his plume of neck feathers. He may also fly in a circle around his nest or shake twigs to impress a female. Once he gets the attention of a potential mate, she perches next to the male and they will both raise their crest feathers and clatter their beaks together. Pairs may repeat these behaviors throughout the breeding season.

Mating System: monogamous

Great blue herons use large nests mainly of bare sticks and branches. These herons prefer to nest in tall trees and most nests are built 9 to 21 m off the ground. Great blue herons often nest in large groups, or rookeries, with other herons.

Great blue herons typically breed from March to May in the northern part of their range and November through April in the southern hemisphere. Females lay between 2 and 7 pale-blue eggs. Both parents take turns incubating the eggs, which hatch after 26 to 30 days. After living in the nest for about 2 months, the chicks are ready to fledge, which means they are old enough to leave the nest and survive on their own. Herons are usually old enough to reproduce when they are about 22 months old.

Breeding interval: Great blue herons breed once yearly.

Breeding season: Breeding occurs from March to May in northern parts of their range and November to April in southern parts of their range.

Range eggs per season: 2 to 7.

Average eggs per season: 3 to 5.

Range time to hatching: 26 to 30 days.

Range fledging age: 56 to 60 days.

Average age at sexual or reproductive maturity (female): 22 months.

Average age at sexual or reproductive maturity (male): 22 months.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)

Average eggs per season: 4.

Both great blue heron parents care for the young. Males and females build a stick nest, high in a tree. Parents take turns incubating the eggs, and after the eggs have hatched they will take turns caring for the chicks. The young herons are born helpless and rely on their parents for warmth, protection, and food. Chicks are fed mostly fish.

Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female)

  • Ehrlich, P., D. Dobkin, D. Wheye. 1988. The Birder's Handbook: A Field Guide to the Natural History of North American Birds. New York, NY: Simon & Schuster Inc.
  • Hancock, J. 1990. The Herons Handbook. London, England: Christopher Helm Publishers Ltd.
  • Terres, J. 1995. The Audubon Society Encyclopedia of North American Birds. New York: Wings Books.
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Though sympatric with other species of wading birds, the great blue heron forms monospecific breeding colonies. This behavior differs from species such as the snowy egret and white ibis that nest in large mixed flocks. Colony size in great blue herons can be large, ranging between 5 - 500 nests per colony, with an average of approximately 160 nests per colony.Nesting in the Florida Everglades and Lake Okeechobee begins between late November through mid-March and April, with nests sometimes located as high as 20 m above the ground (Butler 1993; Smith 1997). Clutch size ranges from 3 - 6 eggs, with 1 brood being raised each year. Should eggs be abandoned or destroyed, a replacement clutch can be laid (Ehrlich et al. 1988).Reproductive success in great blue herons is limited by the ability of parent birds to gather food. Energy availability (as measured in food resources) appears, in part, to determine when eggs will be laid. Butler (1993) observed that egg laying in great blue herons occurs after a threshold level for successful egg laying is surpassed for several consecutive days. Chicks are generally present after parental food availability peaks. This leads to a potential problem in nourishing nestlings. Parental birds have been shown to consume up to 4 times as much food when they are feeding young chicks than when egg laying or incubating eggs (Butler 1993); however, chicks do not reach their metabolic peak until approximately 26 - 41 days after birth. Thus, if food availability has already peaked before chicks appear, it is then potentially more difficult for parents to nourish nestlings. There is some data to support this view. Collazo (1981) found that starvation was not only the primary cause of nestling mortality, but that it most often coincided with the peak energy demands of 3 - 6 week old chicks.A. herodias is negatively affected by human disturbance, particularly during the early stages of the breeding cycle. Repeated human intrusion into nesting areas often results in nest failure, with abandonment of eggs or chicks (Carlson and McLean 1996). Great blue herons thus tend to choose nest sites in undisturbed wetland areas around lakes or rivers, well removed from roads (Gibbs and Kinkel 1997) and other signs of human activity. In one Ohio study, foot traffic was observed to be the most detrimental disruption to breeding great blue herons, sometimes leading to nest abandonment. Nesting birds were shown to tolerate routine mechanical disturbance, even if loud, as long as no humans were nearby (Carlson and McLean 1996). Nest success increased when nest sites were chosen near barriers such as fencing, ditches or moats that excluded human intrusion. Nests located in areas with this type of buffer zone, even if small in overall area, had higher nest success and fledging rates than those located near disturbed areas.
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Growth

Eggs are incubated for approximately 28 days and hatch asynchronously over a period of several days (Custer and Peterson 1991). The first chick to hatch becomes more experienced in food handling and aggressive interactions with siblings, and so often grows at a faster rate than its nestmates. Male and female chicks show little difference in hatching weight, but males tend to grow somewhat faster than females. By the time fledging occurs, males often weigh up to 13% more than females. Young fledge after 56 - 60 days (Ehrlich et al. 1988).
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Molecular Biology and Genetics

Molecular Biology

Barcode data: Ardea herodias

The following is a representative barcode sequence, the centroid of all available sequences for this species.


There are 4 barcode sequences available from BOLD and GenBank.

Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.

See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNCCGGCATAATTGGAACCGCCCTAAGCCTACTCATCCGAGCTGAACTTGGGCAACCAGGGACACTCCTAGGAGACGACCAGATCTACAATGTGATTGTTACTGCTCATGCCTTCGTAATAATCTTTTTTATAGTAATACCGATCATAATCGGAGGATTCGGAAATTGACTAGTCCCACTCATAATTGGTGCCCCAGACATAGCATTTCCGCGCATGAATAATATAAGCTTCTGACTTCTCCCGCCATCATTCATGCTTCTTCTAGCCTCATCCACAGTTGAAGCAGGAGCAGGTACAGGCTGAACAGTTTACCCCCCATTAGCTGGTAATCTAGCTCATGCCGGAGCTTCAGTAGACCTAGCTATCTTCTCCCTCCACCTAGCGGGTGTATCCTCTATCCTAGGGGCAATTAACTTCATCACAACCGCCATCAACATAAAACCCCCAGCCCTATCACAGTATCAAACTCCCTTATTCGTGTGATCCGTCCTAATTACTGCCGTCCTACTCCTACTCTCACTTCCAGTCCTCGCCGCAGGCATCACAATACTACTAACTGATCGAAACCTAAACACCACATTCTTTGACCCTGCCGGAGGCGGAGACCCAGTCCTCTACCAACATCTCTTCTGATTCTTTGGCCACCCAGAAGTCTACATCCTAATTCTC
-- end --

Download FASTA File

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Statistics of barcoding coverage: Ardea herodias

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 4
Specimens with Barcodes: 9
Species With Barcodes: 1
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Conservation

Conservation Status

This is the most well-known and most widespread heron in North America. Human interference with the heron primarily involves destruction of habitat. Many herons are also killed each year due to collisions with utility wires. Great blue herons are protected by the United States Migratory Bird Treaty Act.

US Migratory Bird Act: protected

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

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IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2012

Assessor/s
BirdLife International

Reviewer/s
Butchart, S. & Symes, A.

Contributor/s

Justification
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be increasing, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size may be small, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
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National NatureServe Conservation Status

Canada

Rounded National Status Rank: N5B - Secure

United States

Rounded National Status Rank: N5B,N5N : N5B: Secure - Breeding, N5N: Secure - Nonbreeding

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NatureServe Conservation Status

Rounded Global Status Rank: G5 - Secure

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This is the most well-known and most widespread heron in North America. Human interference with the heron primarily involves destruction of habitat. Many herons are also killed each year due to collisions with utility wires. As a migratory species, great blue herons are protected by the United States Migratory Bird Treaty Act. Great blue herons have no special protection in the state of Michigan since their populations are large and healthy.

IUCN Red List of Threatened Species: least concern

US Migratory Bird Act: protected

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

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Status

Classified as Least Concern (LC) on the IUCN Red List (1).
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Population

Population Trend
Increasing
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Global Short Term Trend: Relatively stable (=10% change)

Comments: Populations generally are stable or increasing in most areas. See Spendelow and Patton (1988) for status of coastal U.S. breeding populations. Populations in the south-central U.S. may be benefiting from crayfish aquaculture; bird population increases may be related to favorable foraging opportunities afforded by expanding crayfish aquaculture (herons may prey on small fishes often abundant in ponds) (Fleury and Sherry 1995).

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Threats

Comments: In Illinois, a public viewing area used once a week by humans 229 m from a rookery did not cause any overt responses from nesting birds (DeMauro 1993). See Vos (1984) for information on response to human disturbance in Colorado.

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Great blue herons are among the most well known and most common of the wading bird species. It is not federally listed as either threatened or endangered, nor is it listed in Florida as a Species of Special Concern (SSC).Benefit in IRL: The environmental sensitivity of wading birds, coupled with the relative ease of assessing their numbers, makes them attractive as biological indicators of ecosystem health and habitat quality (Custer and Osborn 1977; Powell and Powell 1986; Powell et al. 1989).
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The great blue heron has a remarkable ability to exploit a wide range of habitats and food types. Consequently it is widespread and abundant, and is not subject to any major threats at the species level (4) (6). Nonetheless, some populations, particularly those occupying small areas on the coast, are vulnerable to localised impacts (4). This broadly includes habitat destruction, human disturbance and persecution, and contamination by pollutants (2) (4).
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Management

Conservation

Critical to the conservation of threatened populations of the great blue heron is the protection of nesting sites and feeding habitats, and the conservation of food supplies (2) (4). This is already being achieved by initiatives such as the Heron Working Group, the primary goal of which is to ensure a viable and self-sustaining population of the Pacific great blue heron (A. h. fannini) (7).
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Relevance to Humans and Ecosystems

Benefits

People who create and stock fish ponds may find that their expensive fish are being eaten by great blue herons. This can be prevented by installing bird netting or using decoy herons to scare the birds away.

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Great blue herons are a delight to watch and are important members of healthy, freshwater ecosystems.

Positive Impacts: ecotourism

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Economic Importance for Humans: Negative

People who create and stock fish ponds may find that their expensive fish are being eaten by great blue herons. This can be prevented by installing bird netting or using decoy herons to scare the birds away.

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Economic Importance for Humans: Positive

Great blue herons are a delight to watch and are important members of healthy, freshwater ecosystems.

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Wikipedia

Great blue heron

This article is about the bird. For the Music Festival, see The Great Blue Heron Music Festival.

The great blue heron (Ardea herodias) is a large wading bird in the heron family Ardeidae, common near the shores of open water and in wetlands over most of North America and Central America as well as the Caribbean and the Galápagos Islands. It is a rare vagrant to Europe, with records from Spain, the Azores, England and the Netherlands. An all-white population found only in the Caribbean and southern Florida was once treated as a separate species and known as the great white heron.

Taxonomy[edit]

The great blue heron was one of the many species originally described by Carolus Linnaeus in his 18th century work, Systema Naturae.[2]

The great blue heron is replaced in the Old World by the very similar grey heron (Ardea cinerea), which differs in being somewhat smaller (90–98 cm (35–39 in)), with a pale gray neck and legs, lacking the browner colors that great blue heron has there. It forms a superspecies with this and also with the cocoi heron from South America, which differs in having more extensive black on the head, and a white breast and neck.

There are five subspecies:[3]

  • Ardea herodias herodias Linnaeus, 1758. Most of North America, except as below.
  • Ardea herodias fannini Chapman, 1901. The Pacific Northwest from southern Alaska south to Washington; coastal.
  • Ardea herodias wardi Ridgway, 1882. Kansas and Oklahoma to northern Florida. Sightings in southeastern Georgia have occurred.
  • Ardea herodias occidentalis Audubon, 1835. Southern Florida, Caribbean islands. Formerly known as a separate species, the great white heron.
  • Ardea herodias cognata Bangs, 1903. Galápagos Islands.

Description[edit]

It is the largest North American heron and, among all extant herons, it is surpassed only by the Goliath heron (Ardea goliath) and the white-bellied heron (Ardea insignis). It has head-to-tail length of 91–137 cm (36–54 in), a wingspan of 167–201 cm (66–79 in), a height of 115–138 cm (45–54 in), and a weight of 1.82–3.6 kg (4.0–7.9 lb).[4][5][6][7] In British Columbia, adult males averaged 2.48 kg (5.5 lb) and adult females 2.11 kg (4.7 lb).[8] In Nova Scotia and New England, adult herons of both sexes averaged 2.23 kg (4.9 lb),[9] while in Oregon both sexes averaged 2.09 kg (4.6 lb)[10] Thus, great blue herons are roughly twice as heavy as great egrets (Ardea alba), although only slightly taller than them, but can themselves weigh about half as much as a large Goliath heron.[11] Notable features of great blue herons include slaty (gray with a slight azure blue) flight feathers, red-brown thighs, and a paired red-brown and black stripe up the flanks; the neck is rusty-gray, with black and white streaking down the front; the head is paler, with a nearly white face, and a pair of black or slate plumes running from just above the eye to the back of the head. The feathers on the lower neck are long and plume-like; it also has plumes on the lower back at the start of the breeding season. The bill is dull yellowish, becoming orange briefly at the start of the breeding season, and the lower legs gray, also becoming orangey at the start of the breeding season. Immature birds are duller in color, with a dull blackish-gray crown, and the flank pattern only weakly defined; they have no plumes, and the bill is dull gray-yellow.[3][12][13] Among standard measurements, the wing chord is 43–49.2 cm (16.9–19.4 in), the tail is 15.2–19.5 cm (6.0–7.7 in), the culmen is 12.3–15.2 cm (4.8–6.0 in) and the tarsus is 15.7–21 cm (6.2–8.3 in).[14][15]

The heron stride is around 22 cm (8.7 in), almost in a straight line. Two of the three front toes are generally closer together. In a track the front toes as well as the back often show the small talons.[16]

The subspecies differ only slightly in size and plumage tone, with the exception of subspecies occidentalis, which as well as normal colored birds, also has a distinct white morph, known as the great white heron (not to be confused with the great egret, for which "great white heron" was once a common name). It is found only in south Florida and some parts of the Caribbean. The great white heron differs from other great blues in bill morphology, head plume length, and in having a total lack of pigment in its plumage. It averages somewhat larger than the sympatric race Ardea herodias wardi and may be the largest race in the species. In a survey of A. h. occidentalis in Florida, males were found to average 3.02 kg (6.7 lb) and females average 2.57 kg (5.7 lb), with a range for both sexes of 2 to 3.39 kg (4.4 to 7.5 lb).[4] This is mainly found near salt water, and was long thought to be a separate species. Birds intermediate between the normal morph and the white morph are known as Würdemann's heron; these birds resemble a "normal" great blue with a white head.

The theory that great white heron may be a separate species (A. occidentalis) from great blue heron has again been given some support by David Sibley.[17]

Voice[edit]

Their call is a harsh croak. The heron is most vocal during the breeding season, but will call occasionally at any time of the year in territorial disputes or if disturbed.

Four calls of the great blue heron

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Nonvocal sounds include a loud bill snap, which males use to attract a female or to defend a nest site and which females use in response to bachelor males or within breeding pairs.[18] The bill snap may be analogous the territorial song of passerines.[18] Bill clappering, the rapid chattering of the tips of the bill, is very common between paired herons.[18]

Similar species[edit]

The "great white heron" could be confused with great egret but is larger, with yellow legs as opposed to the great egret's black legs. The reddish egret (Egretta rufescens) and little blue heron (Egretta caerulea) could be mistaken for the great blue heron, but are much smaller, and lack white on the head and yellow in the bill. In the southern reaches of its range, the great blue sometimes overlaps in range with the closely related and similarly sized cocoi heron (Ardea cocoi). The cocoi is distinguished by a striking white neck and solid black crown, but the duller juveniles are more easily confused. More superficially similar is the slightly smaller grey heron, which may sometimes vagrate to the Northern coasts of North America. The grey heron (which occupies the same ecological niche in Eurasia as the great blue heron) has very similar plumage but has a solidly soft-gray neck. Erroneously, the great blue heron is sometimes referred to as a "crane".

Distribution and habitat[edit]

Flying with nesting material in Illinois, USA

The great blue heron is found throughout most of North America, as far north as Alaska and the southern Canadian provinces. The range extends south through Florida, Mexico and the Caribbean to South America. Birds east of the Rocky Mountains in the northern part of their range are migratory and winter in Central America or northern South America. From the southern United States southwards, and on the Pacific coast, they are year-round residents.[3] However their hardiness is such that individuals often remain through cold northern winters, as well, so long as fish-bearing waters remain unfrozen (which may be the case only in flowing water such as streams, creeks and rivers).

The great blue heron can adapt to almost any wetland habitat in its range. They may be found in numbers in fresh and saltwater marshes, mangrove swamps, flooded meadows, lake edges, or shorelines. They are quite adaptable and may be seen in heavily developed areas as long as they hold bodies of water bearing fish. Great blue herons rarely venture far from bodies of water but are occasionally seen flying over upland areas. They usually nest in trees or bushes near water's edge, often on island (which minimizes the potential for predation) or partially isolated spots.[19]

It has been recorded as a vagrant in England,[20] Greenland, Hawaii, and the Azores.[3]

Behavior[edit]

Diet[edit]

Eating a small fish, the main prey.
On a slow-flying glide

The primary food for great blue heron is small fish, though it is also known to opportunistically feed on a wide range of shrimp, crabs, aquatic insects, rodents and other small mammals, amphibians, reptiles, and small birds. Primary prey is variable based on availability and abundance. In Nova Scotia, 98% of the diet was flounders.[9] In British Columbia, the primary prey species are sticklebacks, gunnels, sculpins and perch.[21] Californian herons were found to live mostly on sculpin, bass, perch, flounder and top smelt.[22] Non-piscivore prey is rarely quantitatively important, though one study in Idaho showed that from 24 to 40% of the diet was made up of voles.[23]

Herons locate their food by sight and usually swallow it whole. Herons have been known to choke on prey that is too large.[24][25] It is generally a solitary feeder. Individuals usually forage while standing in water but will also feed in fields or drop from the air, or a perch, into water. Mice are occasionally predated in upland areas far from the species' typical aquatic environment.[19] Occasionally loose feeding flocks form and may be beneficial since they are able to locate schools of fish more easily.[19] As large wading birds, great blue herons are capable of feeding in deeper waters and thus are able to harvest from niche areas not open to most other heron species. Typically, the great blue heron feeds in shallow waters, usually less than 50 cm (20 in) deep,[19] or at the water's edge during both the night and the day, but especially around dawn and dusk. The most commonly employed hunting technique of the species is wading slowly with its long legs through shallow water and quickly spearing fish or frogs with its long, sharp bill. Although usually ponderous in movements, the great blue heron is adaptable in its fishing methods. Feeding behaviors variably have consisted of standing in one place, probing, pecking, walking at slow speeds, moving quickly, flying short distances and alighting, hovering over water and picking up prey, diving headfirst into the water, alighting on water feet-first, jumping from perches feet-first, and swimming or floating on the surface of the water.[19]

Breeding[edit]

At the nest

This species usually breeds in colonies, in trees close to lakes or other wetlands. Adults generally return to the colony site after winter from December (in warmer climes such as California and Florida) to March (in cooler areas such as Canada). Usually colonies include only great blue herons though sometimes they nest alongside other species of herons. These groups are called heronry (a more specific term than "rookery"). The size of these colonies may be large, ranging between 5–500 nests per colony, with an average of approximately 160 nests per colony. Heronry are usually relatively close, usually within 4 to 5 km (2.5 to 3.1 mi), to ideal feeding spots.[19] Heronry sites are usually difficult to reach on foot (e.g., islands, trees in swamps, high branches, etc.) in order to protect from potential mammalian predators. Trees of any type are used when available. When not, herons may nest on the ground, sagebrush, cacti, channel markers, artificial platforms, beaver mounds and duck blinds. Other waterbirds (especially smaller herons) and, occasionally, even fish and mammal-eating raptors may nest amongst colonies.[26][27] Although nests are often reused for many years and herons are socially monogamous within a single breeding season, individuals usually choose new mates each year.[18] Males arrive at colonies first and settle on nests, where they court females; most males choose a different nest each year.[18] Great blue herons build a bulky stick nest. Nests are usually around 50 cm (20 in) across when first constructed, but can grow to more than 120 cm (47 in) in width and 90 cm (35 in) deep with repeated use and additional construction.[28] If the nest is abandoned or destroyed, the female may lay a replacement clutch. Reproduction is negatively affected by human disturbance, particularly during the beginning of nesting. Repeated human intrusion into nesting areas often results in nest failure, with abandonment of eggs or chicks.

The female lays three to six pale blue eggs. Eggs can measure from 50.7 to 76.5 mm (2.00 to 3.01 in) in length and 29 to 50.5 mm (1.14 to 1.99 in) in width, though the smallest eggs in the above sample may have been consider "runt eggs" too small to produce viable young. Egg weigh range from 61 to 80 g (2.2 to 2.8 oz).[29] One brood is raised each year. First broods are laid generally from March to April.[30][31] Eggs are usually laid at 2 day intervals, incubated for around 27 days and hatch asynchronously over a period of several days.[18] Males incubate for about 10.5 hours of each day while females usually incubate for the remainder of each day and the night, with eggs left without incubation for about 6 minutes of each hour.[18] The first chick to hatch usually becomes more experienced in food handling and aggressive interactions with siblings, and so often grows more quickly than the other chicks.[32] Both parents feed the young at the nest by regurgitating food. Parent birds have been shown to consume up to four times as much food when they are feeding young chicks (about 4300 kJ/day) than when laying or incubating eggs (about 1200 kJ/day).[18] By the time they are 45 days old, the young weigh 86% of the adult's mass.[33] After about 55 days at the northern edge of the range (Alberta) and 80 days at the southern edge of the range (California), young herons take their first flight.[18] They will return to the nest to be fed for about another 3 weeks, following adults back from foraging grounds and are likely to gradually disperse away from their original nest over the course of the ensuing winter.[18] Young herons are not as successful at fish capture as adults, as strike rates are similar but capture rates about half that of adults during the first 2 months post-fledging.[18]

Predation[edit]

Predators of eggs and nestlings include turkey vultures (Cathartes aura), common ravens (Corvus corax) and American crows (Corvus brachyrhynchos). Red-tailed hawks (Buteo jamaicensis), American black bears (Ursus americanus) and raccoons (Procyon lotor) are known to take larger nestlings or fledglings and, in the latter predator, many eggs.[8][34][35][36] Adult herons, due to their size, have few natural predators, but a few of the larger avian predators have been known to kill both young and adults, including bald eagles (Haliaeetus leucocephalus) (the only predator known to attack great blue herons at every stage of their life-cycle from in the egg to adulthood), golden eagles (Aquila chrysaetos) and, less frequently, great horned owls (Bubo virginianus) and Harris's hawks (Parabuteo unicinctus).[37][38][39][40][41] An occasional adult or, more likely, an unsteady fledgling may be predaceously snatched by an American alligator (Alligator mississippiensis) or an American crocodile (Crocodylus acutus). Using their considerable size and dagger-like bill, a full-grown heron can be a formidable foe to a predator. In one instance, during an act of attempted predation by a golden eagle, a heron was able to mortally wound the eagle although itself succumbed to injures sustained in the fight.[42] When predation on an adult or chick occurs at a breeding colony, the colony can be abandoned by the other birds, but this does not always occur. The primary source of disturbance and breeding failures at heronries is human activities, mostly through human recreation or habitat destruction, as well as by egg-collectors and hunters.[21][43]

In art[edit]

John James Audubon illustrates the great blue heron in Birds of America, Second Edition (published, London 1827–38) as Plate 161. The image was engraved and colored by Robert Havell's, London workshops. The original watercolor by Audubon was purchased by the New-York Historical Society where it remains to this day (January 2009).

Gallery[edit]


References[edit]

  1. ^ BirdLife International (2012). "Ardea herodias". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013. 
  2. ^ Linnaeus, C (1758). Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata. (in Latin). Holmiae. (Laurentii Salvii). p. 105. 
  3. ^ a b c d del Hoyo, J., Elliott, A., & Sargatal, J., eds. (1992). Handbook of the Birds of the World Vol. 1. Lynx Edicions, Barcelona ISBN 84-87334-10-5.
  4. ^ a b CRC Handbook of Avian Body Masses, 2nd Edition by John B. Dunning Jr. (Editor). CRC Press (2008), ISBN 978-1-4200-6444-5.
  5. ^ del Hoyo, J; Elliot, A; Sargatal, J (1996). Handbook of the Birds of the World 3. Barcelona: Lynx Edicions. ISBN 84-87334-20-2. 
  6. ^ Cornell Lab of Ornithology
  7. ^ Great Blue Herons, Great Blue Heron Pictures, Great Blue Heron Facts – National Geographic. Animals.nationalgeographic.com (2012-12-13). Retrieved on 2012-12-19.
  8. ^ a b Simpson, K. 1984. Factors affecting reproduction in Great Blue Herons (Ardea herodias). Master's Thesis. Univ. Brit. Col. Vancouver.
  9. ^ a b Quinney, T. E. and P. C. Smith. 1979. Reproductive success, growth of nestlings and foraging behaviour of the Great Blue Heron (Ardea herodias herodias L.). contract rept. No. KL229-5-7077. Can. Wildl. Serv. Ottawa.
  10. ^ Bayer, R. D. (1981). Arrival and departure frequencies of Great Blue Herons at two Oregon estuarine colonies. The Auk, 589-595.
  11. ^ CRC Handbook of Avian Body Masses by John B. Dunning Jr. (Editor). CRC Press (1992), ISBN 978-0-8493-4258-5.
  12. ^ Sibley, D. (2000). The Sibley Guide to Birds. National Audubon Society ISBN 0-679-45122-6
  13. ^ Dickinson, M. B. et al., eds. (1999). Field Guide to the Birds of North America. National Geographic ISBN 0-7922-7451-2.
  14. ^ Blake, Emmett Reid (1977). Manual of Neotropical Birds, Volume 1. University Of Chicago Press, ISBN 978-0-226-05641-8
  15. ^ Proceedings of the United States National Museum, Volume 42.
  16. ^ Murie & Elbroch, Peterson Field Guide to Animal Tracks, pg. 334 (2005)
  17. ^ Sibley, D. A. "Great White" Heron – not just a colour morph (retrieved 2009-01-24)
  18. ^ a b c d e f g h i j k Butler RW. The Great Blue Heron. In Birds of North America (ed: Poole and Gill), No. 25
  19. ^ a b c d e f Short, Henry L. and Cooper, Robert J. (1985). Habitat suitability index models Great blue heron. Biological report 82(10.99). Washington, DC : Western Energy and Land Use Team, Division of Biological Services, Research and Development, Fish and Wildlife Service
  20. ^ "Heron in UK, 3K miles off target. Thesun.co.uk (2007-12-11). Retrieved on 2012-12-19.
  21. ^ a b Butler, R. 1991. Habitat selection and time of breeding in the Great Blue Heron (Ardea herodias). Phd Thesis. Univ. of Brit. Col. Vancouver.
  22. ^ Hom, C. W. 1983. Foraging ecology of herons in a southern San Francisco Bay saltmarsh. Colonial Waterbirds 6:37-44.
  23. ^ Collazo, J. A. 1979. Breeding biology and food habits of the Great Blue Heron at Heyburn State Park, Benewah County, Idaho. Master's Thesis. Univ. Idaho, Moscow.
  24. ^ "Hinterland Who's Who – Great Blue Heron". Canadian Wildlife Service. Retrieved 2007-11-23. 
  25. ^ Wolf, B. O. and S. L. Jones. 1989. Great Blue Heron deaths caused by predation on Pacific lamprey. Condor 91:482–484.
  26. ^ Custer, T. W., R. G. Osborn, and W. F. Stout. 1980. Distribution, species abundance, and nesting-site use of Atlantic Coast colonies of herons and their allies. Auk 97:591-600.
  27. ^ Ryser, Jr., F. A. 1985. Birds of the Great Basin. Univ. Nevada Press, Reno.
  28. ^ Andrle, R. F. 1988. The atlas of breeding birds in New York State. Cornell Univ. Press, Ithaca, New York.
  29. ^ Bent, A. C. 1926. Life histories of North American marsh birds. U.S. Natl. Mus. Bull. 135.
  30. ^ Brandman, M. 1976. A quantitative analysis of the annual cycle of behavior in the Great Blue Heron (Ardea herodias). Phd Thesis. Univ. Calif. Los Angeles.
  31. ^ Vermeer, K. 1969. Great Blue Heron colonies in Alberta. Can. Field-Nat. 83:237-242.
  32. ^ Naumann, Robert. (2000-05-16) Animaldiversity.ummz.umich.edu. Animaldiversity.ummz.umich.edu. Retrieved on 2012-12-19.
  33. ^ Quinney, T. E. 1982. Growth, diet, and mortality of nestling Great Blue Herons. Wilson Bull. 94:571-577.
  34. ^ Lopinot, A. C. 1952. Raccoon predation on Great Blue Herons. Auk 68:235.
  35. ^ Hjertaas, D. G. 1982. Great Blue Herons and raccoons at Nicolle Flats. Blue Jay 40:36-41.
  36. ^ Foss, E. 1980. A black bear in a Great Blue Heron colony. Murrelet 61:113.
  37. ^ Forbes, L. S. 1987. Predation on Great Blue Herons: is it important?. Colonial Waterbirds 10:120-122.
  38. ^ Kelsall, J. P. and K. Simpson. 1980. A three-year study of the Great Blue Heron in southwestern British Columbia. Proc. Colonial Waterbird Grp. 3:69-74.
  39. ^ Olendorff, R. R. (1976). The food habits of North American golden eagles. American Midland Naturalist, 231-236.
  40. ^ Houston, C. Stuart, Dwight G. Smith and Christoph Rohner. 1998. Great Horned Owl (Bubo virginianus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/372
  41. ^ Woodward, H. D., & Trussell, R. W. (2003). Lone Harris's Hawk kills Great Blue Heron. JOURNAL OF RAPTOR RESEARCH, 37(1), 85-86.
  42. ^ Santy, D. 1964. A recollection of an encounter between a Golden Eagle and a Great Blue Heron. Blue Jay, 22: 55.
  43. ^ Simpson, K., J. N. M. Smith, and J. P. Kelsall. 1987. Correlates and consequences of coloniality in Great Blue Herons. Can. J. Zool. 65:572-577.
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Names and Taxonomy

Taxonomy

Comments: Includes great white heron, formerly considered a distinct species, A. OCCIDENTALIS. Some authors consider A. HERODIAS, A. CINEREA, and A. COCOI conspecific (AOU 1983); the three constitute a superspecies (Butler 1992).

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