Egretta tricolortricolored heron(Also: Louisiana heron)

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Geographic Range

These herons are found in eastern and southern North America (along coast of Maine, through Texas and along both coasts of Mexico), Central America (coastal areas), the West Indies, and coastal South America to the mouth of the Amazon river in Brazil on the Atlantic coast, and to northern Peru on the Pacific coast.

Habitat

The tricolored heron is a "...bird of shallow marshes and shores, using mudflats, mangrove swamps and bays" (Hancock & Kushman, 1984). They often prefer mangroves, swamps of freshwater and the outskirts of rivers to live in. There have been exceptions found to these habitat areas; tricolored heron colonies have been found living on dry ground and still others at high altitudes. (Hancock and Kushlan, 1984)

Physical Description

Tricolored herons are medium-sized birds with the long legs and neck characteristic of herons and egrets. Legs are yellow in the non-breeding season and pink in the breeding season. In flight and at rest Egretta tricolor holds its neck at a curve, similar to a "S". They have a rather long and pointed bill that, in the non-breeding season, is yellow with a black tip. In the breeding season, the yellow turns to blue. Their underside and neck is a white, a characteristic that is unique to this particular species, but makes them very difficult to find because they blend into the vegetation in their habitat.

The young are differently colored than the adults and have a "rich chestnut head and neck...and chestnut feathering on blue-gray back" (Robbins, et al., 1966).

Mass: 415g = males, 334g = females (Robbins, et al., 1966)

  • Sexual Dimorphism
  • male larger
  • Range length
    25 to 30 cm
    9.84 to 11.81 in
  • Average wingspan
    38 cm
    14.96 in

Reproduction

The male chooses the nesting site before mating with the female. The female lays eggs on a nest constructed of "...sticks placed on a bed of reeds or in a tree" which the female and male build together. ()

Tricolored Herons begin nesting in early to mid-March and tend to make their nest when the water in their habitat has receded. This tendency seems to exist because "low water levels help to concentrate prey in a small area, thereby making it simpler for parent birds to feed nestlings" (Hill, 2001). When the water is low the parents do not have to go far to find food for their newly hatched young and can minimize their energy requirements during this important time when they need to concentrate on the success of their offspring. Receded water also helps in the foraging success of the offspring so that they can easily find food when they are young. Female Tricolored Herons lay approximately 3-4 bluish eggs per clutch, with one clutch per year.

The chicks of the Egretta tricolor hatch over a several day period making the first chick to hatch more experienced at food foraging and aggressive encounters with other chicks in his/her brood. Therefore the first chick to hatch has an advantage over its nestmates and often has a better survival rate compared with the other chicks.

The female Egretta tricolor lays, on average, 3-4 bluish colored eggs once a year. She lays one egg every other day. Both the female and male Tricolored Heron take turns sitting on the nest. The young hatch after a 3 week incubation period, several days apart from one another. The parents bring food to the young and allow the young to forage near the nesting site. The young are ready to fly at about 35 days of age and then go off on their own, since adults are mostly solitary.

As in all wading birds, nest success can be greatly compromised by cold weather, predation, and water levels that have not receded.

  • Breeding season
    begin nesting in early to mid-March
  • Range eggs per season
    3 to 4
  • Range time to hatching
    21 to 25 days
  • Average fledging age
    35 days

Both the male and female care for the young after they hatch. The parents gather food which they regurgitate for their offspring. The chicks fledge in about 35 days after hatching and go off on their own.

Lifespan/Longevity

Tricolored herons may live as long as 17 years in the wild.

Behavior

Tricolored Herons are migratory birds. North American populations have been documented to "...winter into Colombia and Ecuador" (Kushlan & Hafner, 2000). During the post-breeding season Egretta tricolor disperses "...into the south-central USA" (Kushlan & Hafner, 2000).

Egretta tricolor is very defensive about its hunting area and will charge at other invading Tricolored Herons and other wading bird species (Gobien, 2001).

Communication and Perception

Food Habits

Tricolored herons usually stand in shallow water to find and catch prey. The bird has many different types of prey-catching behaviors. Hancock and Kushlan call their most frequent form of prey catching behavior a "walk-quickly-running-open wing tactile sequence" (Hancock & Kushlan, 1984). Egretta tricolor's prey catching behavior is varied depending on the habitat in which they live, but almost all their food is found in shallow waters. Unlike other heron species which change their diet depending on changing environmental conditions, the tricolored heron changes "...their foraging habitats and feeding strategies in order to continue to encounter preferred prey items" (Hill, 2001).

Ninety percent of the diet of Egretta tricolor is composed of fish. It also eats "...amphibians, crustaceans, gastropods, leeches, worms, spiders, and insects..." (Hancock & Elliott, 1978). (Hancock and Elliott, 1978; Hancock and Kushlan, 1984; Hill, 2001)

  • Animal Foods
  • amphibians
  • fish
  • insects
  • terrestrial non-insect arthropods
  • mollusks
  • aquatic or marine worms

Predation

Tricolored herons, especially pairs, fight off any predators. I found no predator information specifically regarding the tricolored heron, so the following are predators of herons in general: raccoons, crows and ravens will eat eggs and nestlings, and owls will feed on adults as well as young. Turkey vultures will come and eat any leftovers, since they feed on dead animals

(Hill, 2001).

Ecosystem Roles

Since many wading birds are environmentally sensitive, including the Tricolored Heron, they make good indicator species. In looking at a number of conditions of wading birds, including containment accumulation in chicks, trace elements in feathers, eggshell thickness and quality, genetic damage, deformities, time of nesting, mortality, clutch size, hatching and fledging success, and growth rates of young, scientists and researchers can evaluate the health of the ecosystem and the quality of the habitat in which these birds live (Kushlan & Hafner, 2000). (Hancock, 2000; Rattner, et al., 2001)

Economic Importance for Humans: Positive

Egretta tricolor eats insects, including mosquitos, that are irritating pests to humans. They are also a biological indicator which will help determine if other species in the habitat are healthy or are in danger due to enviornmental conditions. This directly effects humans in that many species of fish that live in the same habitats as tricolored herons are frequently eaten by humans and are an economically important food source.

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

There are no known adverse effects of Egretta tricolor on humans.

Conservation Status

The populations of Tricolored Herons seem to have remained stable or increased in all of their habitats in the United States except for Texas and southern Florida (Kushlan & Hafner, 2000). (Kushlan and Hafner, 2000)

Other Comments

The tricolored heron is also known as the Louisiana Heron.

Egretta tricolor has relatively large populations in North America compared to other heron species. This may in part reflect that hatmakers, who killed many herons for their feathers, were never interested in the tricolored heron's feathers. (The Assateague Naturalist, 1997)

Contributors

Nicole LaLonde (author), University of Michigan-Ann Arbor, Kerry Yurewicz (editor), University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

brackish water

areas with salty water, usually in coastal marshes and estuaries.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

estuarine

an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.

female parental care

parental care is carried out by females

fertilization

union of egg and spermatozoan

freshwater

mainly lives in water that is not salty.

internal fertilization

fertilization takes place within the female's body

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

male parental care

parental care is carried out by males

marsh

marshes are wetland areas often dominated by grasses and reeds.

migratory

makes seasonal movements between breeding and wintering grounds

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

piscivore

an animal that mainly eats fish

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

young precocial

young are relatively well-developed when born

References

Gobien, A. 2004. "Bird: Tricolored (Louisiana) Heron (Egretta tricolor)" (On-line). The Birds of Wakodahatchee. Accessed 03/10/02 at http://www.pbcwater.com/wakodahatchee/Tricolored_Heron.htm.

Hancock, J. 2000. Herons of the World: Their World in Focus. San Diego, CA: Academic Press.

Hancock, J., H. Elliott. 1978. The Herons of the World. New York: Harper and Row Publishers.

Hancock, J., J. Kushlan. 1984. The Herons Handbook. New York: Harper and Row Publishers.

Hill, A. 1996. "Hunting Strategies" (On-line). Accessed 03/20/2002 at http://www.sfgate.com/getoutside/1996/may/hunting.html.

Hill, K. 2001. "Species Report: Egretta tricolor" (On-line). Smithsonian Marine Station at Fort Pierce. Accessed 03/10/02 at http://www.sms.si.edu/IRLSpec/Egretta_Tricol.htm.

Kushlan, J., H. Hafner. 2000. Heron Conservation. London: Academic Press.

National Audubon Society North Carolina Sanctuaries, 2000. "Tricolored Heron" (On-line). Colonial Waterbirds of North Carolina. Accessed 03/10/02 at http://www.audubon.org/chapter/nc/nc/wb_17.html.

Rattner, B., N. Golden, J. Cohen, L. Garrett, R. Erwin, M. Ottinger, J. Pearson. 2001. "Tricolored Heron" (On-line). Biological and Ecotoxicological Characteristics of Terrestrial Vertebrates. Accessed 03/10/2002 at http://www.pwrc.usgs.gov/bioeco/.

Robbins, C., B. Bruun, B. Zim. 1966. Birds of North America. New York: Western Publishing Company, Inc..

Tarski, C. 2002. "Tricolored Heron, Egretta Tricolor" (On-line). Virtual Field Guide to Birds. Accessed 03/10/02 at http://birding.about.com/library/fg/blfg-egrettatricolor.htm.

The Assateague Naturalist, 1997. "Tricolored Heron (Egretta tricolor)" (On-line). Birds of Assateague. Accessed 03/15/02 at http://www.assateague.com/tri-her.html.