Egretta caerulealittle blue heron

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Geographic Range

The Little Blue Heron is found along the Atlantic coast from Massachusetts to Florida, but is most abundant along the Gulf of Mexico. It also nests in the West Indies, and along both Mexican coasts through Central America and into South America. Its range can also extend into the Amazon Basin, the Caribbean, and the more northern regions of North America. (Riegner 1998)

Habitat

Although Egretta caerulea often lives near saltwater, it is mainly an inland bird. They prefer freshwater areas such as ponds, lakes, marshes, swamps, and lagoons, but also sometimes occupy flooded and dry grasslands, or marine coastlines. (Riegner 1998, Terres 1980, Tarski 2001)

Physical Description

The Little Blue Heron is a small, dark bird that ranges from 63-74 centimeters in length. It can have a wingspread of up to 1.04 meters. The sexes look similar, but the young look very different from the adults. An adult can be recognized by its purple-maroon head and neck. The rest of the plumage is slate gray. The long neck is usually held in an "S" shaped curve while the bird is at rest or in flight. The heron's long, slender bill curves slightly downward, and is also dark gray but has a black tip. The eyes are yellow and the legs and feet are dark. The young are unlike any other heron because they have all white body plumage. They have a blue bill with a black tip and dull green legs. They stay white through their first summer, fall, and into winter, but start molting in February into the dark color of an adult. (Terres 1980; Tarski 2001)

  • Average mass
    396 g
    13.96 oz
  • Average mass
    215.6 g
    7.60 oz
    AnAge

Reproduction

The pale, blue-green eggs of the Little Blue Heron are laid in April. They can lay from 3-5 eggs, but on average lay 4-5. This process takes 5-8 days, with one egg being laid every other day. Both sexes incubate the eggs until they hatch in 22-24 days, and then quickly remove the eggshells from the nest. It may take about 5 days for all of the chicks to emerge. Although the young can raise their heads, they spend most of their time lying on the nest floor. Both parents feed them by dropping food into the nest and later placing it directly into the chicks' mouths. In about 3 weeks, the young are ready to leave the nest for short trips along surrounding branches. When they are 30 days old, they are able to fly and periodically leave the nest area. Soon after, at 42-49 days, the young are on their own. Little Blue Herons can breed when they are one year old. They have been recorded as living more than 7 years in the wild. (Riegner 1998, Terres 1980, Katusic 1998)

  • Average eggs per season
    4
    AnAge
  • Average time to hatching
    23 days
    AnAge

Lifespan/Longevity

Behavior

The flight of Egretta caerulea is graceful and strong. Their wing strokes are quicker than that of larger herons, and they fly with their head down and legs extended to the rear. They are usually silent, but sometimes make a low clucking or croaking sound. Their sounds during fighting are much different and resemble the screams of parrots.

Little Blue Herons are not energetic birds. They will sometimes walk quickly or even run, but are usually seen walking slowly and daintily along marshes. While hunting, these birds are loners, but nest together in small or large colonies.

Prior to mating, males stretch their necks upward with the bill pointing up, and then assume a crouched posture. Their movements include bill snapping, vocalizing, and neck swaying. If a female is impressed, she will approach him. Their first encounter can be very aggressive but, after a while, this is replaced with signs of affection such as feather nibbling and neck crossing. The male then gathers sticks to present to the female, raising his plumes and nibbling her feathers as she places the sticks into a nest structure. The flimsy nest is usually built up to 3-4.5 meters above the ground or water, but can be as high as 12 meters. (Riegner 1998, Terres 1980)

Communication and Perception

Food Habits

Egretta caerulea feed mainly during the daylight hours. They are carnivorous, with their diet consisting of fish, frogs, lizards, snakes, turtles, and crustaceans such as fiddler crabs, crayfish and shrimp. They also eat aquatic insects and spiders. When swamps and marshes become dry, they live on grasshhoppers, crickets, beetles and other grassland insects.

The Little Blue Heron's long legs enable it to wade into the water, where it walks slowly along an area in order to locate prey, often retracing its steps or standing motionless. They sometimes rake the ground with their foot to disturb prey into movement and stretch their long necks to peer into the water. Their long beak is used to jab and eat the prey. Extensive studies found the heron's prey capture success rate to be about 60 percent. (Terres 1980, Riegner 1998)

Economic Importance for Humans: Positive

The Little Blue Heron is enjoyable to watch and helps control insect populations. (Riegner 1998)

Economic Importance for Humans: Negative

The Little Blue Heron has no negative affect on humans.

Conservation Status

The major problem facing these birds is the loss of their wetland habitats. Little Blue Herons need clean, undisturbed wetlands for feeding and breeding. Colonies are being lost because of clear cutting of forests, and draining of ponds, lakes, and wetlands. The use of pesticides has also caused eggshell thinning. The population has been decreasing and the Little Blue Heron is considered threatened and of special concern in some coastal areas. (Katusic 1998, Riegner 1998)

Other Comments

The Little Blue Heron is sometimes referred to as the blue crane, levee walker, or little blue crane.

They have a commensal relationship with White Ibises (Eudocimus albus). The ibises stir up food as they walk, increasing the number of prey available to the Little Blue Herons. The herons benefit, while the ibises are unaffected. (Riegner 1998, Terres 1980)

Contributors

Kate Thome (author), Milford High School, George Campbell (editor), Milford High School.

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.

chemical

uses smells or other chemicals to communicate

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.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

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).

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.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scrub forest

scrub forests develop in areas that experience dry seasons.

sexual

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

tactile

uses touch to communicate

visual

uses sight to communicate

References

Katusic, P. 1998. "Little Blue Heron" (On-line). Accessed January 27, 2001 at http://www.inhs.uiuc.edu/chf/pub/ifwis/birds/little-blue-heron.html.

Riegner, M. 1998. "Birder's World: Slow-walking heron" (On-line). Accessed February 24, 2001 at http://www.findarticles.com/cf_0/m0FZU/n4_v12/20889817/p1/article.jhtml?term=.

Tarski, C. 2001. "Birding/Wild Birds" (On-line). Accessed January 27,2001 at http://birding.about.com/hobbies/birding/library/fg/blfg-egrettacaerulea.htm.

Terres, J. 1980. The Audubon Society Encyclopedia of North American Birds. New York: Alfred A. Knopf.