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Eudocimus ruberscarlet ibis

By Katherine Phelps

Geographic Range

Eudocimus ruber is found in northern South America, stretching from Venezuela to Eastern Brazil. It is nomadic, with seasonal shifts and migrations between different coastal locations and interior wetlands. ("Scarlet Ibis", 2001; Hancock, et al., 1992)

Habitat

Eudocimus ruber prefers swampy environments such as mud flats and shallow bays. It tends to reproduce and nest on dense brush-covered islands and mangroves near the mouths of rivers. ("Scarlet Ibis", 2001)

Physical Description

Eudocimus ruber is in the same family as spoonbills. Ibises have slightly webbed feet and a thin, down-curved bill. They fly with the bill forward and neck held straight. All ibises are long-legged and long-necked wading birds, but E. ruber can be characterized by its stunning red plumage and its glossy blue-black wing tips. This bright red color fades to pink in captive zoo birds, unless they are given a specific diet, which consists of high levels of protein and shrimp meat. Although the adults are brightly colored, the young are dull, with a grayish-brown color and white underbellies. Females and males are identical in coloration, but the male's body size and bill length are much larger. Scarlet ibises weigh between 0.772 to 0.935 g, are 55.8 to 76.2 cm long and have wingspans of 52.1 to 56.1 cm. Their metabolic rate can reach 1432 cm^3 oxygen/hour. (Hancock, et al., 1992; "Ibis", 2001; "Scarlet Ibis", 2001)

  • Sexual Dimorphism
  • sexes alike
  • male larger
  • Average mass
    615 g
    21.67 oz
    AnAge
  • Average length
    55.8-76.2 cm
    in
  • Average wingspan
    52.1-56.1 cm
    in
  • Range basal metabolic rate
    1432 (high) cm3.O2/g/hr

Reproduction

Eudocimus ruber has a colonial and social breeding system. Nests are generally built close to one another with more than one per tree. This is most likely done to reduce the risks of predation. Males use displays of preening, flights, head rubbing, and a rocking motion to attract mates. A female must be cautious when approaching a male, because he may actually attack her if she does not remain in his display area. Scarlet ibises are polygynous, the males often mate with more than one female. (Hancock, et al., 1992; Olmos and Silva, 2001; "Scarlet Ibis", 2001)

Eudocimus ruber begins visiting its colonial nesting sites by mid-September, egg-laying takes place between early November through December. The first egg is laid 5 to 6 days after copulation and there are usually 3 to 5 eggs in each nest. Eggs are not glossy, but are smooth. Incubation lasts between 19 to 23 days. Chicks fledge after 35 days and are independent in 75 days. (Hancock, et al., 1992; Olmos and Silva, 2001)

  • Breeding interval
    Breeding occurs once yearly
  • Breeding season
    Typically breeding occurs from September through December
  • Range eggs per season
    3 to 5
  • Average eggs per season
    2
    AnAge
  • Range time to hatching
    19 to 23 days
  • Average fledging age
    35 days
  • Average time to independence
    75 days

Young E. ruber are altricial, when they first hatch, they are helpless and cannot even hold up their heads. Both adult birds share in the responsibilities of caring for and tending to the young. Both incubate, provide food and also guard against predators. To feed their chicks adults grab hold of the bill of the young bird, which causes it to raise its head so that the parent can regurgitate into the mouth. The chick's feet develop quite fast; this allows the chicks to fledge as early as 2 weeks. By 40 days old, the young are able to fly well and by 75 days old, they are able to provide for themselves and can leave the colony. (Hancock, et al., 1992; Olmos and Silva, 2001)

  • Parental Investment
  • no parental involvement
  • altricial
  • pre-hatching/birth
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • male
      • female

Lifespan/Longevity

Young E. ruber have approximately a 50% mortality rate. In general, colonies suffer from high mortality rates due to predation and lack of food. Although information on actual lifespan of E. ruber is limited, data on its North American relative, Eudocimus albus, can be used as an adequate estimate. Eudocimus albus usually lives for about 16 years in the wild and 20 years in captivity; the oldest known captive individual lived 31 years. (Hancock, et al., 1992; Hill, 2001; Ricklefs, 2000)

  • Average lifespan
    Status: captivity
    33.2 years
    AnAge

Behavior

Eudocimus ruber is a highly communal species. It is social both during nesting and when searching for food. Eudocimus ruber will fly in large flocks between different feeding and roosting sites. In flight, the birds will soar and also glide at great heights and speeds. If disturbed, sometimes all the birds of a nesting area will take flight at once. Territorial disputes between males are settled by size. (Hancock, et al., 1992)

Home Range

The range for E. ruber is varied and extensive, because of nomadic movements between nesting and foraging sites. Shifts occur between the interior wetlands of northern South America to coastal locations. More specifically, birds forage between the higher and lower llanos of South America. Nesting then takes place in northwestern Colombia and along the Atlantic coast and into Brazil where it nests along the northeastern coast. (Hancock, et al., 1992)

Communication and Perception

Eudocimus ruber produces a honking noise to communicate disturbances in the nest and also uses the noise in courtship. The young have a shrill cry, that they use to let parents know that they are in need of food. Touch is important during courtship. The males and females make greeting displays to one another and then wrap necks. The male produces the honking noise during courtship, while the female produces more of a squealing sound. (Hancock, et al., 1992)

Food Habits

Eudocimus ruber forages for food by either probing in water with its long bill or pecking for prey items on soil surfaces. Their main diet consists of crustaceans and aquatic invertebrates. Crayfish and small crabs compose a bulk of the diet, along with aquatic insects. Frogs, mollusks, small snakes and small fish are also prey for E. ruber. (Hancock, et al., 1992; "Scarlet Ibis", 2001)

  • Animal Foods
  • amphibians
  • reptiles
  • fish
  • insects
  • mollusks
  • aquatic crustaceans

Predation

Eudocimus ruber faces the greatest risk of predation by large cats (family Felidae) and birds of prey (order Falconiformes). Their best defense is the fact the E. ruber stays together in large groups. That way, males can use their larger size to defend their young and their female mates. The large grouping is also useful because the birds produce warning calls to warn the others of danger. (Hancock, et al., 1992; "Scarlet Ibis", 2001)

Ecosystem Roles

Eudocimus ruber lives among many other wading birds. While it can live harmoniously with other species, it also defends its individual space very aggressively. Other birds often steal the eggs of E. ruber, thus it must be protective of its territory. Because of its large colonial sizes (which can have anywhere from 20 to 600 nests, and sometimes even up to 2000 nests), E. ruber contributes significantly to the energy flow of organisms in the environment in which it lives. In one wetland, it has been noted to be responsible for 10% of the energy flow through the community.

This species forages for food with many other types of wading birds, such as storks and spoonbills and specifically has been seen living with Brazilian wading ducks. One reason that the species may be mutualistic in sharing feeding areas is that if it allows for a great number of birds to feed communally at its site, then it has a better chance to hide from predators among all the other birds. Also, many wading birds together stir up the shallow water and disturb the prey so that they are easier to find and catch. (Hancock, et al., 1992)

Mutualist Species
  • Many other types of wading birds, such as storks, spoonbills and Brazilian wading ducks.

Economic Importance for Humans: Positive

The importance of the E. ruber dates back to the 16th century when Indian tribes would use the bright feathers for adornment and also eat the meat of the bird. Eudocimus ruber meat and eggs are still used as food by humans and the feathers continue to be used as decorative objects by people both inside and outside of the Indian community. (Frederick, et al., 1990)

  • Positive Impacts
  • food
  • body parts are source of valuable material

Economic Importance for Humans: Negative

The foraging technique that E. ruber uses sends it into many different environments to find its meals. Unfortunately, their foraging can lead the birds to beaches, gardens, yards, playing fields, golf courses, and even agricultural fields where it can disrupt the residential lives and activities of people. While no major economic downfalls or disturbances have been reported as a result of E. ruber, many consider the large number of birds in these public areas to sometimes be a nuisance. (Hancock, et al., 1992)

  • Negative Impacts
  • household pest

Conservation Status

Many environmental and human threats exist for E. ruber. Overhunting, the harvesting of eggs and the selling of young as pets in open-markets are just three of the things affecting population sizes of E. ruber. Other crucial aspects threatening the species revolve around habitat loss. Nesting ground destruction and loss of foraging and feeding grounds are serious problems, along with heavy pollution in these now limited areas. Disturbance of breeding and foraging areas because of recreational activities, such as boating, is also a complication for colonies of E. ruber. There are laws and regulations that have been issued to protect E. ruber habitats and also gaurd the animal from hunting. However, in many areas, law enforcement is weak. In order to sustain the populations of E. ruber, pollution must be controlled in their breeding and feeding areas and people living in rural areas should be education about the bird. They are protected by the US Migratory Bird Treaty Act and are listed as Appendix II by CITES. (Frederick, et al., 1990)

Contributors

Alaine Camfield (editor), Animal Diversity Web.

Katherine Phelps (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

Neotropical

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

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

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.

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

diurnal
  1. active during the day, 2. lasting for one day.
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.

food

A substance that provides both nutrients and energy to a living thing.

insectivore

An animal that eats mainly insects or spiders.

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).

marsh

marshes are wetland areas often dominated by grasses and reeds.

motile

having the capacity to move from one place to another.

nomadic

generally wanders from place to place, usually within a well-defined range.

oviparous

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

polygynous

having more than one female as a mate at one time

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

social

associates with others of its species; forms social groups.

swamp

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

tactile

uses touch to communicate

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

References

Microsoft Corporation. 2001. Ibis. Microsoft Encarta Encyclopedia.

Utah's Hogle Zoo. 2001. "Scarlet Ibis" (On-line). Accessed March 29, 2004 at http://www.xmission.com/~hoglezoo/animals/view.php?id=100.

Frederick, P., L. Morales, A. Spaans, C. Luthin. 1990. The Scarlet Ibis: Status, Conservation, and Recent Research. IWRB Special Publication, No. 11.

Hancock, J., J. Kushlan, M. Kahl. 1992. Storks, Ibises and Spoonbills of the World. San Diego, CA: Harcourt Brace Jovanovich.

Hill, K. 2001. "Smithsonian Marine Station" (On-line). Accessed March 24, 2004 at http://www.sms.si.edu/IRLSpec/Eudoc_albus.htm.

Olmos, F., R. Silva. 2001. Breeding Biology and Nest Site Characterisitcs of the Scarlet Ibis in Southeastern Brazil. Waterbirds, 24(1): 58-67.

Ricklefs, R. 2000. Intrinsic aging-related mortality in birds. Journal of Avian Biology, 31: 103-111.

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