Haematopus palliatusAmerican oystercatcher

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Geographic Range

American oystercatchers (Haematopus palliates) have a far spreading range across the world, they have been found in the United States, Cuba, Brazil, and Mexico. Among the several other oystercatcher species, American oystercatchers are the only species native to the Atlantic Coast of North America. Along the Atlantic Coast, their breeding range spans between Massachusetts and Florida. American oystercatchers can be found year-round throughout parts of the Caribbean and the Gulf Coast. In South America, this species occurs as far south as Chile and Argentina; they are also found locally on both coasts of Mexico and Central America, breeding as far north as Baja, California. There is still relatively little known about the routes these birds take when traveling from wintering grounds to breeding spots. (Elphick, et al., 2001; George, 2008; Nol and Humphrey, 1994)

Habitat

American oystercatchers are commonly found on mudflats, sandy beaches, and occasionally on rocky shores. Nesting habitats include upland dunes, marsh islands, beaches, and dredge spoil islands. Nesting may occur more often in salt marshes along the northern end of their range to escape possible disturbances brought on by humans. During the winter months, American oystercatchers tend to be concentrated in areas with abundant food sources such as reefs, oyster beds, or clam flats. During spring and fall migration, these birds can be found in shellfish beds, sand flats, or intertidal mudflats. They rarely venture inland, typically roosting on adjacent dunes, marsh islands, or beaches. Their nest sites generally range from 1 to 2 m above sea level. Higher elevation nests are less likely to be damaged by tidal flooding, but are more vulnerable to mammalian predators such as skunks and minks. (Elphick, et al., 2001; Nol and Humphrey, 1994; Stokes and Stokes, 2013)

Physical Description

American oystercatchers are relatively large and conspicuous shorebirds. They are 40 to 44 cm long, have an average wingspan of 81 cm, and weigh between 400 and 700 g. Although males and females are similar in appearance, females tend to be larger. American oystercatchers are dark brown on the mantle and wings, with black heads and necks. Bright white undersides contrast greatly with these dark upperparts. The narrow white wing patch and white "V" on their upper rump both become visible in flight. Their long, straight, chisel-like bill is red to orange in color, with dark colorings visible toward the end in juveniles. Their legs are long, pale pink, and lack a hallux. Their iris is bright yellow with a visible red orbital eye ring. Their black head and neck, brown mantle, red eye ring, and yellow eyes distinguish this bird from other similar species. (Elphick, et al., 2001; Nol and Humphrey, 1994; Stokes and Stokes, 2013)

  • Sexual Dimorphism
  • female larger
  • Range mass
    400 to 700 g
    14.10 to 24.67 oz
  • Range length
    40 to 44 cm
    15.75 to 17.32 in
  • Average wingspan
    81 cm
    31.89 in

Reproduction

Though American oystercatchers are typically monogamous, cases of polygamy have been documented in this species. Pair bonding occurs in the spring when both sexes arrive at the breeding grounds. While most birds choose a new mate each year, some individuals remain with their partner throughout their lives. American oystercatchers attract their mates by performing courtship displays that include both visual and auditory aspects. Courting birds walk parallel to one another while holding their necks outstretched, looking downwards, and making a loud piping call. Next, they bob their heads up and down and run side by side while changing the pitch and intensity of their call. Copulations are typically initiated by the female, who stiffens her body, raises her tail, straightens her legs, bends forwards, and draws in her neck. The male responds to this change in posture by mounting the female for 1 to 2 seconds. (George, 2008; Nol and Humphrey, 1994)

American oystercatchers usually breed between February and July and raise one brood per summer. Both parents are involved in nest building, brooding, incubation, and nest defense. Adults nest in shallow scrapes along the ground, which they excavate with their feet. American oystercatchers often make several scrapes before selecting one to use. Previous nest scrapes are sometimes reused. Most nests are located on salt marshes, rocky shores, or beaches. They are occasionally lined with plant matter and pebbles to camouflage them from predators. Chicks are precocial and leave the nest within 24 hours of hatching. Both parents feed the chicks until they fledge; some juveniles remain with their parents for up to 6 months. Juveniles become sexually mature in 3 to 4 years. (Elphick, et al., 2001; Lauro and Burger, 1989; Nol and Humphrey, 1994)

  • Breeding interval
    American oystercatchers produce one clutch per year.
  • Breeding season
    These birds breed from February through July.
  • Range eggs per season
    1 to 6
  • Range time to hatching
    24 to 28 days
  • Average fledging age
    35 days
  • Range time to independence
    2 to 6 months
  • Average age at sexual or reproductive maturity (female)
    3-4 years
  • Average age at sexual or reproductive maturity (male)
    3-4 years

Both sexes invest substantial time and energy to raise their chicks. Males and females both engage in nest scraping several weeks before egg laying occurs, though males may perform this activity more often. While both parents incubate the eggs and feed the nestlings, females tend to spend more time brooding and males tend to do more of the feeding. Chicks rely on their parents for food until their bills become strong enough to probe and stab, a process that takes approximately 60 days. During this time, adults retrieve soft parts of marine invertebrates and either carry them back or eat and regurgitate them for their young. In documented cases of cooperative or communal breeding, parental duties are shared by non-parental individuals. Cooperative breeding may primarily occur in areas with high nesting densities. (George, 2008; Lauro and Burger, 1989; Nol and Humphrey, 1994; Nol, 1985)

  • Parental Investment
  • precocial
  • male parental care
  • female parental care
  • pre-fertilization
    • provisioning
    • protecting
      • male
      • female
  • pre-hatching/birth
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • extended period of juvenile learning

Lifespan/Longevity

Many birds belonging to order Charadriiformes are long lived, including American oystercatchers. Re-sightings of previously banded individuals confirm that these birds frequently reach ages of 10 years and older. The oldest documented American oystercatcher was 17 years old. Some individuals may even survive up to 20 to 40 years, like their close relatives, European oystercatchers. (Nol and Humphrey, 1994)

  • Range lifespan
    Status: wild
    17 (high) years

Behavior

American oystercatchers are migratory and diurnal birds, which make loud, recognizable "wheep" or "wee-ah" calls. They are a social species and tend to roost communally in groups containing up to 100 or more individuals. During the day, these birds can be seen running or walking more often than flying. Their normal flight pattern of rapid and deep wing beats becomes softer during courtship displays and when predators are nearby. Much of their daily routine is spent preening, head scratching, sleeping, standing, and sunbathing. Their feeding behavior sets them apart from many other shorebirds. (George, 2008; Nol and Humphrey, 1994; Stokes and Stokes, 2013)

Home Range

There is little available information on the home range size of American oystercatchers.

Communication and Perception

American oystercatchers are very vocal, especially during the breeding season, when their breeding display is spectacularly auditory and visual. Their call is loud, rising, and then descending. It is used for a variety of purposes including: greetings between individuals, warning alarms, territorial disputes, establishing dominance in feeding areas, and begging for food from parents. (Nol and Humphrey, 1994; Stokes and Stokes, 2013)

Food Habits

American oystercatchers feed mainly on marine invertebrates, bivalves, mollusks, worms, clams, crabs and shell fish. They also eat small fish on occasion. Foraging occurs primarily in intertidal areas with a rich diversity of marine invertebrate species. Their long, brightly colored bills help them prey on bivalves and probe for marine invertebrates. These birds utilize two distinct feeding techniques, both of which are successful. The first technique is called "stabbing", where a bird walks around an exposed shellfish bed until it spots an open bivalve, which it quickly stabs. After a few quick thrusts from a chisel-like bill, the adducator chain breaks, and the bird can consume the soft parts. This technique is not without risk, as deeply rooted bivalves can clamp down on their bill and hold it down until it drowns in the rising tide. The second feeding technique is called "hammering", in which the bird simply plucks a single mussel from a group of mussels, takes it to a different location, and holds it in its beak in such a way that when it begins hammering, the shell breaks easily and the chain that holds the bivalves together is severed. Their major food items include soft-shell clams, blue mussels, sandworms, razor clams, oysters, and mole crabs. (George, 2008; Nol and Humphrey, 1994; Stokes and Stokes, 2013)

  • Primary Diet
  • carnivore
    • eats non-insect arthropods
    • molluscivore
    • vermivore
    • eats other marine invertebrates
  • Animal Foods
  • fish
  • mollusks
  • terrestrial worms
  • aquatic or marine worms
  • aquatic crustaceans
  • other marine invertebrates

Predation

While skunks, raccoons, great black-backed gulls, and herring gulls all prey on American oystercatcher eggs, large raptors are the primary predators of adult birds. Some American oystercatchers are also preyed on by black-crowned night herons and American crows. However, human disturbance, domestic cats, and domestic dogs likely pose the biggest threat to American oystercatchers. (George, 2008; Nol and Humphrey, 1994)

Ecosystem Roles

There are records of American oystercatchers and closely-related Eurasian oystercatchers engaging in kleptoparasitism. Common gulls use American oystercatchers as hosts to access food. (Martinez and Bachmann, 1997; Nol and Humphrey, 1994)

Economic Importance for Humans: Positive

American oystercatchers are an indicator species whose presence in certain areas can help humans infer the environmental conditions of those sites. (Nol and Humphrey, 1994; Nol, 1985)

  • Positive Impacts
  • food
  • body parts are source of valuable material
  • research and education

Economic Importance for Humans: Negative

There are no known adverse effects of American oystercatchers on humans.

Conservation Status

American oystercatchers are listed as a species of least concern in many coastal states. However, because they are rather shy birds, they do not do well with human interaction. They are losing habitat to human disturbance and development along beaches, and to other birds. American oystercatchers tend to avoid nesting near gulls where their nests would be vulnerable to attacks. Market hunting and egg collecting in the 19th Century can also help explain the low population numbers in North America. (George, 2008; Nol and Humphrey, 1994)

Contributors

Maddie Hardin (author), University of Wisconsin - Stevens Point, Christopher Yahnke (editor), University of Wisconsin-Stevens Point, Leila Siciliano Martina (editor), Animal Diversity Web Staff.

Glossary

Atlantic Ocean

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

World Map

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

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map

acoustic

uses sound to communicate

aposematic

having coloration that serves a protective function for the animal, usually used to refer to animals with colors that warn predators of their toxicity. For example: animals with bright red or yellow coloration are often toxic or distasteful.

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.

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.

cooperative breeder

helpers provide assistance in raising young that are not their own

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

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

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.

female parental care

parental care is carried out by females

food

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

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

molluscivore

eats mollusks, members of Phylum Mollusca

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.

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

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

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).

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

Elphick, C., J. Dunning Jr., D. Sibley. 2001. The Sibley Guide to Bird Life and Behavior. New York: Alfred A. Knopf.

George, R. 2008. "Reproductive Ecology of the American Oystercatcher (Haematopus palliatus) in Georgia" (On-line pdf). Accessed August 10, 2013 at http://athenaeum.libs.uga.edu/bitstream/handle/10724/5995/george_russell_c_200208_ms.pdf?sequence=1.

Lauro, B., J. Burger. 1989. Nest-site selection of American Oystercatcher (Haematopus palliatus) in Salt Marshes. The Auk, 106: 185-192.

Martinez, M., S. Bachmann. 1997. Kleptoparasitism of the American Oystercatcher. Marine Ornithology, 25: 68-69.

Nol, E. 1985. Sex Roles in the American Oystercatcher. Behaviour, 95: 232-260.

Nol, E., R. Humphrey. 1994. American Oystercatcher (Haematopus palliatus). The Birds of North America, No. 82: 1-23.

Stokes, D., L. Stokes. 2013. The New Stokes Field Guide to Birds Eastern Region. New York, Boston, London: Little, Brown and Company.