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Haematopus palliatus Temminck, 1820
American Oystercatcher
Federal Protection: No US federal protection
State Protection: Rare
Global Rank: G5
State Rank: S2
Element Locations Tracked in Biotics: Yes
SWAP 2015 Species of Greatest Conservation Need (SGCN): Yes
SWAP 2025 Species of Greatest Conservation Need (SGCN): Yes
2025 SGCN Priority Tier: High Conservation Concern
Element Occurrences (EOs) in Georgia: 36
Habitat Summary for element in Georgia: Sandy beaches; tidal flats; salt marshes, shell rakes, sand bars
This large, boldly patterned shorebird reaches 40-44 cm (16-17 in) in length. Its dark brown back contrasts with a black head and neck, red eye-ring, and yellow iris to make it distinctive from other shorebirds. The underside of the body is white, the legs are a pale flesh color, and the laterally compressed 10 cm (4 in) bill is deep orange to red with a yellowish tip. The tip of the bill is blunt and chisel-like, aiding in the opening of shellfish. Interestingly, eye color has been noted to darken with age, aiding researchers in the aging of these birds. While this species is sexually dimorphic, with females tending to be larger, there is considerable overlap in size. Adult plumage does not vary from female to male and sexes are indistinguishable in the field by sight. Bill and eye ring color become more intense prior to and through the nesting season.
None
This species exists on the highly dynamic edge of estuarine and marine coastal environments throughout its range, rarely straying any distance from saltwater. Along the U.S. Atlantic Coast the American Oystercatcher has been documented nesting on marsh islands, upland dunes, beaches, and on dredge spoils. In Georgia preferred nesting sites are areas of beach with broad sandy berms or terraced flats, off-shore sandbars, and oyster shell rakes along the intra-coastal waterway. These areas often occur at the northern or southern ends of barrier islands and at the tips of sand spits near inlets. The highest density of nesting occurs on Little Egg Island Bar and Little St. Simons Islands in the mouth of the Altamaha River, with each site hosting approximately 15 pairs annually. Oystercatchers have been documented nesting in small numbers on dredged material disposal sites in Brunswick and Kings Bay. This species nests on all of Georgia's undeveloped barrier islands except Wassaw and Sapelo, although with varying success. Foraging habitat includes shellfish beds, shoals, and intertidal sand and mud flats. After the breeding season flocks of oystercatchers can be seen along the southeast Atlantic Coast from Virginia to Georgia. In the fall and winter flocks of 50-60 birds are regularly seen on Georgia’s coast with flocks occasionally as large as 400–600 birds on the islands at the mouth of the Altamaha River.
Oystercatchers eat a wide range of marine invertebrate animals including, oysters, clams, whelks, crabs, and worms.
Oystercatchers reach reproductive maturity at 3-4 years of age. Females usually lay 1-3 eggs about 24-36 hours apart. Incubation requires 24-27 days and both sexes participate. If a clutch is destroyed, oystercatchers usually lay a replacement clutch within about 2 weeks, and can recycle like this as many as four or five times in a season if needed. Oystercatchers are solitary nesters and mated pairs aggressively defend nesting territories and adjacent foraging territories from other oystercatchers. The size of the territory varies with habitat characteristics, and on some offshore sandbars up to 5 pairs have nested in close proximity to one another with nests only 7 m (25 feet) apart. When approached by humans the non-incubating 'sentinel' bird calls, warning the incubating mate to inconspicuously leave their nest before initiating a series of loud distraction calls, often taking flight and circling the intruder repeatedly. Some oystercatchers nest among colonies of royal terns, least terns, and black skimmers in Georgia and throughout their nesting range. Breeding pairs have been observed to mate for several consecutive years, and it is possible many mate for life, though we have also documented pair affiliations changing between years, and in one case, during the same nesting season. Many local resident birds pair up as early as January, though most will not lay eggs until late March to early April. Our earliest nest in Georgia was documented on March 10th. The American oystercatcher's life span is probably 10-30 years. Notable behavioral characteristics are loud territorial displays with tail raised and neck arched, aggressive defense of nests and young often with aerial chases of much larger predatory birds, and skillful foraging techniques. Adept at locating open mussels and oysters in shallow water, this species will quickly stab the bivalve, cut the adductor muscle, and separate the top and bottom halves of the shell. It then consumes the soft contents. This all happens in a matter of seconds. The oystercatcher also uses its bill for digging and prying other clams and worms out of the sand.
Nesting oystercatchers are best surveyed from late March through June when pairs can be located most easily from boats or the air. Pedestrian surveys can also be effective on some beaches as well. A safe distance should be maintained to prevent undue stress on nesting pairs. Wintering birds can be effectively surveyed by air or boat at high tide when they are concentrated on higher portions of beach and shell bars. The DNR mid-winter shorebird survey typically does not cover the shell rakes, as it is a beach front count, and therefore misses a large proportion of the state's wintering oystercatchers.
The breeding range of the eastern race of the American oystercatcher extends along the Atlantic Coast from Massachusetts to southern Florida and along the Gulf Coast from Florida to Mexico. Permanent, year-round residents can be found in the Bahamas and islands in the Caribbean. A western population is found from Baja, California south to Argentina and Chile in South America. The highest breeding densities in the United States occur in Virginia and the Carolinas, with large postbreeding flocks gathering on the coasts of the Carolinas and Georgia in fall and winter. The area surrounding Cedar Key on the Gulf Coast of Florida is a particularly valuable wintering site for birds from U.S. Atlantic Coast breeding populations.
Shooting for the restaurant industry and egg collection in the late 1800s, habitat loss from coastal development, and disturbance of nests by humans and their pets have traditionally been the most significant threats to the American oystercatcher, rendering the species scarce in much of its range for the last century. Researchers attribute a current slow population rebound to the passage of the Migratory Bird Treaty Act of 1918, which outlawed hunting and collection of eggs. However, disturbance from beach recreation, pollution of coastal waters, and coastal development continue to threaten this bird. Recent increases in human use of coastal habitats could lead to increased disturbance of nesting and brood rearing activities that reduce reproduction and subsequently lead to population declines. Increased development pressure on beach fronts has led oystercatcher to use non-traditional habitats such as shell rakes, dredge spoil islands, and even roof-tops in several instances. Sea level rise and changes in the abundance and distribution of food resources due to climate change may also threaten this bird in the future. The biggest challenges to nesting oystercatchers in Georgia is tidal overwash of nests, and egg and chick depredation. Many predators including but not limited to crows, grackles, ghost crabs, raccoons, mink, coyotes, and great-horned owls have been documented depredating eggs, chicks, and in some cases adult oystercatchers. The recent arrival of coyotes on our barrier islands poses a serious threat to the species. A single coyote on a beach can eliminate all nest productivity, and they must be removed in order for any seabirds or shorebirds to produce young.
| Threat 1 | Threat 2 | Threat 3 | |
|---|---|---|---|
| General Threat | Invasive & other problematic species, genes & diseases | Climate change & severe weather | Human intrusions & disturbance |
| Specific Threat | Problematic native species/diseases | Habitat shifting & alteration | Recreational activities |
The lower Altamaha River delta and Little St. Simons Island currently have the highest concentration of breeding pairs (approximately 30 for both sites combined) in the state. Other important breeding areas include Cumberland and Little Tybee Islands and the shell rakes of St. Catherines and Wassaw sounds. Active management is often required to minimize local predators. Offshore bars are posted and roped to keep people and dogs off of these important nesting sites.
By the turn of the 20th century unrestricted hunting and egg collection had led to the extirpation of the oystercatcher along the Atlantic Coast north of Virginia and it was scarce throughout the remainder of its range in the U. S. Numbers increased after passage of the Migratory Bird Treaty Act (1918), and the species slowly reclaimed the northern portion of its range. Despite increases in oystercatcher numbers, estimates of the U. S. breeding population remain as low as 11,000 birds. This species was also rare in Georgia during the early 1900s and nested on Cumberland, Sea, Egg (Altamaha River), Cabbage, and Tybee Islands and Raccoon Key. Estimates of the Georgia breeding population increased from about 35 pairs at mid-century to 86 pairs in 1999, and currently is around 120 pairs. The species is currently listed as a species of extremely high priority in the Southeastern section of the U.S. Shorebird Conservation Plan because of continued loss of breeding habitat to development and apparent population declines in Virginia, North Carolina, and the Atlantic coast of Florida. While the number of nesting pairs has increased, reproductive success in Georgia is very low, with as few as 12 percent of pairs hatching eggs and 5 percent fledgling chicks in poor reproductive years. Our best year on record was 2018, when statewide productivity was 0.49 fledged chicks per pair, with a total of 61 chicks fledgling. Depredation of eggs and chicks by mammalian and avian predators, and flooding of nests during high spring tides and storms are the primary causes of reproductive failure. Coastal development and increased human use of beaches and other coastal areas is the greatest immediate threat to oystercatcher populations along the Atlantic seaboard. Growing recreational use of beaches may force nesting pairs away from beach habitat toward less productive marsh habitats. Sea level rise associated with climate change may be a significant threat in the future by reducing available nesting habitat. Current conservation measures include access restrictions on certain sand spit islands, control of invasive vegetation at some key breeding sites, and studies to determine the effects of human disturbance and contaminants on oystercatcher reproduction.
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Brown, S., C. Hickey, B. Harrington, and R. Gill, eds. 2001. The United States Shorebird Conservation Plan. 2nd ed. Manomet Center for Conservation Science, Manomet, Mass.
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Davis, M. B., T. R. Simons, M. J. Groom, J. L. Weaver, and J. R. Cordes. 2001. The breeding status of the American Oystercatcher on the east coast of North America and breeding success in North Carolina. Waterbirds 24:195–202.
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George, R. C. 2002. Reproductive ecology of the American Oystercatcher (Haematopus palliatus) in Georgia. Master’s thesis, University of Georgia, Athens.
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Rappole, J. H. 1981. Management possibilities for beach-nesting shorebirds in Georgia. Pp. 114 – 126 in R. R. Odom and J. W. Guthrie, eds., Proceedings of the Nongame and Endangered Wildlife Symposium. Technical Bulletin WL5. Georgia Department of Natural Resources, Game and Fish Division.
Brown, S. C., S. Schulte, B. Harrington, B. Winn, J. Bart, and M. Howe. 2005. Population size and winter distribution of eastern American Oystercatchers. Journal of Wildlife Management 69: 1538-1545.
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Michael J. Harris, R. Clay George, Todd M. Schneider, Bradford Winn, and Timothy S. Keyes
M. Harris, 1999: original account
C. George, 2010: Breeding Bird Atlas species account
T. Schneider and B. Winn, July 2010: modified and edited text
K. Owers, July 2010: updated status and ranks, added pictures
G. Krakow, April 2016: deleted dead URL under Hunter, W. C
T. Keyes, updated/edited Jan 2019
T. Schneider, May 2019: added photo 4
