Nature’s Notebook
The American Oystercatcher
The American oystercatcher ( Haematopus palliatus) is a shorebird species that occurs only in the coastal zone for the eastern and gulf coasts of the United States. It is the largest and heaviest shorebird that occupies salt marshes and coastal islands throughout the year along the southeastern United States coasts. A recent survey by the Florida Fish and Wildlife Conservation Commission (FWC) estimates the number of American oystercatchers during the breeding season (March through August) in Florida to be around 1,000 individuals. This is not a favorable population estimate.
Feeding and breeding habitats include oyster bars, dunes, shell rakes, barrier beaches, mudflats, sandbars and salt marsh islands. The oystercatcher is also using nontraditional habitats for nesting such as dredge spoil islands and rooftops in Florida (S. Schulte, S. Brown, D. Reynolds, and the American Oystercatcher Working Group. 2007. Version 2.0. American Oystercatcher Conservation Action Plan for the United States Atlantic and Gulf Coasts). Like many other shorebirds, the oystercatcher needs extensive mudflats and sandbars for feeding, resting and nesting. It also needs these areas and shell-covered beaches to be undisturbed by humans and predators during nesting. It lays two to four eggs in shallow scrapes it makes in the sand. The eggs incubate for 24 to 27 days, and hatchlings fly 34 to 37 days after hatching. The young remain dependent on their parents for feeding for a minimum of one month after flight.
Unfortunately, the traditional nesting habitats of the oystercatcher are very popular with humans, and its nests are easily disturbed. Trash left by humans also attracts egg and chick robbers such as raccoon ( Procyon lotor), coyote ( Canis latrans), gray fox ( Urocyon cinereoargenteus), dog ( Canis familiaris), feral cat ( Felis cotus), herring gull ( Larus argentatus), laughing gull ( Larus atricilla) and fish crow ( Corvus ossifragus). Since the oystercatcher is very sensitive to human disturbance and mammal and bird
THE OYSTERCATCHER, LIKE MANY OTHER SHOREBIRDS, NEEDS EXTENSIVE MUDFLATS AND SANDBARS FOR FEEDING, RESTING AND NESTING. IT ALSO NEEDS THESE AREAS AND SHELL-COVERED BEACHES TO BE UNDISTURBED BY HUMANS AND PREDATORS DURING NESTING.
predators, its safe nesting habitats are declining. It is therefore considered a Species of Special Concern in Florida by FWC.
The American oystercatcher measures 47 cm/18.5 in and weighs 650 g. It is a striking dark black-brown and white bird with pink legs and bright red-orange bill. Females and males are similar in appearance. Breeding plumage is virtually identical to nonbreeding plumage. The oystercatcher uses its powerful laterally compressed bill to open mollusk shells and sort through heavy shell substrates in search of bivalves and other invertebrates. This bird also probes sandy and muddy areas for sandworms and soft-shell clams.
The American oystercatcher is a fairly common permanent resident of beaches along both peninsular coasts. The highest number of wintering oystercatchers in Florida occurs on the gulf coast from the Ten Thousand Islands of the Everglades to Apalachicola Bay in the panhandle (Schulte et al. 2007). Flocks of the American oystercatcher can be observed on the beaches at and near Sanibel Island, but its population is most concentrated near Cape Romano, Cedar Key and Tampa Bay. The islands of the Lower Suwannee River and Cedar Key have the highest density of wintering oystercatchers in Florida. The dredge spoil islands and protected beaches at Tampa Bay are among the oystercatcher’s most important nesting areas. This location has one-third of the known nesting population of oystercatchers in Florida. The low number of nesting sites and its use of roofs of coastal buildings and dredge spoil islands for nesting indicate that not enough is being done to protect American oystercatcher beach nest sites.
Florida’s beautiful beaches and rich bird life are big attractions to vacationers, but this also contributes to the major threats to the American oystercatcher—human disturbance, nest predation and habitat loss from development. Negative impacts to the oystercatcher population will become more pronounced as the human population in coastal areas increases and more people visit beaches and waterways for recreation.
While most residents and visitors avoid disturbing areas that are posted with “No trespassing” signs, some people are not aware of the impacts they may cause by disturbing nesting and roosting sites. Recreational activities on oystercatcher-protected beaches, barrier islands and other nesting and wintering sites can cause nest failures or even complete avoidance of suitable habitat. In addition, increased nest predation by raccoons, dogs, cats, crows and gulls is associated with trash and food left by humans at or near nesting sites. By simply staying out of these protected areas, humans can have a positive impact in protecting the American oystercatcher population.