Conservation and Management

Initial declines in numbers perhaps owing to egg-collecting, for food (Richards 1888). Oystercatchers are large, flamboyant shorebirds and probably also made an easy target for market gunners (Forbush 1912, Bailey 1913, Bent 1929), although historically they were considered rare in the bag of coastal gunners and their flesh “ill-flavoured” (Giraud 1844, Samuels 1870, Brewster 1885, Forbush 1912, Bailey 1955). Human populations on the Atlantic coast also continued to increase during this period; oystercatchers are shy and intolerant of human disturbance (Bent 1929, Barbour 1943, Finch 1972).

With the passage of the Migratory Bird Treaty Act in 1918, the direct human impact on the American Oystercatcher was significantly reduced. Populations started to rebound slowly and a gradual “re-expansion” of the breeding range northward began (see Distribution: historical changes). Current populations stable or expanding throughout the center of the species’s range. Significant threats to the future success of this species are human use and development of coastal areas (Bent 1929, Tomkins 1954, RCH, Kale et al. in prep.). Some expansion may occur whenever dredge spoil becomes available for nesting (Lauro and Burger 1989), as the species adapts well to such changes in its environment. Populations in Baja, on the east coast of Mexico, and in Florida and the West Indies will probably remain small; species limited primarily to small offshore islands (see Distribution: historical changes).

The distribution and breeding success of oystercatchers may be limited by interspecific competition (particularly with Herring Gulls) at some sites (RCH), although in Virginia and Long Island (NY) they nest near gull and tern colonies without any apparent negative effects (EN, B. Lauro pers. comm.). Oystercatchers are generally shy and intolerant of larger colonial nesting seabirds; historically, much of their preferred nesting habitat has been occupied by seabird colonies (Bent 1929, Sprunt and Chamberlain 1949, Tomkins 1954, Post and Raynor 1964, RCH).

Species afforded different status throughout its range, so conservation efforts tend to be implemented on a local or intra-state basis. Efforts need to focus on protecting breeding and feeding habitat and, in some cases, on predator control. Nesting areas are best protected by excluding humans. In areas where high tides consistently result in nest loss, artificial nest platforms may be a potential management tool. Two such platforms (constructed of three automobile tires tied together and filled with oyster shells) were placed on territories in coastal Virginia, where nests had been washed away by high tides for 5 consecutive years. The platforms were used consistently (and often successfuly) for nesting from 1983 to 1992 (EN).

Protection of feeding habitat requires maintaining overall health of the environment; oystercatchers feed primarily on shellfish and marine invertebrates. Large-scale measures taken to prevent or restrict pollution of shellfish beds for commercial interests also benefit the birds.

Throughout its range, this species tends to be more common and more successful in areas with few or no terrestrial predators (e.g., islands). Efforts to remove domestic and feral predators from breeding sites, especially islands, are helpful. Removal of avian predators may also be required in some instances; e.g., Herring and Greater Black-backed gulls not only eat oystercatcher eggs and chicks, but may compete with this oystercatcher for nesting habitat, particularly in the northern end of its present range (RCH). Predation by other avian predators such as crows and Black-crowned Night-Herons (Nycticorax nycticorax) is normally light, within natural mortality rates.

We recommend designating the species one of Special Concern in the New England states and in Delaware. It is already of Special Concern in Florida and becoming increasingly rare in Mexico (but with no official designation). Periodic census and/or inventory of populations is also necessary to document the current status of this species throughout its range.