The birds often use ditracting displays, pretending to have a broken wing or surprising other birds that invade their nests, but are otherwise non-territorial. Both parents incubate two or three eggs on average, and mates may stay together for several years. Locally, since there are no oysters, the bird is not so aptly named, but it does prey upon a variety of intertidal shellfish, including limpets, chitons and various snails. Birds of the same family occupying the same ecological niche are found throughout the shorelines of the world.
Their long, chisel-like beak is perfect for prying the shells open to feed on the soft flesh inside. The skull to the left was the product of predation by a river otter in 2001. The presence of the black oyster catcher nesting areas can be noted upon the discovery of piles of empty shells in the nooks and crannies of Race Rocks. Analysis of the different shells found in these piles has been done and it serves as an indicator of shellfish species diversity on the island, as well as the food web of the oystercatchers. See the results of the Fall 1999 collection of shells from the midden of the oystercatchers. Also go to the Lab on the Ecological Niche of the Black Oyster-catcher.

	The Pacific Wildlife Foundation has provided a useful reference at this link.
see this Video by Paul Omole of a Black Oystercatcher Feeding.