The pied oystercatcher is usually found in pairs (3) (10) or in small groups (2) (3) (4), and is known to associate with sooty oystercatchers (Haematopus fuliginosus) and other shorebirds such as curlews, stints and sandpipers (4). However, during the breeding season the pied oystercatcher pairs spread themselves evenly along the beach, and are less sociable (3).
Invertebrate prey such as bivalves, worms, crustaceans and insects form the bulk of the pied oystercatcher’s diet (2) (9) (10) (11), although it also eats fish and fish eggs (2) (11). This species often feeds on large cockles, which it pulls out of the sandy substrate and hammers open to get to the fleshy parts (3), and it also uses its long, knife-like bill to pry open oysters and other shellfish (5).
The pied oystercatcher is a monogamous species (2) (11). The timing of breeding varies depending on the location, occurring between May and September in the northern parts of its range, and between August and January in the south (2). The pied oystercatcher does not make a nest (5), instead laying its eggs in a shallow scrape in the sand, usually just above the high-tide mark (2) (3). It is also known to leave the shore and move to small islands and rocky promontories to breed (4).
Pied oystercatcher clutches usually contain two eggs (2), which are a buffy stone colour, and are marked with large irregular blotches of dark chestnut-brown (4). The eggs are incubated for 28 to 32 days, before the downy, grey-brown speckled chicks hatch (2). The young pied oystercatchers are soon capable of running (4), but are not capable of flight until they are between 42 and 49 days of age. The young birds remain in the adult territory for one to six months, and will not breed until they are between four and six years old (2).