Found singly, in pairs or in small flocks (4) (5) (8), the sooty oystercatcher is generally considered to be a non-migratory species, although in some parts of its range it may move short distances to breed on rocky islands (2) (3).
The sooty oystercatcher eats a wide variety of invertebrate prey (8), including limpets, whelks, crustaceans, oysters, periwinkles and mussels, and it also occasionally eats dead fish (2) (7) (10). All oystercatcher species use a variety of techniques to attack their prey, including prising, probing, stabbing and hammering (2), and by employing these methods the sooty oystercatcher is able to defeat its heavily armoured prey, even tackling sea urchins (4).
The sooty oystercatcher breeds during spring and summer (4), from August to January (2), and is a monogamous species (11). A sooty oystercatcher clutch consists of between two and four eggs (2), although two is most common (2) (3). The eggs are a light stone colour, marked all over with dark brown or purplish blotches (3), and are laid in a shallow scrape in the ground (2) (4). The scrape is often located among boulders, and may be lined with shell fragments. The egg incubation and fledging periods of the sooty oystercatcher are unknown (2).