The snowy sheathbill is an opportunistic scavenger that will eat almost anything that it can find or steal. During the winter time, it will scavenge around scrap heaps, or amongst seaweed for a variety of invertebrates, but during summer when seals are breeding, it will gorge upon seal stillbirths, or probe at seal wounds and pick at the flesh or take some blood (4). It will also eat the placenta of birthing seals and even try to consume the umbilical cord of newborns while it is still attached (3). The snowy sheathbill is a messy eater, even known to consume the faeces of seals, and, consequently, it spends a large proportion of its time preening and cleaning its feathers (4). During its own breeding season, the snowy sheathbill takes up and vigorously defends territories, comprising a number of penguin pairs. It will harass the penguins to try and make them regurgitate their krill catch, or steal their eggs and young chicks.
The snowy sheathbill arrives at breeding areas in October and November, and lays usually two or three creamy coloured, pear-shaped eggs between December and January at intervals of four days (2) (3). The cup-shaped nest is lined with a combination of bones, guano, dead chicks and even rubbish, and the eggs are incubated for 28 to 32 days (2). Once fledged, the young birds begin to forage along the shoreline for scraps of fish, limpets and kelp before leaving the breeding site between April and June to migrate to more northern latitudes (2) (4). The snowy sheathbill is monogamous, with a high degree of fidelity for its breeding site, meaning that more often than not, it will return to the same site each year to breed (2) (3).