Unlike many other Antarctic seal species, the Ross seal is largely solitary and does not congregate in large colonies to breed. Instead, single females haul out onto the ice between November and December to give birth to the single pup that was conceived the previous season, with pupping peaking between 3rdand 18th December. The pup is nursed on the mother’s energy-rich milk and is capable of swimming very soon after birth (3). The females mate again in late December, probably in the water, but implantation of the fertilised egg is delayed for two to three months, allowing the female to moult, feed and gain valuable weight before the foetus develops (2) (3). The young pup weans after around a month, and most females will mate at three years of age, while males mature at two to three years. The Ross seal has a life expectancy of up to 21 years (2).
On land this seal has no predators, but in the water it may fall prey to orcas (Orcinus orca) or leopard seals (Hydrunga leptonyx). The Ross seal itself preys largely on cephalopods, although it may also sometimes feed upon fish and krill, and this specialised diet allows this seal to avoid competition with other marine mammals. Its prey is captured at depths of between 100 and 200 metres after a prolonged dive, which lasts for around six minutes (3).
This seal displays a variety of vocalisations which may be used for communication between seals or to warn off predators. When approached by people on land, it may open its mouth widely and emit a series of trills and thumping noises. This warning call is often accompanied by an aggressive posture, with the teeth displayed and the chest thrusted outwards, making the seal appear larger in size. In the water this seal makes a variety of chirps, and it had been suggested that these may be used to defend territories from other Ross seals, although the solitary nature of this species suggests that this is unlikely (2). Explosive noises, pulsed chugs and siren calls are also used by the Ross seal, some of which are used during mating and in communication between the mother and pup (3).