Australian Sea Lion (Neophoca cinerea)
The Australian Sea Lion (Neophoca cinerea) is endemic to Australia, found distributed throughout tens of islands and mainland sites in the south and west of the country. ‘Cinerea’ in their latin name may be a reference to their grey colouration. Due to historic hunting, fishery bycatch, and now genetic isolation amongst populations, the IUCN list the species as Endangered. Estimated population size = 12,690.
N. cinerea are large, sexually dimorphic eared seals (males ♂ up to 2.5 m long/ 300 kg, females ♀ up to 1.8 m/ 110 kg). With bulky bodies and comparatively short flippers, both sexes have somewhat squat heads with elongated muzzles and long, white vibrissae. The males have huge necks with manes on top. Colouration is quite varied and distinctive too, with the males generally rich dark brown to black, while the females range from silvery grey through to yellowish buff. The female sea lions are markedly different shades on their dorsal and undersides, with underbody and face paler than on top. They tend to have whitish eye rings and very pale snouts compared with the rest of the face. Males have striking blond yellowish fur on the crowns of their heads and growing down the back of their mane, accentuating their dark faces.
The diet of N. cinerea seems to comprise heavily of cephalopods (octopus, squid and cuttlefish), fish (filefish, wrasse, perch, cod, mullet, redfish, whiting, guitarfish and stingray), and crustaceans (crab, prawn and lobster). It is likely due to the variation in different individuals that they are fairly opportunistic feeders, taking advantage of availability. N. cinerea are not known to dive that deeply, and tend to forage along the benthos at less than 100 metres. Trips to sea are made during the day and are comparatively short compared with other otariids.
Sexual maturity – males ♂ 6-8 years old/ females ♀ 4-6 years old.
N. cinerea has an unusual breeding cycle which is somewhat different from that of other pinnipeds. Instead of having fixed seasons, the species may breed at any time of year. Different populations are asynchronous from each other. The breeding season may then last for a non-fixed length of time (anything from 4 to 9 months), and it will be on average 18 months before another breeding season occurs. The species is polygynous like other otariids, but the males do not form fixed territories. Instead they will ‘guard’ one female until she comes into oestrus, then return to sea to forage. On their return they will choose another female and repeat the process. Gestation has around a 4 month delayed implantation period, and will then take 14 months to reach full term. Pups are born with a dark, chocolatey-brown coat that often lightens over time, before moulting into the adult coat at around 4 months. The mother remains with her pup for 10 days solid before resuming short foraging trips. Suckling continues for the 15-18 months before the next breeding season, and in the case that the female does not birth again the next year, she may continue nursing her original pup for as long as 2 years or more. Pups learn to swim quickly, and are soon confident in accompanying their mother to forage. Moult in N. cinerea is postnatal, but can occur throughout the year, generally lasting 3-5 months. The life expectancy of this species is around 25-26, with males often falling a little short of this.
N. cinerea do not have officially recognised subspecies, however, there is substantial genetic separation between different breeding colonies, which means that in some respects, these different populations warrant being considered as such.
Photos: Bekka Hall, NSW, Australia (top) and Katharina Peters