Anomalous lanugo coat colourations in sub-Antarctic fur seal ( Arctocephalus tropicalis ) pups born on Marion Island

Anomalous pelage colourations are not uncommon amongst pinnipeds but have not been documented in sub-Antarctic fur seals ( Arctocephalus tropicalis ). Fur seals ( Arctocephalus spp.) have been monitored on Marion Island since 1973, and as part of the long-term monitoring programme, any atypical sightings of fur seals were recorded. Fourteen sub-Antarctic fur seal pups with anomalous lanugo coat colourations were observed on Marion Island between 2008 and 2018. Most of these pups were born to typically coloured sub-Antarctic fur seal mothers. The observed coat colourations are an anomaly of their natal (lanugo) black coats. While all pups had normal colour vibrissae and eyes, they had creamy muzzles and brown-to-blonde ventral and belly colouration. The fur on the flippers was a light tan to cream in colouration, darkening towards the border of the flipper. The dorsal side of the pups all appeared to be light grey in colour. All pups appeared to be healthy. Once moulted, these pups had normal adult pelage colourations. The frequency of occurrence of these anomalous lanugo coat colourations was low, suggesting that this is a particularly rare phenomenon. The causes for these anomalous coat colourations are unknown. These observations are the first records of sub-Antarctic fur seal pups with anomalous lanugo fur colourations from the Prince Edward Islands and represents the first of such observations in sub-Antarctic fur seals worldwide. It also represents the first report on anomalous colourations of pinnipeds that appears to exclusively influence the lanugo fur.