Movement patterns and activity levels are shaped by the neonatal environment in Antarctic fur seal pups

Tracking studies of juveniles are rare compared to those of adults and consequently, little is known about the influence of intrinsic and extrinsic factors on activity during this critical life stage. We therefore collected GPS data from birth until moult from 66 Antarctic fur seal pups in two nearby but contrasting breeding colonies. The Special Study Beach (SSB) is a high-density colony separated from the inland tussock grass habitat by a steep gully, whereas Freshwater Beach (FWB) is a low-density colony that is topographically more open. We investigated the explanatory power of multiple individual-based and environmental variables using a hidden Markov model. We found that activity was typified by central place exploration, with directed movement away from and subsequent return to a location of low activity. The probability of such directed exploration was unaffected by several factors known to influence marine mammal movement including sex, body condition and temperature. Conversely, FWB pups were more active, increased their activity with age and transitioned earlier into the tussock grass, which offers protection from predators and extreme weather. Our study illustrates the profound importance of extrinsic factors to early movement and highlights the adaptive potential of movement in the face of environmental variability.