Female grey seals allocated more resources to individual sons than to individual daughters. Mothers of male pups spent significantly larger proportions of their time defending and feeding their young than did mothers of female pups. The amount of time females spent ashore and the proportion of time spent in various behavioural states was influenced by the habitat of the birth site and the age of the pup.

Grey seal neonates spent the majority of their time prone and immobile, perhaps to allow maximum energy retention (maximum mass gain) and to facilitate mothers relocating their pups. The proportion of time pups spent in the various behavioural states was influenced by the whelping habitat. Pups became increasingly active with age. Males were significantly more aggressive than females and, at one site they performed nosing behaviour with their mothers significantly more often than did female neonates.