The Early Ethology of Wild Grey Seal (Halichoerus grypus) Neonates over the Period of Maternal Dependency:
An Assessment of the Nature and Function of Behaviour

Abstract

With the purpose of quantifying the behavioural patterns of pre-weaned grey seal (Halichoerus grypus) neonates, detailed neonatal behavioural records were used to provide an overview of typical behaviour budgets during the brief period of maternal dependency, or lactation period. Neonates were shown to spend the majority of their time inactive, with the assumption that such immobility maximises energy retention and mass gain during the short nursing period. Investigation at an individual-level revealed that neonates show consistent differences in the expression of some behavioural traits relative to one another over time. However, behavioural repeatability estimates for neonates were found to be lower than those so far reported in adult behavioural traits, suggesting that individual behavioural consistency may increase with age in this species. To current knowledge, this study represents the first attempt to quantify individual behavioural consistency in the neonatal age-class in this species.
This study provides a rare exploration of neonatal play behaviour in grey seals. There is weak suggestion that different types of play show different developmental trajectories over time, inferring that play function(s) could be dynamic. However, this area of study requires further systematic research to confirm these ideas. Maternal nutritional investment was not found to have a direct relationship with neonatal play. Interestingly, when the independent play behaviour of male and female siblings was compared in order to control for maternal and genetic differences, a sex difference was indicated in relation to maternal condition. Sons of poorer condition mothers (estimated by post-partum mass) were found to play more, whilst daughters of better condition mothers played more by contrast. An intriguing relationship was also indicated to suggest that the offspring of mothers in poorer condition (based on morphometric estimations) engage in more social play, predominantly with the maternal figure. Validation of estimations of maternal body condition is essential for enhancing confidence in these initial results. Increasing sample size in complementary future research would also be highly advantageous.