| Abstract [eng] |
This study focused on the social behavior and steroid hormones, as social behavior-affecting factors, during early ontogenesis of young grey seals (Halichoerus grypus), with a goal of contributing to a better understanding of demographic and physiological changes in this species. This work investigates the behavioral elements and factors affecting social play in grey seals. It then compares the suitability of saliva and blood based samples for steroid hormone analysis using different analysis methods and assesses their compatibility. Finally, an attempt to investigate the interactions between the behaviour of grey seal pups and steroid concentrations during the suckling and post-weaning fast periods was made. Results showed that the majority of social play interactions on land were performed by subadult males and the behavioural repertoire consisted mainly of play-fight elements. Male predominated group size, availability of haul out space and temporal proximity to the breeding season were found to have significant positive effect on the number of play interactions. Saliva required a longer collection time and resulted in lower collection success rates compared to blood samples, and is therefore recommended for trained phocids in captivity. Commercially available enzyme-linked immunosorbent assays (ELISAs) performed well for estradiol and cortisol analysis and can be used for both plasma and saliva samples, even in young grey seal pups, but saliva samples provided lower resolution for estradiol than plasma samples. Concentrations of steroid hormones in suckling grey seal pups were determined for the first time. The strongest associations were found between glucocorticoids and pup behaviour. |
