Investigating the links between behavioural types and mate choice in a polygynous pinniped

Abstract

Consistent individual differences in behaviour (CIDs) or behavioural types have now been shown in a broad range of taxa, from Cnidarians to birds and mammals. An individual’s behavioural type can influence may aspects of its life history including foraging strategies and mate choice decisions. Grey seals (Halichoerus grypus) have been shown to exhibit behavioural types ranging from proactive to reactive but the implications of this on sexual behaviour and mate choice decisions have not yet been investigated. This study tests the prediction that females with a more reactive personality type should be more choosy in their mate choice decisions.
Behavioural observations were made at two distinct sites within Donna Nook breeding colony on the Lincolnshire coast, UK. The RAF site was characterised by flat topography and very low human presence while the public site was more topographically varied and had a high level of human presence. The behavioural types of females were determined by examining the rate at which they performed pup-checking behaviour in both disturbed and undisturbed situations. Females were considered to have a more proactive behavioural type if they maintained a relatively constant rate of pup-checking across situations and a more reactive behavioural type if their rate of pup-checking changed across situations. Owing to their tendency to be found on the edges of the colony where they are subject to increased harassment by transient males it was predicted that females with a more reactive behavioural type would show frequent and intense aggression towards males. In contrast, due their tendency to occupy the best pupping sites at the centre of the colony which are occupied by more dominant males it was predicted that females with a more proactive behavioural type would show fewer and less intense aggressive interactions towards males. This pattern would indicate female mate choice by showing that females respond more aggressively to low ranking transient males than they do to more dominant males suggesting a preference for the latter. Detailed accounts of all aggressive interactions involving focal females were recorded ad-lib in the field.
In agreement with previous studies, evidence of CIDs in the pup-check rates of females in undisturbed situations was identified at this colony. However, in contrast with past research no evidence of CIDs in disturbed situations was found. A significant difference was found in the mean pup-check rates of females at the two study sites with females at the less disturbed RAF site pup-checking at a significantly greater rate. The data also showed significant differences in rates and intensities of aggression between the two study sites with females at the RAF site showing a higher rate but lower intensity of aggression than those at the public site. However, no evidence was found to support the hypothesis that reactive females show higher level of aggression towards males than do proactive females. Thus, no evidence of female mate choice in grey seals was found in this study. Despite this, potentially interesting effects of topography and/or anthropogenic presence on grey seal behaviour were found and these may prove to be interesting avenues for future research.