Moulting phenology of the harbour seal in south-west Ireland

Abstract

Studies on the phenology of harbour seal moult have been carried out in the Atlantic and Pacific, however there has been no research into this process in the Republic of Ireland, at the southern edge of the species range in the north-east Atlantic. Population estimates of harbour seals are derived by counts primarily during the moulting seasons. In the absence of information on the moult phenology planning the optimal timing of such surveys is impossible. Furthermore, changes in moult phenology may reflect changes in resource availability or competition, or demographic changes. The phenology of the harbour seal moult was investigated in south-west Ireland in this study. Timing of the moult differed among all cohorts, yearlings began moulting first followed by adult females and finally adult males. The number of seals hauled out was generally positively related to the proportion of seals in active moult. The timing of the moult period was different to other parts of the species' range and should be considered in determining optimal timing of future surveys for assessing populations abundance and trends in Ireland.