Haulout behaviour of captive harp seals ( Pagophilus groenlandicus): incidence, seasonality, and relationships to weather

Abstract

The extent and ecological significance of time spent (“hauled out”) on ice by phocid seals are poorly known. In this study, haulout of nine captive harp seals ( Pagophilus groenlandicus) was monitored and quantified with recorders attached to the seals. The recorders monitored haulout (presence in or out of salt water). Data were collected continuously from September 1995 to October 1996 near St. John's, Newfoundland (47°38′N). Concurrent data on weather (solar radiation, relative humidity, wind velocity, air temperature) were gathered. All seals hauled out throughout the year and haulout was most prevalent during the night. Solar radiation had the greatest influence on haulout during daylight hours, being positively associated with haulout in spring when most seals underwent moult; this trend was reversed in summer. Haulout was negatively associated with wind velocity during spring (moult). High temperature deterred haulout during summer. These findings emphasize the importance of seasonal variation in factors that influence haulout, suggest that haulout by wild harp seals may occur more commonly outside the moulting period than is generally believed, and have implications for the design and interpretation of aerial surveys of harp seals.