Seasonal haulout patterns of crabeater seals ( Lobodon carcinophaga )

Abstract

The haulout patterns of five adult and two juvenile crabeater seals (Lobodon carcinophaga) were documented from February to December 1995 in three areas of the Antarctic. The longest haulout event was 19.2 h (mean=7.9, median=7.8); the longest in-water event was 85.8 h (mean=15.1, median=14.2). In no month were more than 76% of the adult seals in our sample hauled-out simultaneously. Multivariate repeated measures analysis of variance tests revealed no difference between males and females in the daily timing of haulout (P>0.05) between March and August (the only months with an adequate sample); in contrast, haulout timing differed between juvenile and adult seals (P<0.05) except in May. Juveniles spent about twice as much time hauled-out on the ice as adults (38% vs 20%, respectively; P<0.05). Predator avoidance by juveniles is hypothesized to be a possible cause for these differences. In light of these haulout patterns, population surveys of crabeater seals conducted in February, and as close as possible to local solar noon, can be expected to encounter the highest proportion of seals hauled-out on ice.