Hopkins Marine Station Student Paper

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(full paper is archived in the Miller Library)

Title: The influence of substrate characteristics on haulout behavior of harbor seals, Phoca vitulina
Student Author(s): Ullmann, Jessica C.
Pages: 30
Location: Final Papers Biology 175H
Date: June 1991
Abstract: Factors influencing the distribution pattern of different ages of hauled out harbor seals were studied for a 5-week period in Spring 1991. Particular emphasis was placed on the impact of substrate characteristics on the observed age distribution. The seals in this area utilize irregularly- shaped offshore rocks for haul out. Aggressive behavior was almost completely absent in this area and seals were never observed battling over haul out space. Substrate features which wer examined included: distance to an escape channel: % total and individual algal cover; size of hauling ground; and degree of incline to reach the hauling ground. These features at least partly resulted in the abserved segregation of ages as adults were limited by the size of the hauling ground, while subadults and juveniles were limited by the % algal cover and degree of incline. Social organization may be an additional influence on the age-structured distributions, but the short term of this study prevented any extensive investigation into the social structure of this population.