Seasonal movements and hauling site fidelity of harbor seals, Phoca vitulina Richardsi, tagged at the Klamath River, California

Hauling site fidelity, movement patterns, and the proportion of harbor seals hauling out were examined for one year by radiotagging 12 seals in the Klamath River, California. Hauling site fidelity was highest during the spring and summer months, with 42% of the tagged seals traveling from nearby hauling grounds to forage in the river. The majority of seasonal movements and dispersals originated during winter months, with subadult seals exhibiting a greater tendency for movement than adults. Seasonal movements coincided with the abundance of common prey items, pupping, breeding, and moulting activities. Tagged female seals made a significantly larger proportion of seasonal and local moves than males. Seals hauled out an average of 56.1 ± 2.8% (standard error) of the days in April and 63.6 ± 5.5% (S.E.) in May. Based on resightings, a minimum of 56.4 ± 3.1% (S.E.) and 65.1 ± 12.8% (S.E.) of the study area harbor seal population hauled out daily in April and May. The maximum recorded count corrected for the proportion of animals hauled out suggests that from 522 to 778 harbor seals were present in the study area at the peak of the season in May 1983.