Phenology of the Pacific Walrus (Odobenus rosmarus divergens) in Coastal Waters of Wrangel Island: The Impact of the Sea Ice Dynamics

Abstract

Data on phenological events in the annual cycle of the Pacific walrus (Odobenus rosmarus divergens Illiger 1815) are presented, and their relationship with the dynamics of sea ice conditions is analyzed based on studies in the area of Wrangel and Gerald islands in the years 1989–1998 and taking into account the literature and unpublished sources. The duration of the feeding period ranged from 79 to 100 days at Wrangel and Gerald islands, from the appearance of the first groups of walruses to the registration of the last animals. The use of terrestrial haulouts during the second half of the 20th century occurred every 1.6–2 years, with the time of concentration of the animals to the departure of the last individuals taking up 33 to 52% of the entire presence period. Significant correlations have been obtained (p < 0.05) between the main parameters of haulout functioning (the beginning of the use of land habitats by walruses, the duration of haulout actions, the number of days the animals spent ashore) with the dates of sea ice disappearance and the duration of total sea ice absence. The results of this study allow recommending the use of phenological dates as an indicator reflecting the dynamics of walrus habitats in the northwesternmost area of the distribution range of the Pacific subspecies.