PHENOLOGY OF THE PACIFIC WALRUS (ODOBENUS ROSMARUS DIVERGENS) IN THE WRANGEL ISLAND COASTAL WATERS: IMPACT OF SEA ICE DYNAMICS

摘要

Based on studies in 1989-1998 in the Wrangel and Gerald islands area, with the use of literature and unpublished sources, data on phenological events in the annual cycle of the Pacific walrus (Odobenus rosmarus divergens Illiger 1815) are presented and their relationship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 ice conditions is analyzed. The duration of the feeding period in the Wrangel and Gerald islands from the appearance of the first groups of walruses to the registration of the last animals ranged from 79 to 100 days. The use of terrestrial haulouts during the second half of the 20th century occurred every 1.6-2 years, with the time of the animals' concentration to the departure of the last individuals taking up 33 to 52% of the entire presence period. We obtained significant correlations (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 a total ice absence. The results of this study allow us to recommend the use of phenological dates as an indicator reflecting the dynamics of walrus habitats in the extreme Northwest of the species' distribution range.