Interannual site fidelity by Svalbard walruses

Area of Science:

• Marine biology
• Arctic ecology
• Conservation science

Background:

• The Arctic is undergoing rapid sea ice decline, impacting ice-dependent species.
• Understanding the effects on endemic marine mammals like walruses is crucial for conservation.

Purpose of the Study:

• To examine the interannual seasonal movements and habitat use of male walruses in relation to sea ice coverage.
• To investigate the drivers of walrus migration and their site fidelity.

Main Methods:

• 40 male walruses (Odobenus rosmarus) were tagged with GPS loggers in the Svalbard Archipelago.
• Interannual movement data (1-6 years) were analyzed for 12 individuals.
• Movement patterns were correlated with sea ice concentration and daylight length.

Main Results:

• 11 walruses showed clear seasonal migration between foraging and breeding areas.
• Individuals demonstrated high site fidelity, returning to the same areas annually.
• Annual swimming distances ranged from 5225-10,406 km, with consistent individual distances year-to-year.
• Migration timing was not affected by sea ice or daylight, suggesting endogenous control.
• Movement paths became more tortuous in heavy sea ice areas, potentially indicating searches for open water (polynyas).

Conclusions:

• Walruses exhibit strong individual site fidelity and consistent migratory phenology, likely driven by internal cues.
• Despite variable sea ice conditions, their migratory routines remain fixed.
• Future climate change impacts on Arctic sea ice may pose significant challenges to established walrus migration and habitat use.