While rarely venturing outside sub-Arctic waters, the Atlantic walrus (Odobenus rosmarus rosmarus) has been known to make appearences as far south as Spain. Vagrant animals moving outside their recognized range may be a sign of shifting distributions as a consequence of climate change leading to unsuitable conditions.
In this brief report published in Polar Biology, researchers gathered historic and contemporary records of walrus sightings in temperate Europe to describe vagrancy patterns and investigate trends and drivers over time.
Relying mainly on GBIF-mediated occurrences augmented by searching social media and local newspapers, the authors collected a total of 254 deduplicated sightings. By analysing dates and locations of older sightings, the authors inferred that the sightings between 1923 and 2012 represented no more than 30 individual walruses.
The more recent observations with accompanying photos allowed for identification based on diagnostic characteristics, with which the authors narrowed down the observations between 2012 and 2022 to six individuals, bringing the total number of vagrant walruses to just 36.
The authors were able to calculate daily movement rates, suggesting individuals in fairly healthy condition. Additionally, they observed that males covered significantly larger distances than females.
A generalized linear model showed a significant increase in walrus observations over time, suggesting that more vagrants are reaching temperate Europe due to a combination of increasingly unsuitable conditions and growing population sizes in their natural range.