Polar Bears forced to travel long distances without rest to find solid ground. It highlights the case of a young female that traveled more than 400 km in just nine days.
CANADA – Due to the changes that occur in the quantity and location of sea ice in winter, increasingly polar bears (Ursus maritimus) swimming distances of over 50 kilometers in the Arctic Ocean. For scientists, these great efforts cause loss of body mass and negatively affect the survival of the offspring.
The study, published in the journal Ecography monitored, thanks to GPS collars, 58 adult females and 18 subadult Beaufort Sea, and 59 other adult females from Hudson Bay during the period 2004 to 2012. The results indicate that swimming is becoming more frequent by shrinking sea ice associated with climate change, especially in the Beaufort Sea, where ice has retreated hundreds of kilometers from the coast.
In 2012 the sea ice reached a record low in the Beaufort Sea, 69% of adult females studied swam over 50 kilometers. However, as has been noted the team of scientists, led by the University of Alberta (Canada), in the years when there were fewer thaw, less than 30% traveled long distances to swim.
According to Nicholas Pilfold, first author of the study and a researcher at the Canadian university, these behaviors occur more often because the marine thaw is getting faster and away from the coast in summer. This pattern bears is the footprint of climate change.
During the period studied, polar bears swam an average of 3.4 days and 92 kilometers without rest. The record beat one subadult female that traveled 404 kilometers in nine days swimming. Andrew Derocher study co-author and scientist at the University of Alberta noted that such long-distance swimming is not what the Polar Bears evolved to undergo.
Polar Bear swimming profile
The research highlights that subadult females without calves were more likely to swim long distances. Derocher said that the younger, older or thin are more vulnerable and at risk of drowning. But with more open water, they may increase mortality associated with these behaviors. Females with calves tended to swim less to prevent drowning of their young ones in the cold waters.
Previous studies had already shown that swimming can have an energy cost for polar bears. According to Pilfold, if the trend of sea ice loss remains, more polar bears will need to swim long distances, which can have serious consequences for people living in the Arctic basin.