Researchers studying how polar bears have been coping with the changing sea ice patterns have made a great recent discovery: The Arctic predators, struggling to catch their usual meals, can turn to poaching seabird eggs.
The researchers have been observing the bears in the Norwegian-owned Arctic island territory of Svalbard since a sudden loss of sea ice in 2006 in the area. The researchers attached tracking devices to 60 ringed seals and 67 female polar bears before and after the decline.
The researchers found that polar bears have to travel much farther during the summer and autumn to reach the sea ice where the seals congregate, making the apex predators less likely to encounter their primary food sources, forcing them to look for alternatives.
“Polar bears now move greater distances daily and spend more time close to ground-nesting bird colonies, where bear predation can have substantial local effects,” the researchers said.
Charmain Hamilton, who led the research team from the Norwegian Polar Institute, told that the change to the coastline means bears that did seek out the seals were forced to try swim up to their prey without being noticed, then leap out of the water to catch them. This, Hamilton told, has a much higher failure rate as opposed to their usual hunting method, which is more like stalking.
The newfound tendency to devour birds’ eggs instead isn’t just bad for the bears, who struggle to digest them, but also to other predators that rely on them as a food source.
Research elsewhere in the Arctic, conducted by the researcher Jouke Prop at the University of Groningen, found that polar bears that do set upon bird colonies need to devour massive amounts of eggs to get the same amount of nutrients, leading to some colony populations falling by as much as 90 percent.
“If numbers decline – which is to be expected – this will have an impact on the whole terrestrial ecosystem. For instance, Arctic foxes depend on young geese as food. Reindeer food intake is facilitated by geese grazing the tundra,” Prop said.