As the ice caps in the Arctic melt, polar bears unable to prey on seals would turn to other animals such as caribou and snow geese.
This was the conclusion by two scientists at the American Museum of Natural History, after computing the caloric energy derived from the terrestrial food sources and incorporating this with their research. Details of their study was published in the journal PLOS ONE.
“Polar bears are opportunists and have been documented consuming various types and combinations of land-based food since the earliest natural history records,” said Robert Rockwell, a research associate at the Museum’s Department of Ornithology. He had been studying the Arctic ecology of the Western Hudson Bay for almost 50 years.
He added that the analysis of polar bear scats and first-hand observations have shown that sub-adult polar bears, family groups and even some adult males have been consuming plants and animals during the ice-free period.
During ice-free periods, the polar bears are separated from their usual sea-ice hunting grounds and thus are unable to prey on seals.
Currently, specific data on the energetic cost for hunting caribou and geese is unavailable. However, Rockwell and fellow researcher Linda Gormezano have found that there are likely to be more than enough calories available on land for the polar bears to feed on during the ice-free seasons.
In fact, polar bears in Manitoba have been observed to be ambushing caribou. “If caribou herds continue to forage near the coast of Western Hudson Bay when bears come to show earlier each year, they are likely to become a crucial component of the bears’ summertime diet,” said Rockwell.
Another land-based food source are the eggs of snow geese. The impact of this is projected to be sustainable, without detrimental effects to the snow geese population.