. According to a recent study, there have been fewer hunting seals in the Arctic, which means that polar bears are forced into raiding the eggs of seabirds. Researchers from the Netherlands, Germany and France, as well as Poland, claim that polar bears now raid bird nests one month earlier than their 10 year ago. In Frontiers in Ecology and Evolution, the researchers stated that Arctic temperatures are rapidly rising. Current changes in the Arctic’s habitat are being caused by the shrinkage of the sea ice. The region’s most powerful predator, the Polar Bear (Ursus maritimus), relies on sea ice to hunt seals. The researchers wanted to verify whether the theory that animals hunt other food during longer periods of ice are true. Spitsbergen’s polar bears eat eggs from a colony of Barnacle Geese. As their nests empty, the geese look helpless. (Credit to Jouke Prop. They collected and analysed time-series data on polar bear observations at four sites in Spitsbergen, (Svalbard), and one east Greenland. The 1970s have seen a significant increase in summer bear occurrence. This is measured by the probability of seeing bears during the day and how many days there are bear presence. In the area studied, the increase in polar bear sightings coincided with shorter sea-ice season lengths and less snow in spring. According to the authors, “This led to a strong inverse relation between bear encounters on the land and length of sea ice seasons.” Indirect relationships can also exist. The breeding success of birds may be threatened by polar bears. According to the research, direct observation of nest predation revealed that the breeding success and viability of the common eider, glaucous, and barnacle geese could all be affected. The bears’ attacks on nests are strongest when they arrive before birds hatch, which is more than 90% for all nests. Jouke Prop (lead author), is a researcher at the University of Groningen’s faculty of Arctic Studies. He said that “when a predator arrives on the scene, it may disrupt the delicate balance of predators and prey.” “Polar bears are now colonizing areas along the coasts where they were absent for many years is an example. Studies from Canada also showed similar results regarding climate change and habitat changes. In an abstract in the journal, the authors conclude that “the increasing presence of bears on the ground in the summer is a result of behavioral adaptations of a small portion of the population to deal with reduced hunting ranges on the sea ice.” Frontiers of Ecology and Evolution. Publication 25 March. 2015. DOI: 10.3389/fevo.2015. 00033.
