Climate Change Pressures Polar Bears to Find New Prey

As climate change progresses, researchers notice a change in the diet of Polar Bears. A shift from seals to goose eggs could spell trouble for ecosystem balance.

Normally, Polar Bears feed on Ringed Seals by stealthily sneaking up on the ice sheets to catch their prey. But, as climate change progresses and sea ice melts, this natural behavior is subject to change; Polar Bears could begin to seek out and become dependent on different food sources. A study published in the Journal of Animal Ecology has an unnerving story to report. Turns out, behavioral changes caused by climate change might be making Polar Bears invasive predators.

Since sea ice cover has been decreasing, Polar Bears have a more difficult time hunting the way they used to. In order to adapt, many Polar Bears are staying near goose nesting grounds. The bears can easily wander through the nesting grounds and snatch any goose eggs they find. Remember, a 1000lb adult male Polar Bear is evolutionarily accustomed to the calories of a Ringed Seal—such a hefty individual needs a lot of goose eggs to survive. The researchers noted:

But it is…obviously, a disaster for the geese who now face a predator not previously experienced. The impacts of a drop in geese numbers may affect more than just the birds themselves.


Fox cubs typically eat Snow Geese eggs, but if Polar Bears cannot access their preferred food, then goose eggs might be their next best option. Credit: Island Conservation

Herein lies the problem: Polar Bears are eating a huge proportion of goose eggs and Snow Geese are not evolutionarily prepared for this level of predation on their nests. The problem has cascading consequences: goose eggs are an important food source for fox cubs. With Polar Bears newly on the hunt for goose eggs, they are likely to be outcompeted.

Changes in the food web of this magnitude could be ecologically devastating. Researchers believe the shift in predator-prey interactions can impact the grasslands where geese and reindeer graze. Without an abundance of geese, the tundra could see its own shift in natural cycles. As climate change progresses and species begin to adapt their behaviors, food web changes could become a common and serious problem.

Featured photo: Ringed Seal. Credit: Natalie Tapson
Source: IFLScience

About Emily Heber

Emily is a recent graduate from UC Santa Barbara with a BS in Zoology. As a student, she discovered that she had a passion for the conservation of endangered species and their ecosystems. Her background in informal education has allowed her the opportunity to share her passion for animals with others, something she seeks to continue doing while working with the communication team. In her spare time, Emily enjoys exploring the amazing hiking trails found in Santa Cruz and tries to SCUBA dive whenever possible. Emily is excited to join the Island Conservation team and to help share the amazing work that is being done here.

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