U.S. Researchers Find That Polar Bears Are Unlikely To Thrive On Terrestrial Foods

polar-bear

New research has revealed that polar bears are unlikely to thrive on land-based foods.

A team of scientists led by the U.S. Geological Survey found that polar bears may be eating terrestrial foods, including berries, birds, and eggs, but, these foods cannot replace their traditional food of marine mammals, including ice seals.

“Although some polar bears may eat terrestrial foods, there is no evidence the behavior is widespread,” said Dr. Karyn Rode, lead author of the study and scientist with the USGS. “In the regions where terrestrial feeding by polar bears has been documented, polar bear body condition and survival rates have declined.”

The study, published in Frontiers in Ecology and the Environment, shows that terrestrial habitats are already occupied by grizzly bears. They are a potential competitor as polar bears are displaced from their sea ice habitats.

“The smaller size and low population density of grizzly bears in the Arctic provides a clear indication of the nutritional limitations of onshore habitats for supporting large bodied polar bears in meaningful numbers,” Rode said, adding that “grizzly bears and polar bears are likely to increasingly interact and potentially compete for terrestrial resources.”

According to researchers, fewer than 30 individual polar bears were observed consuming bird eggs from any one population, which typically range from 900 to 2,000 individuals.

“There has been a fair bit of publicity about polar bears consuming bird eggs. However, this behavior is not yet common, and is unlikely to have population-level impacts on trends in body condition and survival,” Rode added.

Scientists found that polar bears are consumers of the highest lipid diet of any species, which provides all essential nutrients and is ideal for maximizing fat deposition and minimizing energetic requirements. Potential foods found in the terrestrial environment are dominated by high-protein, low-fat animals and vegetation. Polar bears are not physiologically suited to digest plants, and it would be difficult for them to ingest the volumes that would be required to support their large body size.

“Focused research will help us determine whether terrestrial foods could contribute to polar bear nutrition despite the physiological and nutritional limitations and the low availability of most terrestrial food resources. However, the evidence thus far suggests that increased consumption of terrestrial foods by polar bears is unlikely to offset declines in body condition and survival resulting from sea ice loss,” Rode said.

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Drew is a regular contributor covering trending topics.