Polar Bears Losing Weight, Having Fewer Cubs Due to Retreating Sea-Ice – The Weather Channel


Posted: February 19, 2020 at 8:48 am

Polar Bear

Increasingly warm climatic conditions have led to the constant retreat of sea-ice in both the polar regions of the Earth. The threat to the icy habitats of Arctic and Antarctic regions, and the animals that dwell there, is unprecedented.

Now, a new study has highlighted the severe impact of the retreating sea-ice on the reproductive, nutritional and behavioural lifestyle of polar bears, which have become a poster-child of climate change. The study shows that due to climate change and resultant loss of sea-ice, polar bears are losing weight and are producing fewer offspring over the past two decades.

The International Union for Conservation of Nature (IUCN) has listed polar bears under the red list of vulnerable animals, which faces long-term survival threat due to global warming. With less than 25,000 mature individuals left on the planet, the survival of the polar bear population largely depends on the extent of sea-ice available.

The study was performed on polar bears living in the Baffin Bay area of the North Atlantic Ocean off Greenland. As soon as Spring starts, polar bears shift their base to the land due to reduction of sea-ice. The coast of Baffin Island is generally the last place in Baffin Bay to lose sea ice in summer. Sea-ice not only felicitates seasonal movement and mating activities for polar bears, but also provides food in the form of ringed seals and bearded seals.

Bears in this area give us a good basis for understanding the implications of sea ice loss, said the lead author of the study, Kristin Laidre, in a statement.

Polar Bears losing weight

The study, conducted by University of Washington, has shed light on the health and reproductive changes of the polar bears with respect to sea-ice loss. Our analyses indicate that reduced sea ice availability has been associated with longer times spent on land, reduced body condition, and reduced reproductive success, stated the paper published in the journal Ecological Applications.

As polar bears spend more time on land, due to global warming, the duration of their fasting increases and it puts their life cycle in imbalance. During their stay on land, polar bears mostly depend on the fat stores in their bodies. As this seasonal starving period extends, it results in more and more weight loss.

To assess the changing fat trends of the bears, researchers quantified body fat on a scale of 1 to 5. The observation of body fat was done on the basis of physical capture, biopsy darting and aerial views.

The findings revealed that the bears' body health and weight was majorly linked to the availability of sea ice. The results also show that polar bears are spending at least an average of 90 days on land over the past few years, as against just 60 days spent on land during the 1990s.

Change in reproductive patterns

Another major outcome of the study was that the female polar bears are producing less offspring compared to the 1990s, when the extent of sea-ice was much larger. The research underlines the fact that when the polar bear is in good health, the size of offspring is normal and the number of offspring is more. However, with more time on land, the pregnant females rely mainly on the body stores to support gestationeffectively reducing the health and number of offspring.

We show that two-cub litters usually the norm for a healthy adult female are likely to disappear in Baffin Bay in the next few decades if sea ice loss continues, Laidre said.

The reproductive pattern of the polar bears was analysed by comparing the data of female polar bears from the 1990s. For this, litter size and the general health of the polar bear was quantified.

For the study, the researchers used techniques of satellite tracking and visual monitoring of polar bears. They studied the satellite telemetry data of 38 tagged adult female polar bears between the years of 20092015 and compared it with the data collected from 19911997 of 43 adult female polar bears living in the Baffin Bay subpopulation.

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Polar Bears Losing Weight, Having Fewer Cubs Due to Retreating Sea-Ice - The Weather Channel

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