Food ends with polar bears

Scientists from the University of Toronto observed an almost 50 % decrease in the polar bear population (Ursus Maritimus) living in the western part of the Hudson Bay in 1979-2021. According to experts, this is associated with a decrease in sea ice, which causes the hunting period to become shorter and bears are not able to obtain enough food. The article on this subject was published in the journal “Science”.

– Loss of sea ice causes the bears to spend much less time, hunting for seals, and they starve more on land – said Louise Archer, the main author of the study. – Lack of adequate amount of food negatively affects their energy balance. Malnutrition causes problems with reproduction, it also leads to a reduction in the survival of young people and ultimately to the decrease in the population – she added. The energy balance is the difference between energy profits and its losses.

The model developed by scientists monitors the amount of energy that bears get from seals hunting and the amount of energy they need for growth and reproduction. The uniqueness of this model is that He follows the full life cycle of individual polar bears – from birth to adulthood – and compares it with data from 1979-2021 regarding monitoring of the population of this species in the western part of the Hudson Bay. During this period, the population decreased by almost 50 percent. Monitoring data also shows that during these years the average bear size has also dropped. For example, the body weight of adult females decreased by an average of 39 kilograms, and 26 kilograms of one -year young.

The model developed by scientists ensures a strict matching to the monitoring data, ensuring a thorough assessment of what will happen with the polar bear population in the face of the progressive loss of sea ice. – Our model goes a step further than the statement that there is a correlation between the decrease in sea ice and the fall in the population – said Péter Molnár, co -author of the study. – The model shows what happens when there is less ice, less time for feeding and generally less energy – he added.

According to scientists, young individuals will feel the most progressive climate change, but it also depends on them the fate of a given bear population. Louise Archer claims that shorter hunting periods make mothers malnourished and produce less milk. This, in turn, threatens the experience of young people, which, if they do not gain much weight during the first year of life, they die.

Mothers also give birth to fewer young people – write researchers. Monitoring data show that the size of the young broom has dropped by 11 percent compared to data from 40 years ago. In addition, mothers keep their young longer with them, because they are not strong enough to live on their own.

“It's quite simple, the survival of the young directly affects the survival of the entire population,” Archer added.

The population of polar bears living in the western part of the Hudson bay has long been considered a reference point for the entire population of this species. Since the Arctic warms up at a very fast pace, other bear populations may decrease.

“This is one of the polar bears most emergenated south and was monitored for a long time, so the data is reliable,” said Molnár. – There are all reasons to think that what is happening with polar bears in this region will also become with polar bears in other regions. This model basically describes their future – he emphasized.