For the first time in history, the researchers traced one of the most important (and crucial) periods of the life of polar bears: the maternal denwhere females give life to theirs puppiesremaining with them in early childhood. The work, conducted thanks to an innovative system, was guided by theUniversity of Toronto (Canada).
The pregnancy and early childhood of polar bears
As we read on the Polar Bear International websitebetween April and late June, the polar bears are looking for female companions following the traces left by the legs and the coupling takes place on marine ice. But the fertile eggs do not implant themselves before autumn and only if the female has quite fat to support herself and her puppies during the long period of den.
After nourishing during the summer and autumn, taking as much weight as possible, pregnant females are preparing to enter the maternity lairs to give birth to their puppies. To build one, the female digs a small cave in a pile of snow, just large enough to allow it to turn around, then wait for the snow to close the entrance tunnel and completely hide the den.
The female gives birth from 1 to 3 puppies, with more common twin parts, generally in December, and the family remains in the den until spring. While in the den, the mother Orsa, going to lose about the Half of your weight: It is dedicated to breastfeeding and taking care of his puppies.
The den protects puppies from the icy climate and the breastfeeding of the mother allows them to grow 20 times their size in a few months. After this first phase, the female returns to hunt, while she wanders in the den for a few weeks, entering and leaving.
It is known as the time that the mothers of polar bears spend in their lairs affects the probability of survival of puppies. However, the reason why they remain so long and what they are doing still remains not very clear, also because i tracking devices Generally used by researchers they have never been tested with real bears.
In fact, historically, researchers have Study the den with Binocolithen with remote cameras and now they mainly use satellite collars capable of tracing position, activity and ambient temperature.
But all these methods have their limits: in particular collars, even if they are becoming more important because they can monitor the movements of polar bears for several years, most of them collects data only every few hoursnot revealing itself in reality ideal for observing more minutes or short trips out of the den.
The new tracking system
In this new study, the researchers have studied bears for six years, using satellite collars on 13 members of the polar bears subpopulation of Barents seasimultaneously by locating and installing cameras outside nine la burning in the islands Abbishin Norway. In this way they discovered that estimates on reaching the key stages of the den Sometimes they have differ for several days more than a weekand these differences depended on the exclusive use of the data of collars or cameras.
For this, scientists, every time they collected the collar data, there they combined the exact image on the camera To confirm what bears were doing, thus generating three statistical models, in which other researchers can enter the collar data to predict not only what animals are doing, but but What they will probably do.
The models proved to be able to predict when the bears will come out for the first time, when they come out of the den and when they are definitively left.
A model was also useful to predict how external factors such as temperature influence the behavior of mothers and puppies.
Collars are very effective in identifying these wider behaviors, such as when bears come out for the first time from the den and when they leave. We found out that they corresponded quite well to what we saw on the camera – explains Louise C. Archer, first author of the study – but it was Difficult to distinguish at fine scale behaviors we saw on the camera
The results
Combined observations have shown that:
These data, overall, suggest that these weeks around the den are mainly served for puppies for acclimatize the outside world and support other searches that have discovered that this phase is crucial for puppies, influencing theirs a decisive way probability of surviving.
The importance of monitoring polar bears
These wonderful animals are one of the symbols of climate change And not surprisingly. A recent study of the same group, in fact, demonstrated how the full -fledged decline of their populations is connected to the reduction of marine ice caused by climate change.
The Arctic is a rapid change area – explains Archer – Very sea ice is losing themselvestherefore seeing what polar bears are doing and how they are responding to these changes can indicate what to expect in other parts of the Arctic in the future. That’s why we are so busy in an attempt to build this data set and continue to monitor bears in this region
And the Arctic, for its part, is a important target for climate change studies in general.
The Arctic is heating two to four times faster than the rest of the worldhuman beings are expanding in areas that could be important for the polar bears lair and we know they are sensitive to ailments during this period
We need healthy puppies To support the populations – concludes the researcher – we are trying to develop tools to monitor and better understand their behavior, so as to be able to protect more effectively
The work was published on The Journal of Wildlife Society.
Sources: University of Toronto / The Journal of Wildlife Society
