In 2006, Jim Martell from Idaho, was hunting in the high arctic and shot the first confirmed grizzly bear – polar bear hybrid. There had been unconfirmed reports of rare hybrids in the past, but this was the first confirmed instance. That the two species of bear could successfully mate was proven in captivity in 2004 when two hybrid cubs were born in a zoo.
Since 2006 reports and photographs of confirmed hybrids are on the increase. In addition the barren ground grizzly bear population is clearly moving northward into the high arctic as the climate warms. Climate warming has been especially prominent at the poles. There is also some indication the polar bears are moving southward in search of food on land off of the diminishing sea ice. These movements will, of course, put the two bears in proximity and allow for some mating.
Recent genetic research shows that polar bears are a relatively new species on the geological time scale, and that they emerged from brown bears (grizzly bears) a couple million years ago. Now they might be turning back into grizzlies and creating a new species that might be more suitable to make a living and reproduce in the rapidly changing Arctic.
Observations of hybrids so far show that their size and other physical characteristics are intermediate between polar bears and grizzlies. In terms of their behavior, the “compromise” falls to acting more like polar bears than grizzlies.
An overview of the march of grizzlies north and the increasing number of hybrids is now making it into the media. This article gives an overview. Unusual Number of Grizzly and Hybrid Bears Spotted in High Arctic. By Ed Struzik. Yale Environment 360.
As hybrid bears appear, the question is raised whether this is a beneficial change for bears in general in the High Arctic? Hybrid animals, as opposed to plants that often show “hybrid vigor,” are often less able the either of their parent species. However, as with coywolves they might be more adaptive in a new environment where they appear — the changed Arctic. Polar bears are much more carnivorous than grizzly bears, and the fish and seals of the High Arctic are loaded with many human released pollutants which are carried north and fall out in what we used to think was a near pristine environment. If hybrid bears, eat lower on the food change as grizzlies do, their health and reproduction might benefit, further increasing their numbers. First generation hybrid animals often show hybrid vigor too, but sometimes subsequent generations show genetic depression, especially with grizzlies, hybrids, and polar bears giving each generation of hybrids different amounts of polar bear, hybrid, or grizzly bear genes.
Because climate change does not stop unless humans stabilize their effect on the climate, it might be that no kind of bear (and most other animals and plants too) will be well adapted.