A recently published scientific study reports on the use of a new technology used to examine the genetic material of over 800 grizzly and polar bears. Of all the bears sampled, eight proved to be hybrids. How did this happen? Will hybridization become more common as climate change affects polar bears’ habitat?
First, let’s address the semantics—are grizzly-polar bear hybrids “grolar bears” or “pizzly bears”? It depends on who the dad is. A grolar bear has a grizzly dad and a polar bear mom, while a pizzly bear has a polar bear dad and a grizzly mom.
The new study, published this week in Conservation Genetics Resources, isn’t the first to identify eight grolar bears. A 2017 research study also identified the eight hybrids all resulting from a single polar bear that mated with two grizzly males in the Canadian Arctic. That polar bear produced four hybrid cubs, and then one of the cubs mated with the same two grizzly males (including her father), producing four more grolar bears.
Will We See More Grolar/Pizzly Bears in the Future?
Polar bears are particularly vulnerable to the effects of climate change, according to the authors of the new research report. “As the climate warms, polar bears will be forced to move to more suitable habitats which are likely to shrink, adapt to the new conditions, or decline in population size,” say Miller et. al. “In addition, warmer climates are likely to result in more frequent contact between polar bears and grizzly bears (U. arctos), with which they can hybridize.”
However, the researchers’ analysis of 371 polar bears, 440 grizzly bears, and eight known hybrids revealed “no novel instances of recent hybridization.” So, while it seems like changing conditions may force the two species into closer proximity, hybridization isn’t on the rise—at least not yet.
Lead image is of a suspected hybrid bear on Victoria Island, Canada. Photo by Jodie Pongracz, Environment and Natural Resources, Government of the Northwest Territories.