Should You Fear the Pizzly Bear?

In New England today, trees cover more land than they have at any time since the colonial era. Roughly 80 percent of the region is now forested, compared with just 30 percent in the late 19th century. Moose and turkey again roam the backwoods. Beavers, long ago driven from the area by trappers seeking pelts, once more dam streams. White-tailed deer are so numerous that they are often considered pests. And an unlikely predator has crept back into the woods, too: what some have called the coywolf. It is both old and new — roughly one-quarter wolf and two-thirds coyote, with the rest being dog. The animal comes from an area above the Great Lakes, where wolves and coyotes live — and sometimes breed — together. At one end of this canid continuum, there are wolves with coyote genes in their makeup; at the other, there are coyotes with wolf genes. Another source of genetic ingredients comes from farther north, where the gray wolf, a migrant species originally from Eurasia, resides. “We call it canis soup,” says Bradley White, a scientist at Trent University in Peterborough, Ontario, referring to the wolf-coyote hybrid population. The creation story White and his colleagues have pieced together begins during European colonization, when the Eastern wolf was hunted and poisoned out of existence in its native Northeast. A remnant population — “loyalists” is how White refers to them — migrated to Canada. At the same time, coyotes, native to the Great Plains, began pushing eastward and mated with the refugee wolves. Their descendants in turn bred with coyotes and dogs. The result has been a creature with enough strength to hunt the abundant woodland deer, which it followed into the recovering Eastern forests. Coywolves, or Eastern coyotes, as White prefers to call them, have since pushed south to Virginia and east to Newfoundland...In Maine, Minnesota and New Brunswick, Canadian lynx have lately produced cubs with the more southerly bobcat. A Southern flying squirrel has pushed north into southern Ontario and begun mating with its larger, boreal cousin. The best-known examples of this process are the polar bear-grizzly hybrids, sometimes referred to as grolar or pizzly bears, four of which have been shot by hunters in recent years; genetic testing indicated that one of them was a second-generation animal. There have been several other sightings of bears suspected of being hybrids, and this spring a mother thought to be one, accompanied by grizzly-looking cubs, was captured (tests are pending). Better management of grizzly hunting may have also contributed to this mixing by enabling males to advance into polar-bear country. “A warming Arctic is not a bad thing for grizzly bears,” says Andrew Derocher, a biologist at the University of Alberta. We might regard these developments as unintended consequences of intensifying human activity on the planet. Yet in the past decade or so, scientists have discovered that the genomes of many species — far more than previously thought — contain what seem to be snippets of DNA from other species, suggesting they were shaped not only through divergent evolution but also by occasional hybridization...more