Here's how they do it: Adult pine beetles burrow under the outer bark of conifer trees and lay their eggs. Later, these eggs hatch into hungry beetle larvae, which chow down on the tender inner bark, causing serious damage and often death to the tree. This is bad news for the grizzly bear, which feeds on one of the beetle's favorite targets: the whitebark pine. Whitebark seeds are a major source of calories for grizzly bears, particularly in the fall before they go into hibernation.
While global climate change is a major threat to plants and animals all over the world, the mountain pine beetle is actually benefiting from rising temperatures. Recent research, including a study published in the journal Ecology and a study published in Proceedings of the National Academy of Sciences, suggests that the beetles thrive in warmer temperatures and with less rainfall, two expected impacts of climate change in the western US. This is already apparent, as scientists have noticed the beetles reproducing earlier and spreading farther than ever before, leading to more frequent and severe infestations around the West.
As the climate continues to become warmer and drier, pine beetles will likely continue to multiply and expand their range, which is bad news for conifer forests and the vulnerable grizzlies. Although bears are good at adapting to food shortages and finding other things to eat, this ability often drives them close to human civilization in search of snacks — but end up facing a hunter's gun instead.
