Yellowstone’s climate is changing. According to National Weather Service data there are fewer annual subfreezing nights, the growing season is lengthening, summers are warming and winter cold spells are becoming less severe and shorter-lived. And, according to near unanimous consensus among climate scientists who don’t work for fossil fuel companies, this climate change episode is human-induced. What does this have to do with the Yellowstone grizzly bear diet? Plenty. The distribution of plant and animal species in a given ecosystem depends partially upon climate. Other factors include soil, local physiography and interactions with other organisms. But climate is an extremely important factor. Remember, grizzlies are opportunistic omnivores, able to ingest a huge variety of plant and animal material. What’s important to realize, though, is that from a nutritional standpoint, all grizzly foods are not created equal.
In other words, some foods are much more nutritious than others. And if grizzlies lose some of their more nutritious food sources – meaning those with high concentrations of fat and protein – then grizzlies lose. In the Greater Yellowstone Ecosystem pine seeds, moths and dead mammal and fish flesh are or were among the super-rich food sources so vital to the future of the great bear. It is equally important to realize, too, that even if all were just fine in the grizzly food department (it is not), there are many other challenges to the big bear’s future. Like population growth and associated development in and around the Greater Yellowstone. But that’s a topic for another day. In the 4th and final installment of this series, we’ll look at some of the specific food challenges facing Greater Yellowstone Ecosystem grizzlies.