Wildlife Watching in America's National Parks: A Seasonal Guide

1. March—Gray Wolves of Yellowstone

21 1 { March Gray Wolves of Yellowstone even in March most of Yellowstone National Park is still covered in deep snow. Although the days are getting longer and the sun is getting higher, spring still seems to take forever to come to the land, at least for some of the park’s residents. At this time of the year, perched between the seasons, life hangs in the balance for the elk, bison, pronghorn antelope, and other large ungulates. Their bodies are weakened and malnourished from the long winter. On top of that, wolves are on the prowl. But it’s never easy for the wolves either as they struggle to take down larger, stronger, and faster prey. This struggle between predator and prey is one of nature’s greatest spectacles. At Yellowstone National Park, in northwestern Wyoming, it is often played out right in front of the wildlife watcher. What’s Remarkable about Gray Wolves? Scientists refer to the wolf as an animal with high “plasticity,” meaning that it can adapt to a wide variety of habitats and prey. Consider that the species historically ranged from the barren tundra of the Arctic to the deep, dark, boreal forests of Canada to the wide-open grasslands of the Great Plains to the scorching deserts of Mexico. All the wolf needed to survive was prey, whether it was musk ox, moose, bison, or javelina. In other words, the wolf is not really a habitat-dependent species in the conventional sense (i.e., vegetation), but rather a prey-dependent species. Historically, where there was prey there was wolves. Spring 22 | remarkably, the wolf’s prey includes some of America’s largest and most dangerous species such as bison and moose. These animals can weigh up to a ton, whereas even the largest wolves may only tip the scale at around 130 pounds. It seems like a mismatch. Yet the wolf has on its side several adaptations—fine tuned by eons of evolution—including endurance, speed, and strong jaws, but most importantly, the cooperation of the pack. It’s the pack that allows wolves to take down prey like the much larger bison and moose. It’s the pack that allows wolves to catch swifter prey such as deer and pronghorn antelope. And it’s the pack that allows wolves to overcome the many sets of eyes in the elk herd. The pack is what separates the wolf from most of North America’s other large carnivores. Yet the wolf has one more trick up its sleeve. In addition to hunting in a pack, the wolf is also a master judge of character. The wolf’s ability to identify injured, sick, old, or otherwise vulnerable prey is often the difference between success and injury. Ironically, by removing unhealthy prey the wolves are what keep the herds of bison, moose, and elk healthy. In many ways, wolves are the stewards of the ecosystems in which they occur and one of nature’s most remarkable animals. Once persecuted almost to the point of extinction in the lower forty-eight states, wolves have made a dramatic recovery in some areas. (Photo by Daniel S. Licht) March–Gray Wolves of Yellowstone 23| Wolf Ecology Scientists are just now beginning to understand and appreciate the important and complex role wolves play in ecosystem health. Many biologists now consider the wolf a keystone species, that is, one that influences many other species in the ecosystem. Wolves can affect ecosystems either directly, by killing prey species and therefore keeping prey populations in check, or indirectly. Consider what science has learned from the reintroduction of wolves to Yellowstone National Park. Prior to the reintroduction of wolves to Yellowstone National Park, the park’s elk herd had for decades been overabundant, which in turn led to degradation of the park’s plant communities. Plants such as aspen and willow were not reaching maturity due to the heavy and relentless elk browsing. The reintroduction of wolves in 1995 has helped reduce elk numbers to a level more in balance with the ecosystem (about 90 percent of the diet of Yellowstone wolves is elk). elk are no longer viewed as overabundant . But there’s more to the story than the numbers. Watch how the two species interact. Just the presence of wolves tends to keep the elk alert and on the move, which is good for the vegetation. Prior to the reintroduction Gray...