The reintroduction of wolves in Yellowstone has been called one of the greatest conservation
success stories of our time. When wolves were restored to the Greater Yellowstone Ecosystem
in 1995-96, scientists and managers made a lot of predictions but did not know what would
actually happen to the ecosystem. All agreed that wolves would likely impact coyotes that had
been, until then, the top dog in Yellowstone and the top predator on elk. Many predictions were
made including a heavily cited 'food pyramid' developed by Time Magazine in consultation with
Dr. Bob Crabtree and Yellowstone Park biologists [active link, pop-up or insert attached image].
Indeed it was a once-in-a-lifetime opportunity to learn how apex carnivores would affect an
ecosystem and we knew that there would be negative impacts on coyotes and elk but the potential
'chain reaction' or tropic cascade was something of a myth at the time. We had been working
cooperatively with park on many projects including a model to predict how wolves would affect
elk and our intensive 6 year study (1989-1995) on coyotes, the species all agreed would be
impacted. The park has been studying elk for decades and we knew that continuing and expanding
the coyote study would allow the wolf-coyote-elk triangle to be a window into how carnivores
change ecosystems. YERC was determined to learn about how ecosystems work from this grand
experiment. We knew that like the formation of the world's first national park, this too could
become a model for the world.
For the two canids resident in Yellowstone, the reintroduction of gray wolves would certainly shake things up. Would it be possible that coyotes would learn to coexist with wolves and continue to thrive in the ecosystem? Or would the larger wolves would kill coyotes and drive the species from the ecosystem. On the other hand, the small group of restored wolves, having little choice in mates, could have bred with the abundant coyotes and produced a hybrid that wasn't a coyote, wasn't a wolf, and certainly didn't satisfy the recovery requirements set forth in the gray wolf recovery plan under the U.S. Endangered Species Act. What's more, little was known about how such dramatic changes would affect the smallest member of Yellowstone's canine heirarchy, it's native red fox population. As our society heralded a new century of conservation with the unprecedented restoration of a large carnivore to a natural ecosystem, we were presented with an opportunity to study the fascinating ecological relationships behind competition.
YERC was there on the slopes of Druid Peak, observing the Druid coyote pack years before the Druid wolf pack was reestablished. We were there when the wolf pens were opened and the group-yip-howls that bounced between resident coyote packs like talking drums were momentarily silenced and then followed by a six-fold increase for over a year. And we were there at the dens, counting coyote pups born into a new generation of coexistence while Yellowstone's own wolf pups were nursing in dens just across the valley. Our 20-year dataset monitoring these dynamic changes is among YERC's most valued assets. The project also provided valuable experience for the nearly 200 field technicians who tracked radio collared animals with compass and telemetry receiver, observed interaction behavior at carcass feeding sites, and collected other important data, as well as valuable insights for managers and other researchers through more than a dozen publications in peer-reviewed journals, newspaper articles and book chapters, graduate theses and dissertations, and technical reports. Its dataset continues to be used to solve real problems for coexistence as we test the ecologically flawed hypothesis behind the 20th Century's status quo coyote management strategy—still killing coyotes across the West to this day—so that lessons learned in Yellowstone can help form better policy affecting coexistence outside the park.
You can find out more about the Wild Dogs of Yellowstone (Canid Ecology Project), and how our findings have been and continue to be used to inform better understanding, better management, and better coexistence with some of nature's wiliest characters.
Coyotes are common in Yellowstone and across the West, while over the last century the species' range has expanded east of the Mississippi River to the Atlantic Coast and north of the Great Plains to the Arctic Circle. They are much smaller than wolves—25 to 35 pounds compared to 80 to 130 pounds—but like wolves they are territorial and belong to social packs. In response to the restoration of wolves, the average coyote pack size as well as the overall number of coyotes has declined, while the total number of coyotes packs has increased as competition with wolves has resulted in more coyote packs on smaller territories.
Wolves are a circumboreal species distributed around the northern hemisphere—like grizzly bears (Ursus arctos), moose (Alces alces), and other mammals in the GYE, this same wolf species can be found across North America as well as Europe and Asia. But in Yellowstone, wolves were eradicated by the 1930s as a result of a misinformed management strategy that valued hunted "game" species, like elk, over the demonized predators, like wolves, that preyed on them. After recognizing the negative effects of overpopulation and the important role that predators have in curbing prey populations, wolves were restored to the ecosystem in 1995 and have thrived there ever since. Those wolves have killed coyotes—nearly one third of the coyotes collared for the Canid Ecology Project were killed by wolves—while also providing food for scavengers that may have otherwise succumbed to one of Yellowstone's harsh winters.
The Lamar Valley and Yellowstone's Northern Range anchor the CEP's study area. Encompassing a heterogeneous mix of environments from sagebrush grasslands to riparian meadows to subalpine forests, the Lamar provides all the habitat requirements for Yellowstone's three wild canines as well as the prey species they depend on. It also provides year-round access to wildlife viewing opportunities, making it a popular destination for wildlife researchers, photographers, and enthusiasts alike.
Throughout the CEP's 20 year history, more than 100 coyotes were captured and fitted with radio collars that transmit a regular BEEP every two seconds on a frequency unique to that collar. We can detect those signals up to two miles away, and with a compass, map, and collection of bearings pointing the signal's direction from a series of set locations, we can triangulate the location of the collared animal on the landscape....
Over the course of a season or even an animal's life time, this provides valuable spatial data on the animal's relationship with its home environment. This data can be used to map out a pack's territorial boundaries by analyzing the home ranges of its members, to identify the types of habitat conditions that coyotes are selecting compared to those that are available to them but avoided by them, and to visualize changes in habitat use patterns from coyote-to- coyote, from pack-to- pack, from season-to- season, and from year-to-year.
We also spent hundreds of hours behind spotting scopes overlooking sweeping vistas of the Lamar, looking for coyotes to observe from a distance, following them with our scopes and recording their behavior in our field notebooks.
The maps produced in this effort were then digitized for GIS, providing geographically synchronized virtual movement paths for all of these observations, accented with details on activity ranging from predation attempts to territorial scent marking along the way. Such detail allows researchers anywhere in the world today—such as our graduate student at the University of Victoria in Canada—to see and understand these stories told in the Lamar Valley many years ago.
More than 20 coyote packs and their individual members were identified and monitored throughout the CEP—a one-of- a-kind dataset that complements observations of Yellowstone's well-studied wolf population as well as other longterm datasets collected by YERC in the Lamar. Longterm datasets like these—those with enough time to capture real trends spanning dynamic events—are necessary for effective Adaptive Ecology.
CEP data was also used to demonstrate YERC's Ecosystem Assessment, Geospatial Analysis, and Landscape Evaluation System (EAGLES), free software designed to make the computational power of resource selection function modeling available to all natural resource managers via a user-friendly GIS-based format. This "heat map" displays places in the Lamar Valley coyotes are most likely to select—and those they are most likely to avoid—based on the distribution of landscape characteristics, prey availability, wolf presence, and coyote observations recorded by the CEP.
We are currently using CEP data to test the antiquated coyote control model used across the West in an effort to staunch an ineffective use of taxpayer dollars, provide helpful information on effectively avoiding the livestock depredation that coyote control is supposed to mitigate, and stop the needless killing of coyotes. With data from the Lamar Valley, we have shown that alpha pack members are rapidly replaced following a vacancy in the pack, especially around the breeding season when territorial instincts are most active. But this goes against the widely-held belief that killing coyotes during the breeding season will reduce the number of pups born. What we found is that the quality of the territory matters more than the quality of the individual coyotes, and that disrupting the social order allows more, smaller packs to use these quality territories. That in turn results in more hungry coyote pups being born than if there was just one large pack occupying the territory. Policy informed by science like this will help save money, livestock, and coyotes.
So what's next for the CEP? Many questions about canine ecology in Yellowstone remain unanswered, and new questions arise everyday. The answers to some of these questions may be buried in the vast CEP datasets. Great opportunities await the prospective graduate students who can tackle these questions: if you are interested in graduate school and would like to find out more about using CEP data for your research, please let us know.