Collars are Key to Wolf Studies
Wolves range far and wide throughout Yellowstone’s 2.2-million acres of dense wilderness, yet the Park’s wolf population is one of the most studied populations of wild wolves ever. It is radio collars that enable the monitoring of multiple wolf packs across this vast area. Thanks to sponsorship donations from generous Friends of Yellowstone, the Yellowstone Wolf Project is able to place 25-30 collars on wolves annually. Both VHF and GPS collars are deployed, providing the basis for nearly all other aspects of Yellowstone’s wolf research program.
VHF (Very High Frequency) collars are used when researchers can get closer to wolves and track them. GPS (Global Positioning System) collars work with satellites and store information for later retrieval, so they can be used to track wolves at great distances.
In a recent interview with Yellowstone Wolf Project Leader Doug Smith, on the occasion of the 15th anniversary of wolf reintroduction in the Park, he called collaring the “heart and soul of the Wolf Project.” Read more in this special anniversary issue of the Yellowstone Park Foundation print newsletter>>
So, you may be wondering, what specific types of information are collected from collared wolves? Several of the ongoing studies performed by the Yellowstone Wolf Project rely on data collected via wolf collars.
Predator–Prey Relationships: A major objective for Yellowstone wolf research is the examination of wolf-prey relationships. Semiannual, 30-day winter studies -- ongoing for the last 15 years -- are designed to record predation patterns. More recently, the study of predation patterns in summer, when wolves range more widely, has been made possible by using data that is downloaded from GPS collars. The data allows researchers to quickly locate and study kill sites to determine predation rates, total time wolves feed on carcasses, percent of kills consumed by scavengers, and characteristics of wolf prey (e.g., sex, species, nutritional condition).
Population Dynamics: Collar data has been proven to be the best, most accurate way to get an annual count of wolves. The collars give year-round information about population dynamics such as births and deaths, as well as immigration to, and emigration from, the Park. Researchers also rely on the data to help determine territory size and use, reproductive success, cause-specific mortality, survival, and other life history patterns.
Wolf Dispersal: The ecological, demographic, and genetic implications of the dispersal from a pack are an important research focus for Yellowstone wolf biologists. Collar tracking information helps them understand basic demographic patterns of dispersal (age, sex, distance, season) along with the influence of wolf density, pack structure and size, and kinship. Most importantly, it allows researchers to “follow” wolves as they disperse out of Yellowstone National Park to see how the different endangered species recovery areas are connected – one of the key criteria for delisting.
Wolf Spatial Dynamics: Thousands of wolf radio locations, both VHF and GPS, have been gathered since wolves were reintroduced in Yellowstone in 1995. Rigorous analyses using these locations have begun examining many questions concerning habitat use and territoriality. Year-to-year changes in territory use are being related to variables such as elk density and distribution, pack size, reproduction, and wolves killing other wolves. Researchers also analyze how wolf territories differ in the summer compared to winter, as a result of seasonal movement of elk herds.
Collaring operations are critical, but expensive. They involve aircraft, staff time, tracking equipment, and extensive lab and data analysis. One of the most significant ways the Yellowstone Park Foundation has contributed to the ongoing monitoring and research of Yellowstone wolves is through the Wolf Collar Sponsorship program. The Foundation launched this program in 1997 to allow donors to participate directly in ongoing wolf research.
All photographs courtesy of the National Park Service.