NPS photo / Steve Arthur Generally wolves stand about 2 ½ feet tall at the shoulders. Adult females weigh an average of 88 pounds. Adult males weigh 105 pounds on average, but can weigh up to 130 pounds!
The average pack size is between 4 to 5 wolves.
Wolves are carnivores, which means they hunt other animals for food. This includes moose, caribou, sheep, rodents, hares, beavers, and birds. Wolves will also scavenge and take advantage of carrion. Wolves have also been observed taking advantage of other seasonally available foods in Denali, such as blueberries.
In Denali, caribou are the main prey source for wolves, but they also prey on moose and Dall sheep. These animals (with hooves) are often called ungulates. How easy it is for wolves to catch and eat ungulates is related to how easy it is to catch them. We call this their vulnerability to predation. Vulnerability of caribou to predation is largely related to total snow fall (Mech et al. 1998). In a winter with above-average snowfall, it is more difficult for caribou to move and find food. The extra effort that it takes for the caribou to survive might affect their health and breeding success. It is also harder for them to run and escape predators. On the other hand, in winters with low snow cover, it is easier for caribou to move, find food and escape predators. Traveling along the Denali Park Road offers a unique opportunity for visitors to see wolves in the wild. In general, the odds of seeing a wolf are very unpredictable. There are a number of factors that influence whether or not you might see a wolf on any given day. If a wolf pack has a den or homesite (an area of high use) near the park's sole road in a given year, wolves are more likely to be seen in that area. However, in some years, no packs will den near the Denali Park Road, meaning that wolf sightings are driven by the unpredictable movements of individual wolves as they hunt and travel throughout their territory. If wolves have made a kill near the road, they will often be more visible in that area for several days, but this window of opportunity is brief as the wolves will soon move on. Areas of the park that have more open terrain with low vegetation, such as Sable Pass, Highway Pass, and Thorofare Pass, make it easier to see wildlife in general, including wolves, so be sure to keep your eyes open in these sections. Like many species, wolves tend to be more active in the mornings and evenings, although they can be seen at any time of day. Keep in mind that Denali is a very large park and our wolves have large territories—an order of magnitude larger than in other areas of the United States. As such, seeing a wolf is a relatively rare and special opportunity. We strive to reduce the impact of human activities to wolves. This is especially important during sensitive periods (such as during breeding and pup rearing). Areas around known den sites or rendezvous sites are closed to hiking access, as per our wolf management plan. Please respect all closure signs in the park. Opportunities for working directly with the wolf project are limited, especially field work. This is because the majority of our “field work” is actually aerial tracking conducted by experienced pilots and trained observers. However, we do occasionally have opportunities for volunteer work, primarily during winter. Most of the volunteer opportunities in the winter are focused on data entry tasks. Applicants with an interest in helping with data entry and analysis or applicants with specific data analysis skills can contact the park volunteer office.
Any internship or volunteer position in the park requires being signed up as a National Park Service volunteer. Learn more about how to be a volunteer. We consider potential volunteers/interns that are U.S. citizens or international applicants that have the appropriate visa to volunteer for the U.S. National Park Service. Find more information on the required visa and planning process for international applicants. You can apply to conduct research in our National Parks. A Scientific Research and Collection Permit (https://irma.nps.gov/rprs/) is required to conduct research on all National Park Service (NPS) lands and all proposed research is subject to an application review process. Learn how to create a successful proposal.
In Denali large wolf territories, limited accessibility, extreme climate, and varied terrain can make it challenging or impossible to conduct ground-based field studies without considerable man-hours. Most of the wolf observations for our long-term monitoring program are conducted through aerial tracking flights.
The areas that wolf packs habitually occupy and defend from other wolves are known as territories. In Denali, wolf territories range up to 1600 square miles or the size of Rhode Island, which are some of the largest territory sizes recorded for wolves around the world.
Wolf density is a way to estimate how many wolves are in a given area (i.e. study area). These estimates can change quite a bit depending on how the study area size is determined. Because researchers may calculate the size of a study area differently, densities cannot always be compared between studies. Technology and funding can also change significantly throughout a long-term monitoring project. In Denali’s wolf project, the methods for obtaining home ranges and study area estimates have changed throughout the years. We still are not sure how comparable densities are from year to year. Some biologists prefer to use average pack size to compare trends in wolf numbers in a region.
Wolves exist at a wide range of densities throughout their range. It is not uncommon for wolf populations in arctic regions to have densities less than 5/1000 km2 (reviewed in Fuller et al. 2003). Usually, wolf densities are different between populations because of differences in how easy it is to find and catch prey. There may be less prey in a certain area, or prey may be harder to catch. Both the number of prey in and area and how easy they are to catch determine how much prey is available to wolves to eat. Wolves tend to hunt old, young and vulnerable prey because it takes less energy, is more likely to be successful, and is less dangerous to the wolves than preying on a healthy adult.
When estimating prey biomass in an area, it is important to remember that not all prey biomass is available to the wolves as food. The more prey available to wolves, more wolves will live in a certain area. While this is a useful trick to know, even this is not always accurate. Sometimes wolf densities can still vary even with similar prey availability (Fuller 1989). Sometimes scientists cannot predict why more or less wolves are reproducing, dying, or moving around. Differences in the environment can affect wolf populations in unexpected ways, usually by influencing prey availability. Disease can also have an effect. Wolves tend to be well adapted to most diseases, but outbreaks of rabies and canine parvovirus have caused decreases in wolf populations. Census techniques and limitation
Counting wolves in a large area is difficult. In Denali's wolf program, scientists use aerial tracking methods to count every wolf in every pack for a complete population census. Usually, one or two wolves in each pack wear radio-collars, which help scientists to locate the packs. Once the packs are located, pilots and observers count how many wolves there are and what they are doing. Depending on where the wolves are, it can be hard to see and count all of the wolves, especially during the summer when vegetation can obscure resting wolves. Additionally, there are many reasons it can be difficult to maintain contact with the packs. Wolves die, move in and out of packs, form new packs, or split into multiple packs. Pilots and biologists search for tracks to find packs without collared members and obtain counts of those packs when possible. Snow conditions and weather often make locating new packs difficult until the spring months. To make things more challenging, wolves do not always travel and hunt together with their pack mates. During one aerial observation, a pilot might see three wolves traveling together with no other wolves in sight. The next day the very same pack members may be seen traveling as a group of seven. Counting wolves as they travel through thick timber can challenge even the most experienced observer. In addition, changes in weather, especially in early winter months, can make it difficult to see tracks and wolves. Studies tell us that wolf populations can handle an annual harvest of 28 to 50% of the population. However, this is a large range and not without controversy and on-going debate. For example, when wolves were greatly reduced due to wolf control the population rebounded quickly to density near that at the beginning of control. However, other evidence says that harvest of wolves may be harmful and cause population decreases. It is not clear what effect harvest has on the Denali wolf population. Many variables may have a role. Density dependent populations will have a better chance of bouncing back after mortalities. If a population is more isolated, fewer wolves will be migrating between populations to buffer mortalities. Finally, if harvest affects breeding members of the population, it may harm the chances of reproductive success. |
Last updated: August 22, 2022