Eleven Years with Wolves - What We've Learned
Tuesday, April 25, 2006 - 12:00 AM MDT
By Jim Lukens, Salmon Region Supervisor, IDFG Of all wild animals, wolves generate more emotions among people than any other species. Both folklore and human nature play into fearful emotions through legends such as werewolves, stories like Little Red Riding Hood, and our tendency to hate what we fear or do not understand. On the flip side, native cultures in North America and elsewhere credit wolves with almost mythical power. In reality, neither representation is true. Wolves are predatory animals, just like any other. In 1995, wolves were reintroduced in Idaho and have been intensively observed ever since. During that time we have learned a great deal about these animals, enough to be able to clear up some misunderstandings. Distribution, Number and Ancestry Any discussion of numbers must be prefaced by the fact that these are estimates. Wolves in Idaho continue to pioneer new territories with little known about wolves in wilderness areas. By the end of 2005, Idaho had 59 documented resident wolf packs with a total population estimate of 512 wolves. Additionally, 11 documented border packs have established territories along state boundaries between Idaho, Montana, and Wyoming. Forty packs produced an estimated 123 pups. In 2005, the Salmon Region had 13 documented resident, three documented border, and one suspected border packs. Nine packs reproduced and qualified as breeding pairs while the reproductive status of the remaining four resident packs was undetermined. Idaho's wolves are often incorrectly called "Canadian" wolves. The U.S. Fish and Wildlife Service only recognizes the gray wolf (Canis lupus) for recovery purposes. In the book, Wolves: Behavior, Ecology and Conservation, edited by L. David Mech and Luigi Boitoni, Ronald M. Nowak provides evidence for two subspecies of wolves inhabiting the central and western portions of the United States, both of which moved freely across the Canadian border. Other taxonomists reject the subspecies theory, believing that the same wolf species lived in both the western U.S. and Canada. When selecting wolves for release into Idaho, biologists selected populations in Canada that were already utilizing elk prey and were living in habitat similar to that of Idaho. This increased the suitability of these wolves for life in Idaho. Some people say that wolves used to be smaller than the reintroduced ones, but little evidence supports this claim. However, animal body size tends to increase at the northern parts of their range and is related to staying warm. Wolf Predation While a fair amount of information regarding prey selection and non-winter food habits has been collected in places like Yellowstone, little information has been collected in Idaho. While it is often tempting to generalize, wolf predation data from one area does not necessarily represent predation characteristics from another. The same is true for data collected from one season being applied to another season. Factors like variations in wolf densities; interactions with other predators; number, distribution and species of prey; weather; and availability of alternate prey species prevent comparison. Despite this variation, one generalization that tends to hold true for most wolf-prey systems is the tendency for wolves to select prey that are disadvantaged such as the young, the old, the sick or injured, or weak individuals. These animals often fall to the rear of a herd where they become vulnerable to pursuing wolves. Jason Husseman, Salmon Region wolf biologist, conducted a winter wolf and mountain lion predation study in Unit 28 from 1999 - 2001 for his Master's thesis. During that period, Husseman examined 120 wolf kills, comprised of elk (77%) and deer (23%). Wolves selected for elk calves (60%) but also killed cows (32%) and bulls (8%). Deer taken by wolves were mostly fawns (65%). The average age of adult elk killed by wolves was 12.6 years, significantly older than a sample of 31 cow elk (7.3 years) killed by hunters in the same unit. Husseman also determined that each wolf pack in his study area made a kill every 2 - 3 days. As mentioned above, this information cannot be generalized to other wolf packs in Idaho. In addition, observations from around the state show that kill rates declined once prey species adapted to the presence of wolves Wolves are often accused of killing for "fun" and wasting game. In his study, Husseman also examined carcass utilization and found that 80 percent of carcasses were more than three-fourths utilized and all kills were fed upon. While "surplus killing," the killing of more prey than can be consumed, has been documented, these incidents usually occur under unusual circumstances such as extremely deep snow conditions that severely disadvantage prey. Furthermore, wolves usually return later to consume the "leftovers." Another interesting aspect of Husseman's work involved examining the health of each prey animal when killed by wolves or lions. Overall, the condition of wolf-killed elk was consistently poorer than that of elk taken by mountain lions. This was determined by measuring bone marrow fat content. Bone marrow fat is the last body fat reserve available to deer and elk during winter, indicating the level of malnutrition. Research has shown that when animals fall below a certain level of bone marrow fat content, they die. Husseman determined that 25 percent of the animals killed by wolves would have died of malnutrition anyway. This is supported by results from a long-term study of mule deer fawn survival across the state. Radio collared fawns are tracked and the causes of mortality determined. Of 285 deer fawns tracked by Salmon Region biologists, 141 died. Seventy-two fawns died directly of malnutrition while predation was the cause of death for 69 (24 percent) of the fawns. Predators included coyotes (44), mountain lions (9), wolves (7), bobcats (4) and unidentified predators (5). Status of Big Game Herds Wolves prey upon deer and elk as do other predators, but what has been the impact to our game herds? At the time wolves were released into Idaho, the elk herd in the Salmon Region numbered approximately 28,000 animals. The current estimate gained by aerial surveys and hunter harvest information is approximately 25,000. While this estimate is lower, it is important to note several facts: the estimate still exceeds the Elk Plan objective by about 1,000 animals; all elk zones in the Region have generally been meeting plan objectives; and some high population units have deliberately been reduced through cow harvest to reach objectives. In addition, data gathered from a new radio collaring study initiated in 2005 shows 85 percent deer survival and 82 percent elk survival in the Salmon Region and Units 50 and 60A in the Upper Snake Region. Biologists consider 80 percent doe survival and 85 percent cow elk survival normal and sustainable. Elk mortality factors included hunter harvest (52 percent), mountain lions (30 percent), wolves (7 percent), malnutrition (7percent), and unknown predation (4percent). Deer mortality resulted from lions (32 percent), hunter harvest (18 percent), accidents (14 percent), unknown causes (14 percent), wolves (9 percent), roadkill (9 percent), and malnutrition (4 percent). In addition, deer numbers are limited in the region by habitat condition and weather both of which can significantly impact deer populations. Livestock Depredations Although not considered a normal prey item, wolves occasionally kill domestic livestock. A compensation fund was set up by Defenders of Wildlife for both documented wolf-caused losses and probable losses. From 1996 to 2005, Defenders has paid $135,933 to compensate statewide losses. Here in the Salmon Region, payments have totaled $42,013 for 22 sheep, two guard/herding dogs and 75 cattle. Documented loses not covered by Defenders or other funds are compensated by the Idaho Wolf Depredation Compensation Fund which was established as part of the Idaho Wolf Depredation Compensation Plan This fund uses federal monies to compensate producers for losses above documented historical levels and has averaged about $100,000 per year for the last three years. Wolf depredations are managed by Wildlife Services (WS), a branch of the U.S. Department of Agriculture. When a livestock depredation is reported, IDFG contacts WS and they attempt to reduce further depredations by controlling offending animals using either lethal or nonlethal measures. The 10(j) rule implemented in 2005 gives producers more flexibility for controlling wolves attacking, harassing, or injuring domestic livestock and dogs. Threat to Humans Recently reported human/wolf encounters have raised concerns regarding threat to human life. All wild animals can be dangerous to humans. Two behavioral changes affect animals and their likelihood of injuring humans. Wild animals that continually come into contact with humans can become "habituated," losing their natural fear. This often occurs when the animal associates people with food and this can cause an animal to become aggressive toward humans. Habituation is thought to be the cause of the first probable human fatality attributed to wolves in North America since 1900. This fatality occurred in November, 2005 in northern Saskatchewan. Subsequent investigation by Paul Paquet, a University of Calgary wolf biologist and provincial authorities has determined that some wolves in the area had been attracted to a garbage dump; had possibly been fed and regularly photographed at a nearby mining camp, causing the animals to become habituated. Like your dog, wolves are curious animals, readily investigating something new in their environment. And the vast majority of wolf-human encounters are simple curiosity on the part of the wolf. Wolves are, however, very territorial and intolerant of the presence of another canine. Hikers with dogs have occasionally been followed, barked at, and growled at by resident wolves protecting their territory from a trespassing canine. Wolves have also been documented exhibiting these same behaviors when pups are present. A person in wolf country has a greater chance of being hit by lightning, dying of a bee sting or being killed in a vehicle collision with a deer than being injured by a wolf. Current and Future Management Although wolves are still protected under the Endangered Species Act, the Idaho Department of Fish and Game has assumed some wolf management authority under the 10(j) rule. As provided under this rule, Idaho now has a memorandum of agreement allowing Idaho to manage wolf populations in the state. Once the wolf is delisted, IDFG will assume full management responsibility with direction from the Idaho Wolf Conservation and Management Plan. The goal of this conservation and management plan is to ensure the long-term survival of wolves in Idaho while minimizing wolf-human conflicts. The management goal is to maintain more than 15 wolf packs statewide. In 2005, the Fish and Game Commission classified the wolf as a big game animal under authorization provided by the Plan, but wolves cannot be managed as such until they are delisted. For delisting to occur, Idaho, Montana, and Wyoming must have approved management plans in place. Thus far, Wyoming does not have such a plan and until it does, the delisting process cannot continue. Once delisting occurs, IDFG looks forward to being able to manage wolves as it does other big game species.