• Range Writing

Wolf News: 35-member pack

The Wyoming Game & Fish Department’s annual report on wolf monitoring and management covers activities and information for 2020.


From the executive summary:

• At the end of 2020, the gray wolf population in Wyoming remained above minimum delisting criteria, making 2020 the 19th consecutive year Wyoming has exceeded the numerical, distributional, and temporal delisting criteria established by the U.S. Fish and Wildlife Service.

• At least 327 wolves in ≥44 packs (including ≥22 breeding pairs) inhabited Wyoming statewide on December 31, 2020.


Area Minimum # # Packs #Breeding Pairs

Trophy zone 147 24 11

Yellowstone 123 9 7

Reservation 21 3 2

Predator zone 36 8 2



• A total of 119 wolf mortalities were documented statewide in Wyoming in 2020: 71 in the trophy zone, 43 in areas where wolves are primarily designated as predatory animals, 4 in Yellowstone National Park, and 1 in the Wind River Reservation. Causes of mortality included: human-caused = 104 (87% of mortalities); natural = 11 (9%); and unknown = 4 (4%). Forty-three wolves were captured and radio-collared for monitoring and research in 2020.


• Natural mortalities documented in Wyoming included 3 wolves killed by other wolves and 1 wolf killed in an avalanche.


• At the end of 2020, there were at least 36 wolves, including 8 packs, and 2 breeding pairs in the predatory animal areas in Wyoming.


Disease monitoring

“While evidence for mange and distemper has been present in the wolf population in Wyoming, they have had little impact on wolf population dynamics outside Yellowstone National Park. Management actions such as hunting and conflict control in the Wolf Trophy Game Management Area (WTGMA) appears to have held the population below the threshold where disease outbreak would be more likely, however, the WTGMA wolf population increased rapidly following the reinstatement of Endangered Species Act protections in 2014 and remained at relatively high density from 2015 through early 2018. This increase in population density in WTGMA was correlated with an increase in detection of mange and distemper in the wolf population through 2018. Documentation of disease in the WTGMA wolf population was markedly reduced during 2019 and 2020 as the population was managed at lower density.”


“As expected, documentation of mange continued to remain low in the WTGMA in 2020. The Game Creek pack continued to use the same territory and homesites used formerly by the Horse Creek pack, which was mostly killed by mange in 2018, and showed signs of significant mange infection in winter 2019/20 and 2020/21. The Department will continue to monitor mange in wolves and how it correlates with reduced wolf density.”


“The proportion of wolves captured during winter that tested positive for distemper infection increased from 2015 through 2018 and was correlated with increasing wolf population density in the WTGMA. The proportion of wolves that tested positive during winter capture in 2020 (November 2020-March 2021) continued to decrease from a high in 2018 following population peaks after wolves were relisted in 2014 through early 2017. Decreasing prevalence of distemper has been correlated with a reduction in wolf population density in the WTGMA from 2018-2020. There were no documented wolf mortalities caused by distemper during 2020.”


“The U.S. Fish and Wildlife Service and Yellowstone National Park have surveyed for evidence of canine parvovirus while managing Wyoming wolf populations and found a high rate of infection (>80% of wolves exposed) with no apparent deleterious effects to individual wolves or the population. The Wyoming Game and Fish Department has not tested samples for canine parvovirus to date, but continues to retain samples from all captured wolves that could be tested for canine parvovirus or other diseases if the need arises in the future.”

Yellowstone National Park

At the end of 2020, Yellowstone National Park had at least 123 wolves in nine packs. According to the report:

“This census was the highest since 2008 (124 wolves) and marked a one-year increase of 31% after a decade of very little population change year-to-year. Much of the growth was attributed to successful pup production and survival in multiple packs, most notably the Junction Butte pack which produced 4 litters and raised 18 pups through the end of the year.


“The number of packs and breeding pairs was the same as the average over the last decade. Pack size in 2020 ranged from 4 to 35, averaging 13 in size. This average was higher than the long- term average pack size of 9 to 10. Again, this average was largely driven by the exceptional size of the Junction Butte pack at 35 members. Average pack size not including Junction Butte was 11. Two other packs, 8 Mile and Wapiti Lake, had 21 and 20 members, respectively, making 2020 the only year with 3 packs of 20 or more members in mid-winter. The only year with 2 packs that large was 2000 when the Druid Peak pack had 27 and Nez Perce pack had 22 members. Every other year’s official count has had no packs (15 years) or 1 pack (8 years) with at least 20 members.”


• Four wolves died in Yellowstone National Park in 2020, including 3 wolves killed by other wolves and 1 wolf that died of a severe abdominal infection of unknown cause.


• “By late December several members of the Junction Butte pack showed signs of hair thinning and loss, which may be an early indication of mange infection. We will continue to monitor the changes in infection at the individual, pack, and population levels. Wolf density in northern Yellowstone National Park is consistently higher than most other places wolves live. The abundance and density of predator species in the Greater Yellowstone Ecosystem leaves open the possibility of diseases such as canine distemper virus to occasionally cycle through. The last documented outbreak of canine distemper virus in wolves in Yellowstone National Park was 2017.”


Wolf Hunting

In 2020, the Wyoming Game and Fish Department implemented a wolf hunting season with the biological objective to stabilize the wolf population at approximately 160 wolves in the WTGMA. A mortality limit of 51 wolves was divided between 13 hunt areas in the WTGMA and 1 hunt area in the Seasonal WTGMA (hunt area 12).


• A total of 31 wolves were killed during the wolf hunting season in 2020.


• A total of 2,221 wolf hunting licenses were sold to 2,077 individuals (1,848 residents and 229 nonresidents) for the 2020 wolf hunting season, more than in 2019 (1,885 licenses) and slightly below hunting seasons in 2017-2018 (average of 2,590 licenses).


• Slightly more females than males (17 females:14 males) and nearly twice as many black than gray colored wolves were taken in the hunt (11gray:20 black). Wolves taken during the hunting season in 2020 were primarily adults and subadults (4 juveniles:14 subadults:13 adults).


Livestock Depredations

Wolves were confirmed to have killed or injured 76 head of livestock (54 cattle, 12 sheep, and 10 chickens) and 1 dog statewide in Wyoming in 2020. Fourteen packs were involved in ≥1 livestock conflict statewide. Forty-three wolves were lethally and legally removed by agencies or the public in an effort to reduce livestock losses to wolves (27 in the WTGMA, 16 in predatory animal areas in WYO).


• “In 2020, the Wyoming Game and Fish Department paid $152,860 to compensate 20 livestock producers for livestock killed or injured by wolves in the WTGMA and Seasonal WTGMA. Compensation payments declined from >$300,000 from 2014-2017 to <$170,000 from 2018-2020, mirroring synchronous declines in conflict between wolves and livestock following removal of Endangered Species Act protections in 2017. Compensation payments have consistently remained lower under Wyoming Game and Fish Department management from 2018-2020.”



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