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Yellowstone Wolf Project Annual Report 2019 · PDF file Yellowstone Wolf Project Annual Report Yellowstone National Park Yellowstone Wolf Project 2019 Wyoming, Montana, Idaho Yellowstone

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  • Yellowstone Wolf Project Annual Report

    Yellowstone National Park Yellowstone Wolf Project 2019 Wyoming, Montana, Idaho

    Yellowstone Center for Resources National Park Service

    Department of the Interior


  • 2 |Yellowstone Wolf Project Annual Report 2019

    Wolf-Prey Relationships Project staff detected 186 kills that were definitely, probably, or possibly made by wolves in 2019: 111 elk (59.7%), 38 bison (20.4%), 11 mule deer (5.9%), 2 deer of unknown species (1.1%), 3 coyotes (1.6%), 2 pronghorn (1.1%), 2 ravens (1.1%), one red fox (0.5%), one moose (0.5%), one golden eagle (0.5%), one bald eagle (0.5%), one mountain lion (0.5%), one domestic dog (0.5%), and 11 unidentified animals (5.9%). The domestic dog death was outside Yellowstone in a residential, gateway community and occurred at night. The composition of wolf-killed elk was: 31.5% calves, 7.2% yearlings, 21.6% adult females, 23.4% adult males, 7.2% adults of unknown sex, and 9.0% of unknown sex and age. The composition of wolf-killed bison was: 42.1% calves, 21.1% adult females, 28.9% adult males, and 7.9% of unknown sex and age. Wolf predation was monitored intensively for nearly five months of the year – one month in early winter (mid-November to mid-December), one month in late winter (March), and several months in the summer (May-late July). The type of prey killed by wolves varies by time period, but consists primarily of elk and bison.

    Winter Studies During the March 2019 late winter study period, air, ground, and GPS cluster search teams discovered 69 ungulate carcasses fed on by wolves. The GPS cluster crew searched 176 GPS clusters (locations in which a GPS-collared wolf spent ≥ 1hr) for two wolf packs (8 Mile and Junction Butte) through hiking or skiing over 930 kilometers (580 miles). Fifty-one (74.0%) of these ungulates were killed by wolves, including 29 (57.0%) elk, 9 (18.0%) bison, 10 (20.0%) deer, one (2.0%) moose, and 2 (4.0%) unknown species. Nine of the elk (31.0%) were calves, three (10.0%) were yearlings, four (14.0%) were adult females, nine (31.0%) were adult males, and four (14.0%) were adults of unknown sex. The wolves also fed on ten bison and eight elk that they did not kill.

    During the November-December 2019 early winter study period, we discovered 31 ungulate carcasses fed on by wolves. The GPS cluster crew hiked over 747 kilometers (465 miles)

    Summary There were at least 94 wolves in 8 packs (7 breeding pairs) living primarily in Yellowstone National Park (YNP) at the end of December 2019. Overall, wolf numbers have been relatively stable from 2009 to 2018 (80-108 wolves.) After dropping to 80 in 2018, numbers rebounded this year with high adult survival and several packs producing multiple litters. Seven breeding pairs (defined as an adult male and an adult female with at least two pups that survive through the end of the year) was the same as the average over the last decade. Pack size in 2019 ranged from 4 to 19, averaging 11.5 in size. Parkwide, 61 pups were produced and 42 survived (68.9%) to year end, with more in northern Yellowstone (27) than the interior (15) of the park. At the end of 2019, pups comprised 44.7% of the park population, higher than the average percentage (32.4%) over the last 10 years.

    while searching 71 GPS wolf clusters for the Junction Butte pack. Twenty-five (81.0%) of these ungulates were killed by wolves, which included 16 (64.0%) elk, 7 (28.0%) bison, one (4.0%) deer, and one (4.0%) unknown species. Three of the elk (19.0%) were calves, four (25.0%) were adult females, six (38.0%) were adult males, two (13.0%) were adults of unknown sex, and one (6.0%) was of unknown age and sex. The wolves also fed on four bison, one elk, and one deer that they did not kill.

    Summer Predation We also assessed wolf predation from May through late July by searching for prey remains at clusters (a location other than a home site where a wolf spent 30 minutes or more) generated from GPS collars. In 2019, we searched 147 clusters for wolf 907F of the Junction Butte pack. Crews hiked over 1,263 kilometers (785 miles) to detect 41 suspected kills or fresh carcasses of ungulate prey, which included 26 (63.0%) elk, 13 (32.0%) bison, and 2 (5.0%) unknown species.

    Mortalities Only two radio-collared wolves died in 2019. After being injured by other wolves, the dominant male of 8 Mile, 962M, could not keep up with the rest of the pack and became a lone wolf. He traveled out of Yellowstone and was harvested in Montana in January. Wolf 1118F’s GPS collar sent a mortality signal in September 2019, indicating she had not moved for at least four hours. We will attempt to recover the collar in summer 2020, but any remains will be scavenged or decomposed. In addition, staff recorded five uncollared wolf deaths. Two seven-month old pups from Junction Butte were hit by a vehicle in late November. Both pups died immediately. Three wolves were harvested in state hunting seasons: two Phantom Lake pups in Montana, and one Mollie’s wolf in Wyoming. For the second year in a row we recorded no intraspecific- caused mortality, which is usually the leading cause of natural mortality in the park. However, deaths of uncollared wolves from natural causes are rarely found and recorded.

    COVER: The Junction Butte pack takes time out to howl. NPS Photo - D. Stahler.

  • Yellowstone Wolf Project Annual Report 2019 | 3

    2019 Yellowstone Wolf Pack Territories (95% minimum convex polygons of aerial locations)

  • 4 |Yellowstone Wolf Project Annual Report 2019

    Disease There was no evidence of any major disease mortality in 2019. The wolf density in northern Yellowstone is the highest it has been in over 10 years (approximately 50-70 wolves/1000km2, depending on movements of the Wapiti Lake and Mollie’s packs), which may facilitate disease transmission over the next year. Ellen Brandell, a graduate student at Penn State, is investigating the prevalence and abundance of canine parasites and has collected scat samples from most packs in northern Yellowstone.

    Reproduction Each year staff attempt to establish early pup counts at dens by either observing from the ground through spotting scopes or, more often, taking photos of the den area during tracking flights. Since wolf pups normally stay underground for their first three to five weeks, the earliest counts for each pack are often of two to three month old pups. For some packs whose den sites are unknown or hidden, we do not get pup counts until the pups are moved to a rendezvous site in the early fall. This year the Wolf Project documented at least 61 pups born to seven different packs. Four packs produced multiple litters: Junction Butte (17 pups from four litters), 8 Mile (11 pups from two litters), Phantom Lake (at least 13 pups from at least three litters), and Wapiti Lake (9 pups from two lit- ters). Many of these packs, however, lost some pups by the end of the year and pup survival for those packs with mul- tiple litters was 64.0%. Of the minimum 61 pups produced in all packs, 42 (68.9%) pups survived to the end of the year.

    Wolves often travel single file when in snow - unless of course, you are a pup (first wolf in line and flanking white female.) Wapiti Lake pack in Hayden Valley

    in late 2019. NPS photo - D. Smith.

    Wolf Capture Twenty-four wolves from six packs were captured and col- lared in 2019. Six of these replaced old or malfunctioned transmitters. A number of measurements and biological samples were also taken while the wolf was sedated. Twelve females and twelve males were captured; three were old adults (≥6 years old), six were adults (2-5 years old), three were yearlings, and twelve were pups. A female from the Cougar Creek pack was collared and her genetic markers in- dicate she is actually 953F from Cougar Creek, whose collar was chewed off in 2017.

    Wolf Management and Outreach Wolf management activities included den site closures and several hazing events. Staff continued to manage wolf viewing areas in Slough Creek, Lamar Valley, and other areas where wolves were frequently observed. Wolf Project staff observe wolves through spotting scopes and, during 2019, at an average distance of 2.4 km. This distance facilitates data collection on completely natural wolf behavior uninfluenced by human presence. In January, biological technician Jeremy SunderRaj spotted the Junction Butte pack from a distance of 11.4 km (over 7 miles) away! Hayden Valley, a common place to view wolves in the past, was rarely used by the Wapiti Lake pack in 2019. Public outreach included giving 119 formal talks (six at scientific conferences), 76 interviews, educating at least 10,000 people while viewing wolves, making at least 15,000 visitor contacts, and giving 158 informal talks in the field.

  • Yellowstone Wolf Project Annual Report 2019 | 5

    Wolf #/Sex Date of

    Capture Age Color Pack

    1104F 2/19/2019 Yearling Black Wapiti Lake

    1198F 2/19/2019 Pup Black Cougar Creek

    1199F 2/19/2019 Pup Black Cougar Creek

    1200M 2/19/2019 Adult Black Cougar Creek

    1201F 2/19/2019 Pup Black Wapiti Lake

    1203F 2/21/2019 Yearling Gray Wapiti Lake

    1117M 2/22/2019 Adult Black Cougar Creek

    1204F/953F 2/22/2019 Adult Gray Cougar Creek

    1047M 12/14/2019 Adult Black Junction Butte

    1048M 12/14/2019 Adult Black Junction Butte

    1228F 12/14/2019 Pup Gray Junction Butte

    1229F 12/14/2019 Pup Black Junction Butte

    907F 12/14/2019 Adult Gray Junction Butte

    1230M 12/15/2019 Pup Black 8 Mile

    1231M 12/15/2019 Pup Gray 8