Wolf numbers drop – but less than expected


SUBLETTE COUNTY – Overall – and by design –­ Wyoming’s gray wolf population declined in 2018 by 18 percent, from 347 within the state’s boundaries in 2017 to 286 at the end of 2018.

Those 286 wolves live in about 46 packs with at least 20 breeding pairs; recovery criteria for all of Wyoming require a total of at least 150 wolves and at least 15 breeding pairs.

The stated goal of Wyoming Game and Fish is to manage for 160 gray wolves in the trophy-game area outside Yellowstone National Park and the Wind River Reservation, according to the 2018 Wyoming Gray Wolf Monitoring and Management Report.

Pinedale Game and Fish wolf biologist Ken Mills coordinated the annual report.

“Those numbers were reduced,” Mills said last week. “At 152 wolves in the trophy-game area, we were very close to our objective.”

This the 17th year that gray wolves, reintroduced in Yellowstone in 1995, are above and beyond the federal required numbers for recovery.

 

Recovery

In Wyoming, wolf management is divided among Yellowstone, the Wind River Indian Reservation, Grand Teton National Park and National Elk Refuge together, and then the state’s trophy-game area. Outside those areas, wolves are categorized as predators and not managed by state or federal agencies, although hunters must report their kills.

At the end of 2017 in the Game and Fish trophy-game area, GTNP and the National Elk Refuge – shortened to WYO – there were about 238 wolves in 35 packs with 19 breeding pairs. This came after Game and Fish had predicted about 24-percent mortality.

The WYO population dropped 18 percent at the end of 2018 to 196 wolves, 35 packs and 13 breeding pairs. Mills said some breeding pairs denned but never had pups; another observation was that there were fewer pups per breeding pair and pack at the end of last year. Overcrowding and canine diseases affected reproduction.

GTNP and refuge numbers are added to the WYO count, with the requirements of at least 100 wolves and 10 breeding pairs. Yellowstone and the reservation must count at least 50 wolves and five breeding pairs.

 

Control factors

Hunting seasons as well as lethal removals after human and livestock conflicts are part of the state’s management plan.

Last year, Wyoming set a hunting quota of 58 trophy-game wolves and only 43 were taken, 39 legally. The trophy-game hunt quota is one element to control gray wolf numbers, where the wildlife agency’s forecast for 2018 predicted a potential decline of almost 50 percent.

“Total wolf mortality limits were set to reduce the Wyoming Trophy-Game Management Area wolf population from an estimated 210 wolves at the start of 2018 to approximately 160 wolves at the end of 2018,” it says.

“(Game and Fish) predicted the population would be reduced in the WTGMA from at least 210 wolves at the beginning of 2018 to about 160 wolves at the end of 2018 if 49.5 percent of the wolves present in 2018 died from all human-caused mortality,” it explains. “The average non-hunting human-caused mortality rate (average) of 22.8 percent was then subtracted from 49.5 percent to obtain a 26.7 wolf hunting mortality rate, which equaled … 56 wolves.”

The 56-wolf quota was divided among the trophy-game hunt areas, which opened in September last year to coincide with other big-game hunts.

Hunting quotas complement the “predicted non-hunting human causes” and other factors such as wolves killing wolves, other animals killing wolves, diseases and unknown.

“Evaluation of the 2018 hunting season data confirmed the hunting strategy in 2018 reduced the population as intended,” the report says. “The wolf population demonstrated a lower resilience to human-caused mortality in 2018 than predicted (due to) density-dependent factors” in the population.

While wolves were listed as “endangered,” numbers grew through 2017 when they were again delisted and hunted. Packs and individuals moving into already-claimed territory create these “density-dependent factors” that are expected to increase mortality and lower reproduction. Seven packs denned with no pups spotted, the report says. One pack had pups last year but they were gone by year’s end, possibly from distemper, Mills said.

In 2018, 177 dead wolves were confirmed including three in Yellowstone and two for livestock conflicts on the Wind River Reservation. Ninety-percent of the deaths were human-caused, 9 percent natural and 1 percent “unknown.”

Breaking those down more for the WYO area, hunting removed 39 wolves. Lethal control by Game and Fish and USDA Wildlife Services took out 64 more for livestock predation and predator zone hunters killed 42. Fourteen died of natural causes (higher than past years), 11 from other human causes, two “unknown,” 14 were dispersed and four were missing.

Hunter harvests were divided fairly evenly from September through December with 23 females and 20 males, 24 gray and 19 black, and 19 adults, 12 yearlings and 12 juveniles reported taken.

“The higher proportion of adults taken in 2018 compared to previous hunting seasons was likely a function of reduced availability of juvenile wolves during the hunting season, a result of reduced production and survival of pups in 2018 compared to previous years.”

In the predator area, of the 42 wolves reported taken, 29 were by rifle, 12 with traps and one by another method. Reports showed 23 females and 19 males, 21 gray and 14 black (seven not reported), with 13 adults, 19 subadults, four pups and five with age not reported.

As for confirmed livestock kills, the numbers dropped dramatically – almost by half in 2018 at 70 – but more wolves were taken in control actions than in 2017. In 2017, WYO wolves killed 110 cattle, 81 sheep and one dog, and 61 wolves were removed. In 2018, wolves killed 54 cattle, 15 sheep and one horse, and 64 wolves were removed.

Of confirmed livestock kills, 52 percent were on public land and 48 percent on private land, with more cattle targeted on private land and sheep on public land. No conflicts were documented on Game and Fish elk feedgrounds.

The future goal of Game and Fish, as the population settles, is to keep the wolf numbers killed just above the number of livestock killed, Mills said last week.

Ranchers were compensated $169,107 in 2018, “significantly lower following four years of high wolf density and associated livestock damages,” after 2016 and 2017 compensation rose above $350,000.

Of the 64 wolf kills, 52 were by agencies, 10 with lethal-take permits and two in defense of private property. Thirty-nine were in the trophy-game zone and “a minimum” of 25 in the predator area.

Another big step for research was capturing more wolves and attaching VHF and GPS collars to monitor their movements and territories. Game and Fish crews continued aerial captures into this year and as of March 31, have collars on 83 wolves in 31 packs and two loners.

To see the 2018 Wyoming Gray Wolf Monitoring and Management Report or previous years, go to https://wgfd.wyo.gov/wildlife-in-wyoming/more-wildlife/large-carnivore/wolves-in-wyoming.

 

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