Lendrum P.E.,Panthera |
Elbroch L.M.,Panthera |
Quigley H.,Panthera |
Thompson D.J.,Wyoming Game and Fish |
And 2 more authors.
Journal of Zoology | Year: 2014
Cougars Puma concolor are described as 'habitat generalists', but little is known about which ecological factors drive their home range selection. For example, how do resource distributions and inter-species competition with dominant competitors (i.e. wolves, Canis lupus) over such resources, influence the distributions of cougars on the landscape? We tracked cougars using Very High Frequency (VHF; 2001 to 2005) and GlobalPositioningSystem (GPS; 2006 to 2011) technology in the Southern Yellowstone Ecosystem (SYE) in northwestern Wyoming, USA. We tested whether data type (VHF vs. GPS), cougar sex, access to forests (refugia) or hunt opportunity explained the size of 50% and 95% kernel density estimator (KDE) home ranges. Second, we quantified attributes of cougar home ranges and tested whether they were different from attributes of the overall study area, to address the ecological question: Do cougars select home ranges based on the availability of refugia, hunt opportunity or some combination of the two? Cougar sex and data type proved significant predictors of home range size for both 95% and 50% KDEs, and the amount of forest partly explained the size of 50% KDEs. Cougar home ranges derived from VHF data were 1.4-1.9 times larger than home ranges derived from GPS data; however, home range attributes determined from VHF and GPS data were remarkably equivalent. Female cougars selected home ranges with higher hunt opportunity than males, supporting the assumption that females primarily select home ranges with suitable prey to sustain themselves and their young. All cougars selected home ranges further from known wolf packs, providing evidence for newly established competition between resident cougars and recolonizing wolves, but did not select home ranges with greater access to landscape refugia. Our results provided evidence that cougars in the SYE select home ranges that provide high hunting opportunity and a spatial buffer that mitigates potential conflicts with a dominant competitor. © 2014 The Zoological Society of London.
Fremgen A.L.,University of Missouri |
Hansen C.P.,University of Missouri |
Rumble M.A.,Rocky Research |
Gamo R.S.,Wyoming Game and Fish |
Millspaugh J.J.,University of Missouri
Journal of Wildlife Management | Year: 2016
It is unlikely all male sage-grouse are detected during lek counts, which could complicate the use of lek counts as an index to population abundance. Understanding factors that influence detection probabilities will allow managers to more accurately estimate the number of males present on leks. We fitted 410 males with global positioning system and very high frequency transmitters, and uniquely identifiable leg-bands over 4 years in Carbon County, Wyoming. We counted male sage-grouse using commonly used lek-count protocols and evaluated variables associated with our ability to detect marked males using sightability surveys on 22 leks. We evaluated detection probabilities of male sage-grouse based on factors related to bird characteristics such as age or posture, lek and group size, lek characteristics such as vegetation cover or aspect, light conditions, weather, and observer. We then applied the detection probabilities to more accurately estimate male counts on leks. Detection probabilities were generally high (x¯ = 0.87) but varied among leks from 0.77 to 0.93. Male sage-grouse detection declined with increasing sagebrush height and bare ground and increased with more snow cover. Detection probabilities were also lower when observers counted from a higher elevation than the lek. Our sightability models predicted detection well and can be used to accurately estimate male abundance on leks from lek counts, which is especially useful where accurate abundance estimates are required or inference about population status is based on only 1 count. Further, it is important to consider lek attendance as a component of counts on leks because it affects availability of male sage-grouse for detection during lek counts. Detection can be maximized by conducting lek counts from 30 minutes before sunrise to 30 minutes after sunrise, although current protocols recommend lek counts can be performed up to 1 hour after sunrise. Detection can also be maximized by conducting lek counts ≥2 days after snowfall, which maximizes attendance and detection. © 2015 The Wildlife Society.
Mark Elbroch L.,Panthera |
Lendrum P.E.,Panthera |
Newby J.,Craighead Beringia South |
Quigley H.,Panthera |
Thompson D.J.,Wyoming Game and Fish
Zoological Studies | Year: 2015
Background: Niche differentiation may betray current, ongoing competition between two sympatric species or reflect evolutionary responses to historic competition that drove species apart. The best opportunity to test whether ongoing competition contributes to niche differentiation is to test for behavioral shifts by the subordinate competitor in controlled experiments in which the abundance of the dominant competitor is manipulated. Because these circumstances are difficult to coordinate in natural settings for wide-ranging species, researchers seize opportunities presented by species reintroductions. We tested for new competition between reintroduced wolves and resident cougars in the Southern Yellowstone Ecosystem to assess whether wolves might be impacting the realized niche of sympatric cougars. Results: Between 2002 and 2012, a period during which wolves increased from 15 to as high as 91 in the study area, cougars significantly increased the percentage of deer and decreased the percentage of elk in their diet in summer. Our top models explaining these changes identified elk availability, defined as the number of elk per wolf each year, as the strongest predictor of changing cougar prey selection. Both elk and deer were simultaneously declining in the system, though deer more quickly than elk, and wolf numbers increased exponentially during the same time frame. Therefore, we concluded that prey availability did not explain prey switching and that competition with wolves at least partially explained cougar prey switching from elk to deer. We also recorded 5 marked cougar kittens killed by wolves and 2 more that were killed by an undetermined predator. In addition, between 2005 and 2012, 9 adult cougars and 10 cougar kittens died of starvation, which may also be in part explained by competition with wolves. Conclusions: Direct interspecific predation and shifting cougar prey selection as wolves increased in the system provided evidence for competition between recolonizing wolves and resident cougars. Through competition, recolonizing wolves have impacted the realized niche of resident cougars in the Southern Yellowstone Ecosystem (SYE), and current resident cougars may now exhibit a realized niche more reflective of an era when these species were previously sympatric in the Yellowstone Ecosystem. © 2015 Elbroch et al.
News Article | March 26, 2016
A wolf pack killed a total of 19 elk in a suspected "surplus killing" in Wyoming. The Wyoming Game and Fish Department has confirmed the tragic incident after it performed its investigation on site. The Details Of The 'Surplus Killing' The remains of the elk were found on Thursday morning at one of the department's feeding areas, near Bondurant, which is a community located at the southeast portion of Jackson. "We went and investigated it and it turned out to be a total of 19 that we found and documented," says regional wildlife supervisor John Lund. He adds that out of the 19 carcasses, 17 were calves and the remaining two were adult cows. Lund explains that a number of wolves arrived during the night and killed the elk. Authorities are stunned by the recent incident because such surplus killing is considered highly rare. U.S. Fish and Wildlife Service's Mike Jimenez says wolves, unlike humans, do not consider killing as a sports activity. In fact, he was part of a team who conducted an eight year research that investigated elk feeding grounds. In general, wolves do not slay something that it would not eat. Lund attests to the rarity of the surplus killing by saying that one or two elf killings per night is quite common and is not really much of a big deal, but seeing 19 carcasses just after one night is fairly uncommon. The good thing about the situation is that authorities know which wolf pack was responsible for the killings. Lund says it is the pack that has been hitting the same feeding ground. As far as the team can tell, it is the so-called Rim Pack, which had about nine wolves. Unfortunately, the Wyoming Game and Fish Department does not have the authority to follow up the surplus killing. This is because only the U.S. Fish and Wildlife Service has the jurisdiction to enact on the problem. While the department is responsible for the management and supervision of the feeding grounds, the wolves are outside the scope of their responsibility.
The region's grizzlies have federal protections, but that could change in coming months, turning control over to the states. The AP obtained a draft agreement detailing the states' plans for the animals. The deal puts no limits on grizzly bear hunting outside a 19,300-square-mile management zone centered on Yellowstone National Park. Inside the zone, which includes wilderness and forest lands near the park, hunters in Wyoming would get a 58 percent share of the harvest, a reflection that it's home to the bulk of the region's bears. Montana would get 34 percent, and Idaho, 8 percent. The management zone has an estimated 717 grizzly bears. There is no estimate of how many live outside the area, although the number is increasing as they expand into new habitat, biologists say. Wildlife advocates say the bear population remains too small to withstand much hunting. That's a particular concern given the large numbers of bears already dying, including during surprise run-ins with hunters and after livestock attacks that prompt officials to trap and kill problem bears. In 2015, at least 59 Yellowstone-area grizzlies were believed to have been killed or trapped and removed by government agencies. That's the most since the animal received protection under the Endangered Species Act in 1975. Despite the deaths, state officials say the grizzly population has recovered from excessive hunting and trapping that exterminated grizzlies across most of the U.S. in the early 1900s. The officials have increased pressure on U.S. Fish and Wildlife Director Dan Ashe in recent months to revoke the animal's threatened status. Directors of the three states' wildlife agencies told Ashe in a Dec. 4 letter that such a step was long overdue. "It is critically important that we capitalize on our tremendous progress and momentum ... by proceeding with a long overdue delisting" of bears from the threatened species list, the directors wrote. It was signed by Idaho Fish and Game Director Virgil Moore; Montana Fish, Wildlife and Parks Director Jeff Hagener; and Wyoming Game and Fish Director Scott Talbott. Montana wildlife activist Louisa Wilcox says the states' push for hunting ignores the many bears already dying of other causes. "You're not even hunting them, and you have this ongoing pileup of dead bears," Wilcox said. "Adding a hunt will drive down the population. It's exactly the wrong thing to do." Legal hunting of Yellowstone-area grizzlies last occurred in the 1970s. At least 58 bears were killed in Montana and Idaho in the five years leading up to a prohibition on hunting in 1975. Historical harvest figures for Idaho were not available. Any future hunts would be conservative and need approval from wildlife commissioners following a public comment period, said Quentin Kujala, chief of wildlife management for Montana Fish Wildlife and Parks. The size of each harvest would be on a sliding scale, with the intention of keeping the bear population viable and avoiding the need to reinstate federal protections, Kujala said. More hunting would be possible when the population tops 675 bears, and hunting would be largely barred if the number falls below 600. "We're definitely not talking about a large number. We're not talking hundreds or anywhere near that," Wyoming Game and Fish spokesman Renny MacKay said. A decision on whether protections should be lifted is due early this year, according to the U.S. Fish and Wildlife Service. Barring a successful court challenge, it would take approximately a year for such a rule to go into effect. The pending agreement between the states is not required for federal protections to be lifted, state officials said. Explore further: Grizzly bears still need protecting, US court rules