Research on the Relationship between Mountain Lions and Deer
... Whether hunters killed 10 percent or 35 percent of cougars, the population remained the same... Based on the the 13-year study, the Washington Department of Fish and Wildlife is implementing a new cougar management plan based on equilibrium management. Hunters will remove no more than the surplus of animals that would be generated through natural reproduction ... the 13-year study headed by Rob Wielgus, director of WSU’s Large Carnivore Conservation Lab ...
Effects of male targeted harvest regimes on prey switching by female mountain lions: Implications for apparent competition on declining secondary prey JR Keehner, RB Wielgus, AM Keehner - Biological Conservation, 2015
... Harvest regimes which target male carnivores are now widely accepted to result in increased sexually selected infanticide (SSI) because of rapid male turnover and immigration by non-sire males, and sexually segregated habitat use because of female avoidance of infanticidal males ... only females with cubs selected for declining mule deer at high elevations and only during summer, when kittens were vulnerable to infanticide — other sex and reproductive classes selected for abundant increasing white-tailed deer at low elevations. We suggest that harvest regimes which focus on male harvest to reduce predation on declining secondary prey could be causing increased predation on declining secondary prey elsewhere.
Ecologists wondering where the lions, and other top predators, are September 3, 2015 Science Daily
... New law of nature: more crowding leads to fewer offspring ... Physiologists have long known that the speed of growth declines with size ... in the lushest ecosystems, no matter where they are in the world, the ratio of predators to their prey is greatly reduced. This is because with greater crowding, prey species have fewer offspring for every individual...
The predator-prey power law: Biomass scaling across terrestrial and aquatic biomes September 4, 2015, Science, Ian A. Hatton, Kevin S. McCann, John M. Fryxell, T. Jonathan Davies, Matteo Smerlak, Anthony R. E. Sinclair, Michel Loreau
... . We show a robust scaling law that emerges uniquely at the level of whole ecosystems and is conserved across terrestrial and aquatic biomes worldwide. This pattern describes the changing structure and productivity of the predator-prey biomass pyramid, which represents the biomass of communities at different levels of the food chain. Scaling exponents of the relation between predator versus prey biomass and community production versus biomass are often near ¾, which indicates that very different communities of species exhibit similar high-level structure and function...
Study prompts Washington to revamp cougar hunting September 26, 2012 Summit County Citizens Voice
Effects of male trophy hunting on female carnivore population growth and persistence RB Wielgus, DE Morrison, HS Cooley, B Maletzke - Biological Conservation, 2013
... Light hunting of males (no net male immigration) decreased female population growth in an additive manner and heavy hunting of males (increased net male immigration) decreased female population growth in a depensatory manner. We reject the compensatory mortality hypothesis, and suggest that hunting of male carnivores has a negative additive or depensatory effect on female population growth depending on the intensity of male mortality. We recommend that hunting of polygnous carnivores not exceed their intrinsic growth rates to forestall excessive compensatory male immigration and infanticide. The Washington Department of Fish and Wildlife instituted a new “equilibrium” hunting management plan (hunting mortality < 14%/year) for cougars in 2013 based on our findings and recommendations.
L. Mark Elbroch, Patrick E. Lendrum, Jesse Newby, Howard Quigley, Derek Craighead December, 2013
... We tested for seasonal differences in cougar (Puma concolor) foraging behaviors in the Southern Yellowstone Ecosystem, a multi-prey system in which ungulate prey migrate, and cougars do not. We recorded 411 winter prey and 239 summer prey killed by 28 female and 10 male cougars, and an additional 37 prey items by unmarked cougars. Deer composed 42.4% of summer cougar diets but only 7.2% of winter diets. Males and females, however, selected different proportions of different prey; male cougars selected more elk (Cervus elaphus) and moose (Alces alces) than females, while females killed greater proportions of bighorn sheep (Ovis canadensis), pronghorn (Antilocapra americana), mule deer (Odocoileus hemionus) and small prey than males. ... Elk and deer migrations may also be sustaining stationary cougar populations and creating apparent competition scenarios that result in higher predation rates on migratory bighorn sheep in winter and pronghorn in summer
Good Nutrition Limits the Effect of Mountain Lion and Coyote Predation
Effect of Enhanced Nutrition on Mule Deer Population Rate of Change (July 2009) Wildlife Monographs, Volume 172, Issue 1, pages 1–28 Chad J. Bishop, (Colorado Division of Wildlife), Gary C. White, David J. Freddy, Bruce E. Watkins, Thomas R. Stephenson
ABSTRACT ... By manipulating nutrition and leaving natural predation unaltered, we determined whether habitat quality was ultimately a critical factor limiting the deer population... Our results demonstrate that observed coyote predation, by itself, is not useful for evaluating whether coyotes are negatively impacting a deer population. Our results also indicate that mountain lions may select for deer in poorer condition under some circumstances, suggesting that mountain lion predation may not always be an additive source of mortality. Disease mortality rates of adult females did not decline in response to enhanced nutrition. Winter-range habitat quality was a limiting factor of the Uncompahgre Plateau mule deer population...
If you have deer, you have mountain Lions - Not
This is a common warning about deer, but lions and bears are searching for food everywhere:
Another wild animal sighting in Spanish Fork October 6, 2016 Utah, Good4Utah
... Tuesday, a cougar was spotted roaming in a neighborhood ... "They're usually following deer and we don't have deer," said Seamons [Utah division of wildlife]...
State cougar plan will incorporate new monitoring, computer models December 11, 2016 Montana, The Missoulian
Mountain lion predation and livestock September 25, 2016 North Dakota, CattleNetwork.com
... Of the 14 animals evaluated ... Half of the cougars had either mule deer or white-tailed deer in their system. Other native species found in the intestines included jackrabbits, porcupines, beavers, badgers, minks and other rodents. Porcupine remains were found in two of the animals and 87 percent of the cougars had porcupine quills in their skin or flesh...
Cougars in the crosshairs November 16, 2015 Oregon, The Register-Guard
... If cougars were responsible for declines in mule deer, and if killing cougars would reverse the declines, there might be some justification for the target areas. But mule deer populations have been falling for half a century, before and after Measure 18. The primary reason is not predation, but a decline in the quantity and quantity of forage ...
Cougars unlikely to settle in Minnesota, Wisconsin November 15, 2015 Duluth News Tribune
... With breeding populations already established in Nebraska and the Dakotas, the cougar could further expand into southern Missouri, eastern Oklahoma and northern and western Arkansas, the study found... Cougars expand their range by what is called “stepping stone dispersal” ...
It's not just Cecil: Trophy hunting is threatening mountain lions right here in the US November 13, 2015 Washington, Washington Post
... nearly half a dozen states ... have proposed an increase in cougar hunting quotas for a variety of reasons, including the desire to reduce human conflict, protect livestock or increase native deer populations. ...The harvest rate is currently set at 12 to 16 percent of the population. Wielgus’s research in Washington, along with other studies in Montana, has suggested that cougar populations tend to increase at a rate of 12 percent ...
Predators and Prey—A Case of Imbalance Mountain Lions and the North Kings Deer Herd From the June 1989 issue of "Forest Research West"
... The focus of the study was the North Kings deer here, a population of California mule deer. This herd declined from an estimated 17,000 animals in 1950 to about 2,000 animals in 1988. While the initiation of the decline was probably a result of overpopulation in the 1940s and 1950s, the lack of recovery seems to be related to heavy predation... The research team captured 96 newborn fawns and equipped them with radio collars over a 7-year period from 1979 to 1985... During the 7 years of the study, fawn survival ranged from 13% to 42% and averaged 38%. Two percent were killed in accidents, 9% died from disease or birth defects, and predators were responsible for the deaths of 51% of the fawns. Of those taken by predators 3% were killed by bobcats, 22% by bears, 27% by coyotes, and 49% by mountain lions... The bottom line is that in the study area, mountain lions appear to be controlling an already depressed deer herd, and they are apparently not benefiting the population by taking only the weak and old.
Top-down versus bottom-up forcing: evidence from mountain lions and
mule deer Becky M. Pierce, Vernon C Bleich, Kevin L. Monteith, and R. Terry Bowyer
Journal of Mammalogy, 93(4):977–988, 2012
Abstract: We studied mountain lions (Puma concolor) and mule deer (Odocoileus hemionus) inhabiting a Great Basin ecosystem in Round Valley, California, to make inferences concerning predator–prey dynamics... For mule deer, bitterbrush (Purshia tridentata) in diets, per capita availability of bitterbrush, kidney fat indexes, fetal rates (young per adult female), fetal weights, and survivorship of adults and young indicated that the period of decline was typical of a deer population near or above the
carrying capacity (K) of its environment. Numbers of mountain lions also declined, but with a long time lag... predation, mostly by mountain lions, was likely additive during the period of increase and thus, top-down forcing slowed but did not prevent population growth of mule deer. These outcomes indicate that resource availability (bottom-up processes) has an ever-present effect on dynamics of herbivore populations, but that the relationship can be altered by top-down effects. Indeed, top-down and bottom-up forces can act on populations simultaneously and, thus, should not be viewed as a stark dichotomy.
Variation in cougar (Puma concolor) predation habits during wolf (Canis lupus) recovery in the southern Greater Yellowstone Ecosystem
TD Bartnick ... Canadian Journal of Zoology, 2013
We examined predation habits of cougars (Puma concolor (L., 1771)) following the recent recovery of gray wolves (Canis lupus L., 1758) in the southern Greater Yellowstone Ecosystem... We predicted that as wolves recolonized their former range, competitive exclusion would compel cougars to cede portions of niche space occupied in the absence of wolves... As wolf numbers increased and the mean distance between wolf pack activity centers and cougar predation sites decreased, cougars made kills at higher elevations on more north-facing slopes during summer and in more rugged areas during winter. In addition, cougars preyed on a higher proportion of mule deer ... consistent with predictions of exploitative competition with wolves. Observed changes in predation characteristics reflect differences in predation strategy between cougars and wolves, given that wolves are coursing predators and cougars are ambush predators...
Metrics of predation: perls of predator-prey ratios RT Bowyer ...Acta Theriologica, 2013
We developed an original modeling approach using program Stella® to investigate the usefulness of predator–prey ratios (PPRs) for interpreting top-down and bottom-up forcing on moose ... The resulting patterns of PPRs were impossible to disentangle from one another, and did not provide reliable insights into whether top-down or bottom-forcing occurred, especially over short time spans where critical decisions related to management of moose and wolves might be necessary ... We provide an alternative method to using PPRs or other predation metrics for determining whether top-down or bottom-up forcing is occurring by adopting an approach based on the physical condition and life-history characteristics of prey....
Is anthropogenic cougar mortality compensated by changes in natural mortality in Utah? Insight from long-term studies ML Wolfe, DN Koons, DC Stoner, P Terletzky, EM Gese… - Biological Conservation, 2015
... If rates of human exploitation exceed natural mortality, however, such actions will ‘add’ to overall mortality and could imperil the sustainability of such actions. We applied competing risk analyses to 16 years of data for heavily harvested and semi-protected cougar populations in Utah to test the additive and compensatory mortality hypotheses, while accounting for parameter uncertainty... we could not reject the additive mortality hypothesis when uncertainty in parameter estimates was accounted for. In the semi-protected population, however, we detected evidence for partial compensation of increased anthropogenic exploitation via reductions in natural mortality. As may be common in carnivore studies, we found that ignoring uncertainty in estimates of cause-specific mortality systematically led to biased conclusions regarding additive and compensatory mortality hypotheses...