Fetherman E.R.,Colorado Parks and Wildlife |
Winkelman D.L.,Colorado State University |
Baerwald M.R.,University of California at Davis |
Schisler G.J.,Colorado Parks and Wildlife
PLoS ONE | Year: 2014
Myxobolus cerebralis caused severe declines in rainbow trout populations across Colorado following its introduction in the 1980s. One promising approach for the recovery of Colorado's rainbow trout populations has been the production of rainbow trout that are genetically resistant to the parasite. We introduced one of these resistant crosses, known as the GRxCRR (cross between the German Rainbow [GR] and Colorado River Rainbow [CRR] trout strains), to the upper Colorado River. The abundance, survival, and growth of the stocked GRxCRR population was examined to determine if GRxCRRs had contributed offspring to the age-0 population, and determine whether these offspring displayed increased resistance and survival characteristics compared to their wild CRR counterparts. Apparent survival of the introduced GRxCRR over the entire study period was estimated to be 0.007 (±0.001). Despite low survival of the GRxCRRs, age-0 progeny of the GRxCRR were encountered in years 2008 through 2011. Genetic assignments revealed a shift in the genetic composition of the rainbow trout fry population over time, with CRR fish comprising the entirety of the fry population in 2007, and GR-cross fish comprising nearly 80% of the fry population in 2011. A decrease in average infection severity (myxospores fish-1) was observed concurrent with the shift in the genetic composition of the rainbow trout fry population, decreasing from an average of 47,708 (±8,950) myxospores fish-1 in 2009 to 2,672 (±4,379) myxospores fish-1 in 2011. Results from this experiment suggest that the GRxCRR can survive and reproduce in rivers with a high prevalence of M. cerebralis. In addition, reduced myxospore burdens in age-0 fish indicated that stocking this cross may ultimately lead to an overall reduction in infection prevalence and severity in the salmonid populations of the upper Colorado River.
News Article | November 13, 2015
This story has been updated. In July, the death of Cecil the lion in Zimbabwe at the hands of trophy hunter Walter Palmer sparked international outrage, incited widespread debate about the ethics of trophy hunting, and provoked calls to the U.S. government to ban the import of trophies from other countries. But some conservationists are arguing that people in the United States should be paying more attention to the trophy hunting of our own lions — mountain lions, that is. The Humane Society of the United States, along with other wildlife advocacy groups, has expressed concern numerous times in the past few years about proposals by state wildlife agencies to increase cougar hunting without considering the best science on cougar management, or taking majority public opinion into account. Such hunts are almost exclusively carried out for sport or trophies. Currently, the only cougar populations in the country that have federal protection are the Florida panther and the Eastern cougar, the latter of which is believed extinct and has been proposed for delisting under the Endangered Species Act. Most other populations are unprotected and spread throughout the West, where the only state that currently forbids cougar hunting is California. In the past year, nearly half a dozen states — including Colorado, New Mexico, Oregon, Utah and Washington — 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. These proposals have been made despite recent research suggesting that overhunting actually causes more conflicts with humans. One of the most recent instances occurred in Washington state, where Gov. Jay Inslee just reversed a controversial new rule from the state’s wildlife management agency that would have expanded cougar hunting, allowing a harvest rate of up to 21 percent of the population in some areas, without allowing for a public comment period first. The new rule was hastily passed during an April meeting of the Washington Fish and Wildlife Commission and met with immediate outrage from advocacy groups, including the Humane Society, which appealed the decision. The expanded hunting was proposed for regions of the state also occupied by wolves in an attempt to quell the concerns of citizens concerned that living in close proximity to two large predators — instead of just one — could cause an increased risk of conflict. The wolf is a protected species in Washington and currently cannot be hunted, so the state proposed cutting down on cougars. But a cougar harvest rate of 21 percent would have likely only produced more problems, according to Rob Wielgus, director of the Large Carnivore Conservation Lab at Washington State University, who has been at the forefront of cougar research for the past several decades. Killing off too many cougars can cause demographic problems in the cats’ populations, Wielgus said. Male cougars are territorial. If you kill off one male, other (usually younger) males will move into the area to take his place. Invading younger males will seek out females in the territory and frequently kill any existing cubs in order to make room for their own offspring. This influx of young males can cause a number of conflicts. First, young male cougars tend to “get in trouble,” said Howard Quigley, puma program director for Panthera, a global wild cat conservation organization. “It’s kind of like in a human society, if you had a bunch of teenagers running around,” he said. These young males are the ones usually responsible for preying on livestock and otherwise causing problems with humans, said Wielgus. Additionally, female cougars often go into hiding to protect their cubs if younger males start invading their territories, Wielgus added. This means they sometimes end up hiding out in places they previously didn’t inhabit and start eating animals they didn’t prey on before. “Basically the bottom line was this heavy hunting of cougars was actually causing all the problems we were seeing,” Wielgus said of his work in Washington. Cougar-related problems in the state largely dissipated once an appropriate hunting quota was established, according to Wielgus. 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 — meaning a hunting quota of 12 percent or lower is best for maintaining stable cougar populations and minimizing conflict with humans. But state wildlife management agencies don’t always want to abide by the 12-percent quota — and it’s not just limited to Washington. In Utah, state wildlife management officials decided this year to slightly increase cougar hunting quotas in an effort to protect mule deer and bighorn sheep. In its updated cougar management plan, the Division of Wildlife Resources points to a set of management guidelines from 2005 that suggest cougar populations can sustain a harvest rate of 20 to 30 percent of the population, while also acknowledging Wielgus’ more recent research that indicates the average growth rate of a cougar population is 12 percent. And in Colorado, state officials recently proposed increasing harvest rates in certain areas, mostly surrounding the town of Westcliffe, by up to 46 percent in a research project aimed at doubling local mule deer populations. The proposal would have increased the harvest limit in the area from 24 cats to 35 — potentially up to 50 percent of the cougar population in that area, according to Wendy Keefover, native carnivore protection manager for The Humane Society of the United States. This proposal was later withdrawn. But it’s not just the increase in hunting quotas that’s bothering scientists and conservationists. It’s the reasons for doing so. In several recent cases, the rationale behind proposing an increased harvest is to protect livestock or increase prey populations, frequently mule deer. This was the case in Colorado, and was also the motivation behind a recent decision in Oregon to increase hunting by 25 percent. The Oregon Department of Fish and Wildlife pointed to recent research indicating that elk populations in the state increased when cougars were removed. But there have also been at least four studies so far indicating that removing cougars doesn’t do much to help mule deer populations, according to Quigley, the Panthera puma expert. Such research suggests that habitat degradation is the critical factor in declining mule deer. Additionally, Keefover pointed to research from the U.S. Department of Agriculture suggesting that predators, and particularly cougars, account for a relatively small percentage of losses in livestock. And out of the livestock killed by predation, cougars usually accounted for less than 10 percent of the losses, although this number can rise as high as 15 percent for sheep and lambs in some areas. Still, losses due to predation can add up to millions of dollars per year, so it’s an issue that the industry takes seriously. The problem, Wielgus said, is that pressure from lobbying groups can cause wildlife agencies to enact management practices meant to appease the industry without taking the best science into consideration. On top of this, the public is sometimes not given an adequate opportunity to voice its opinion on proposed management changes, Keefover said. Washington is just one example. When the Colorado proposal was being considered, for instance, the Humane Society decried the Parks and Wildlife Commission’s failure to hold more than one hearing and give the legally required 30 days notice for public comment in a letter to the Commission. When that proposal was withdrawn, the Colorado Division of Wildlife cited “the extensive amount of comment provided by the public in response to the draft proposal to evaluate the relationship between mountain lion and mule deer populations, and to allow for additional public comment and participation,” as the reason in a release. “I think there’s this public antipathy to trophy hunting cougars at the same time we have all these agencies pushing for more trophy hunting,” Keefover said. But it does seem that there’s some hope for the cougar. While increased hunting has been proposed in a handful of states in the past year, it’s only been finalized in a few, including New Mexico, Utah and Oregon. In other places, such as Washington and South Dakota, the rules were overturned. And in Nebraska, state Sen. Ernie Chambers is pushing to end cougar hunting, which has been allowed for several years now, on a population believed to number fewer than 30 individuals. The cougar’s story can be thought of as a “two-edged sword,” according to Quigley. “It’s a wonderful success story that we still have this large carnivore across most of the Western states and they’re increasing their pawprint into the Midwest,” he said. “That really to me says that we’re creating the environment for the expansion of mountain lions in North America. “On the other hand,” he added, “I think it’s these steps backward that really worry me and other lion biologists in that it seems like there’s much more difficulty with these game agencies to come to grips with accepting some of these modern approaches.” Correction: An earlier version of this article stated that the Colorado Parks and Wildlife Commission is legally obligated to hold three hearings and a 30-day public comment period on a proposed regulatory change. While the public comment period is mandatory, three hearings are not required by law.
News Article | November 24, 2015
Prosecutors declined to press charges against the hunter for the April killing after a joint investigation conducted by federal and state authorities concluded that he did not intend to shoot the wolf, the U.S. Fish and Wildlife Service said in a statement. It is illegal to kill wolves without a special permit in most of the Lower 48 states, where the animals are protected under the U.S. Endangered Species Act. Authorities allow the animals to be legally hunted in Idaho and Montana. The Endangered Species Act imposes criminal penalties on anyone who knowingly violates the federal law. "Our investigation determined that the shooting resulted from misidentification rather than the intentional take of a protected species," said Dan Rolince, the fish and wildlife service's regional assistant special agent in charge. The man, who has not been named, was legally hunting coyotes near the town of Kremmling when he shot the wolf, the statement said. When the hunter realized his mistake he immediately notified Colorado Parks and Wildlife officials, authorities said, adding that DNA testing performed at a forensic laboratory in Oregon confirmed it was a gray wolf. Michael Robinson, a conservation advocate with the Center for Biological Diversity, said the shooter violated the first rule of hunting by not identifying his target before firing. "The Justice Department should resume prosecuting those who kill endangered wildlife, and the Interior Department should develop a national wolf recovery plan to ensure that the fate of wolves in an entire state cannot be determined by any number of negligent or rogue shooters," he said. Robinson said "the word is out" among people who illegally kill wolves that they can avoid prosecution by claiming that they thought they were shooting a coyote.
News Article | December 16, 2016
Colorado To Kill Some Mountain Lions, Bears To Boost Mule Deer Numbers The Colorado Parks and Wildlife Commission has approved a plan to kill some mountain lions and black bears. It's part of a plan the commission hopes will decrease the number of predators to help boost the state's mule deer population. Under the plan, state wildlife crews will capture and kill up to 15 mountain lions and 25 black bears each year in the Piceance Basin of northwest Colorado. beginning in the spring of 2017. The state said it would also pay $435,000 per year for a nine-year study of the "effects of mountain lion population density on mule deer populations." The Fort Collins Coloradoan reported the total cost of the wildlife population management plan will be $4.5 million. The state estimates more than 400,000 mule deer live in Colorado, which the Parks and Wildlife Commission says is about 80 percent of the target population. Colorado allows people to hunt mule deer each year if they obtain a permit from the state. The required licenses cost $34 for Colorado residents, and more than $300 for hunters from out-of-state. Last year, about 34,000 mule deer were legally killed by hunters in Colorado according to the Parks and Wildlife Commission. On its website, the commission said its motivation was not to sell more licenses to hunt deer. "Revenues were not a factor in determining where and how to proceed," it says on a page titled "Predator Management Q & A." Colorado State University wildlife biologists told the Denver Post earlier this week they believe the plan contradicts the state commission's own science: " 'We find it surprising that [Colorado Parks and Wildlife's] own research clearly indicates that the most likely limiting factors for mule deer are food limitation, habitat loss and human-induced disturbance – not predators,' [Colorado State University] biologists Joel Berger, Kevin Crooks and Barry Noon wrote in a Saturday letter to CPW commissioners. "The biologists point to vast deer habitat in Colorado that has been fragmented by roads, damaged by oil and gas drilling and rendered inhospitable for wildlife by other development. " 'We do not understand why compelling scientific findings based on research conducted in Colorado by CPW researchers is not being used to better inform management actions to benefit mule deer,' they wrote. 'This seems both illogical and a waste of public funds. The scientific consensus is clear and compelling – predator control is a costly and ineffective management tool to increase mule deer populations.' " On its website, the Parks and Wildlife Commission refuted the biologists' claims, writing, "Ongoing research in the Piceance Basin suggests predation rather than other factors (habitat, energy development) is most likely limiting this population." "Habitat is a primary focus in other areas where habitat may be more limiting than the two areas where the influence of predation is being examined," it continued.
Iwasaki Y.,Colorado State University |
Iwasaki Y.,Toyo University |
Brinkman S.F.,Colorado Parks and Wildlife
Environmental Toxicology and Chemistry | Year: 2015
Increased concerns about the toxicity of chemical mixtures have led to greater emphasis on analyzing the interactions among the mixture components based on observed effects. The authors applied a generalized linear mixed model (GLMM) to analyze survival of brown trout (Salmo trutta) acutely exposed to metal mixtures that contained copper and zinc. Compared with dominant conventional approaches based on an assumption of concentration addition and the concentration of a chemical that causes x% effect (ECx), the GLMM approach has 2 major advantages. First, binary response variables such as survival can be modeled without any transformations, and thus sample size can be taken into consideration. Second, the importance of the chemical interaction can be tested in a simple statistical manner. Through this application, the authors investigated whether the estimated concentration of the 2 metals binding to humic acid, which is assumed to be a proxy of nonspecific biotic ligand sites, provided a better prediction of survival effects than dissolved and free-ion concentrations of metals. The results suggest that the estimated concentration of metals binding to humic acid is a better predictor of survival effects, and thus the metal competition at the ligands could be an important mechanism responsible for effects of metal mixtures. Application of the GLMM (and the generalized linear model) presents an alternative or complementary approach to analyzing mixture toxicity. © 2015 SETAC.
Hooten M.B.,U.S. Geological Survey |
Hanks E.M.,Colorado State University |
Johnson D.S.,National Oceanic and Atmospheric Administration |
Alldredge M.W.,Colorado Parks and Wildlife
Journal of Animal Ecology | Year: 2013
Analyses based on utilization distributions (UDs) have been ubiquitous in animal space use studies, largely because they are computationally straightforward and relatively easy to employ. Conventional applications of resource utilization functions (RUFs) suggest that estimates of UDs can be used as response variables in a regression involving spatial covariates of interest. It has been claimed that contemporary implementations of RUFs can yield inference about resource selection, although to our knowledge, an explicit connection has not been described. We explore the relationships between RUFs and resource selection functions from a hueristic and simulation perspective. We investigate several sources of potential bias in the estimation of resource selection coefficients using RUFs (e.g. the spatial covariance modelling that is often used in RUF analyses). Our findings illustrate that RUFs can, in fact, serve as approximations to RSFs and are capable of providing inference about resource selection, but only with some modification and under specific circumstances. Using real telemetry data as an example, we provide guidance on which methods for estimating resource selection may be more appropriate and in which situations. In general, if telemetry data are assumed to arise as a point process, then RSF methods may be preferable to RUFs; however, modified RUFs may provide less biased parameter estimates when the data are subject to location error. © 2013 The Authors. Journal of Animal Ecology © 2013 British Ecological Society.
News Article | April 5, 2016
The study calls for more scrutiny of and a more holistic approach to current management efforts. Hunting provides substantial economic benefits for states. Deer and elk hunters in Colorado, for example, must apply for permits annually. A deer license for non-residents runs $432; a permit for in-state residents is $43. A license to hunt elk is nearly $500 for non-residents; the in-state charge is $48. Nearly $2 million from these fees support wildlife management and public land conservation in the state each year. "There's this notion that habitat management that's good for game species is good for all wildlife," said Travis Gallo, Ph.D. student in the Department of Fish, Wildlife and Conservation Biology, and lead author of the study. "There's a lot of money that goes into habitat management for game species, and we wanted to see if there were any synergies between game management and conservation of species that were not the target of management actions." While conducting a review of published papers, Gallo said that he and Associate Professor Liba Pejchar, also in the Department of Fish, Wildlife and Conservation Biology, switched gears once they saw the lack of scientific research on the topic. The duo ended up writing an opinion piece or perspectives essay on the issue. "We found only 26 studies that measured the direct and indirect effects of game management efforts on non-game animals," said Gallo. Among the studies that did measure the effects of game management on non-game species, they found both positive and negative effects: a study of sage grouse management in the Western U.S. found that conservation efforts would likely protect 13 songbird species, while a study in Spain found that an increased abundance in wild boar, red deer and aoudad sheep decreased resources for native species. The team also found instances where there were no effects. For example, a study that looked at prescribed fire on lizard abundance in central Texas found no short-term effect on other species. Gallo said that one way to even the management playing field is to create new funding sources for wildlife conservation. The federal Pittman-Robertson excise tax—which was implemented in 1937—has successfully raised more than $10.1 billion from sales on sporting goods that involve hunting, like ammunition and guns, fishing rods and reels. In 2009, following a similar model, a group of more than 6,300 state fish and wildlife agencies, biologists, hunters, birdwatchers and others proposed the Teaming with Wildlife Act, which would have provided additional funding for wildlife preservation through a small tax on all outdoor gear, including camping gear, binoculars and outdoor apparel. This bill, however, failed to pass through Congress. Gallo said that there's talk in the conservation community about reviving this sort of proposal. "A tax like this would not only increase funding for conservation, but it may create a sense of investment by those people that are now helping pay for conservation," he said. Gallo—who will graduate in May—said his research provides a good example, and hope, for the type of holistic approach that is needed. "My research is piggy-backed on a mule deer experiment in northwestern Colorado," he said. "Colorado Parks and Wildlife was removing pinyon-juniper trees to increase the shrubs and grasses that mule deer like to eat. We collaborated with them and added another layer of research to assess the effects that this management may have on all the other birds and mammals in the area." "The hunting and fishing communities contribute a lot of money and effort to wildlife management," he added. "If you can find synergies between management for hunted species and conservation for biodiversity, we would be more effectively and holistically managing the land." The article, "Improving habitat for game animals has mixed consequences for biodiversity conservation," was published in advance online in Biological Conservation. The study will appear in the May print issue of the journal. Explore further: Green sea turtles of Florida, Mexico no longer 'endangered' More information: Travis Gallo et al. Improving habitat for game animals has mixed consequences for biodiversity conservation, Biological Conservation (2016). DOI: 10.1016/j.biocon.2016.02.032
Stacy W.L.,Colorado Parks and Wildlife |
Lepak J.M.,Colorado Parks and Wildlife
Science of the Total Environment | Year: 2012
Mercury (Hg) bioaccumulation in aquatic food webs has created a human health concern for anglers who consume fish. Variability in sport fish Hg concentration adds to the uncertainty of the amount of fish an angler can safely consume, so predicting where variability arises is useful. We evaluated the relative influence of diet (prey Hg concentration and energy density) and sex on sport fish Hg concentrations using a bioenergetics approach. Our results indicated that sport fish diets (prey Hg concentration followed by energy density) were the most important factors for determining sport fish Hg concentration followed by sex. Although physiological and behavioral differences based on sex may lead to differences in gross growth efficiency, resulting in different Hg concentrations in male and female sport fish, evaluating the relative importance of these differences will require sex-specific parameterization of bioenergetics models. Our results support previous findings that knowledge of sport fish diets (prey Hg concentration followed by energy density) and sex could aid in the prediction of sport fish Hg concentrations. Thus, basic knowledge of system-specific food web structure could provide valuable information for developing sport fish consumption advisories to better protect anglers and their families from Hg contamination. © 2012 Elsevier B.V.
News Article | March 20, 2016
The study also found that bears that eat human food don't survive as long as those left to the wild. Colorado Parks and Wildlife researcher Heather Johnson says the study was conducted because of increasing conflicts between bears and humans in Colorado. According to the Durango Herald (tinyurl.com/jl6rrre ), there are a lot more risks for small bears in towns because they can get hit by cars, separated from their mothers or electrocuted climbing power poles.
News Article | March 21, 2016
Black bears that eat human foods from trash cans have higher reproductive rates than those living on natural foods, according to a study by Colorado researchers. The study by researchers with Colorado Parks and Wildlife also found bears that eat human food don't survive as long as those left to the wild. The bears have been fitted with collars that track their location, helping researchers determine how the animals behave. The researchers use hair samples to find out how much processed human food the bears had been eating. Scent baits have been set up around the city of Durango to collect hair, the Durango Herald reported (http://tinyurl.com/jl6rrre ). The study was launched because of increasing conflicts between bears and humans in Colorado, researcher Heather Johnson said. "There's a lot more risks for a little bear in town," Johnson added. For example, small cubs can get hit by a car, separated from their mothers or electrocuted while climbing power poles. The study is being conducted in southwestern Colorado and is scheduled to end next winter. Wildlife officials say it's difficult to determine what happens to bears in other urban environments. "It's really tough problem: How many bears are out there, and what kind of impact are we having?" said Stewart Breck, a wildlife ecologist with the National Wildlife Research Center.