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|  TPWD News Release 20070917c                                            |
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[ Note: This item is more than seven years old. Please take the publication date into consideration for any date references. ]
[ Media Contact: Tom Harvey, 512-389-4453, tom.harvey@tpwd.texas.gov ] [TH]
Sept. 17, 2007
Mountain Lion Research Sheds Light on Elusive Feline
AUSTIN, Texas -- New genetic research adds to a body of evidence indicating mountain lion populations are generally healthy in parts of Texas, with significant populations in West and South Texas and harvest data pointing to stable or increasing numbers in the western part of the state over the past 90 years.
The research paper "Genetic structure of mountain lion (Puma concolor) populations in Texas and implications for management" was largely completed in 2006 and is now being prepared for publication in scientific journals. The primary author is Jan Janecka, Ph.D., a post-doctoral research associate at Texas A&M University-College Station. Texas Parks and Wildlife Department Mammalogist John Young is a co-author, along with Michael Tewes, Lon Grassman, Jr., Jacob Garza, and Rodney Honeycutt. TPWD funded the study, which was done by the Feline Research Center of the Caesar Kleberg Wildlife Research Institute at Texas A&M University-Kingsville.
Researchers examined the genetic structure of mountain lions from six areas of Texas, conducting DNA analysis of tissue samples from 89 lions. Although all the lion samples came from Texas, scientists say the genetic traits likely reflect a region that encompasses parts of northern Mexico and southern New Mexico as well. Scientists found evidence that there is likely a core mountain lion population in and around Big Bend National Park. Researchers also concluded that a lack of connection between lions in West and South Texas indicates dissimilar populations in those areas.
One study finding that has been misunderstood by some and needs careful clarification is that the long-term effective population size for mountain lions in Texas was estimated to be 5,607 animals. As author Janecka explains, this genetic "effective population" is not the same as the actual or census population. It represents hundreds of generations of lions over recent evolutionary history, and there is no correlation between this type of long-term estimate and the current census population of lions in Texas.
"An effective population represents, from a genetic standpoint, the population size that would behave genetically like the actual or census population," Janecka said. "Another way to state this is the genetic effective population reflects the effect a breeding population has on an animal population's genetic diversity and structure."
Janecka makes a key point: "Typically, effective populations are smaller than census populations."
Another key finding involves the genetic health or diversity of Texas lions. Janecka says the value of genetic diversity is a bit of a contentious topic, but what research shows is when a population becomes isolated and animals start inbreeding and the genetic diversity decreases, researchers have documented effects such as lower survival rates of juveniles, low body weights, decreased disease resistance and other problems.
"Our research shows that Texas mountain lions are not likely subject to negative fitness effects associated with low genetic diversity," Janecka said. "At least in West Texas, genetic diversity was similar to other mountain lion populations in other western states and contiguous states. The South Texas genetic diversity was lower, but not so much that you would see inbreeding effects."
Cougars are currently classified as nongame animals in Texas and may be taken by anyone who possesses a valid hunting license, with no season or bag limits. This prompts occasional questions about whether the current regulatory approach is sustaining healthy lion populations in the state.
Michael Tewes, PhD, a faculty advisor at A&M-Kingsville for the genetics study, is one of the elder statesmen of wild cat research in North America. For 25 years, he's been supervising and reviewing research on mountain lions, ocelots and other wild cats.
"We don't have an accurate population estimate for mountain lions in Texas," Tewes acknowledges. "They are difficult to census, being nocturnal, sensitive, wide ranging, and by nature a low density species." Still, he and other experts believe Texas lion numbers are stable, at least in some areas.
"I think mountain lion populations have been sustaining themselves for decades in South and West Texas, so they have been tolerating existing levels of harvest," Tewes said.
Since 1919, the government agency responsible for nuisance wildlife control has kept records of mountain lions trapped in Texas. Now called Texas Wildlife Services, this agency's harvest data show a widely-fluctuating trend line over the decades, with the total number of lions taken each year occasionally dipping to the single digits in the 1920s and 1970s, occasionally spiking up above 50 lions per year, but mostly staying between 30-to-50 per year in recent decades. These are almost all lions trapped at the request of rural landowners, usually due to concerns about lions killing livestock, and mostly in West Texas. A plot of harvest data since 1919 shows an increase over time.
"Wildlife Services deals with wildlife damage complaints, so the assumption is if they're receiving more requests for nuisance control, lion populations may be increasing," Young said. "Harvest statistics are not an exact way to measure wildlife populations, but they are a primary tool used in many states to get some sense of population trends."
Young says the effect of harvest on mountain lion populations differs depending on the sex and age of cougars removed. Some studies suggest cougar populations can sustain harvest rates of up to 20-to-30 percent, and even at higher levels exceeding 40 percent populations appear to be able to recover within 3-to-5 years or less after harvest is reduced.
In a separate three-year South Texas research study completed in 1997, researcher Louis Harveson captured and radio-collared 19 mountain lions. Tewes also supervised and reviewed this work, and recalls a key finding regarding what lions eat.
"The food habits study Harveson and I published showed South Texas mountain lions ate primarily white tailed deer, followed by feral hogs and javelina," Tewes said. "Out of 75 prey animals killed by lions in the study, only seven were livestock--a longhorn calf and 6 sheep. Most studies show mountain lions are generally not a major problem for livestock, but locally you do sometimes get individual lions that are problems for landowners, and those can typically be removed by Wildlife Services."
Of the 19 lions radio-collared by Harveson, 10 died during the three-year study, one from natural causes, one from an unknown reason, one during research capture, two taken by trappers and five killed by hunters. (Several of the female lions in this study were cubs and subadults, known to be at higher risk of mortality.) Other studies have showed higher survival rates. A three-year study at Big Bend Ranch State Park in the mid-1990s found slightly more than half of male lions survived, with female survival at 70 percent. A 1980s study at Big Bend National Park showed annual male survival at more than half, with female survival at 68 percent. It's worth noting these older studies may not reflect recent changes in land use and landowner attitudes, which may favor mountain lions.
There is some evidence that mountain lions may be expanding their range.
"There is a phenomenon occurring across North America, where mountain lions have begun to appear in places where they haven't been seen in decades, in Iowa and Nebraska and other places," Young said. "The anecdotal observation is that mountain lions may be moving back into habitat where they haven't been for decades. That could be happening in Texas, but we really don't have a scientific basis to say that. We are getting an awful lot of sightings in urban and suburban areas, but we are typically unable to confirm those with physical evidence."
TPWD gets more than 500 reports of mountain lion sighting per year, but less than one percent are ever verified by physical evidence such as tracks, scat or photographs.
"Generally, mountain lions pose a minimal risk to outdoor enthusiasts," said Tewes. "There have been only a few instances of attacks on humans in the modern era, including a couple in West Texas and others in the past century across the U.S. Often these involve starving lions attacking smaller people such as children or small women. In urban and suburban areas of Texas, I wouldn't be overly concerned about lion attacks. Mountain lions are typically afraid of humans."
Texans' attitudes and beliefs about mountain lions differ in some respects, but a majority of citizens value lions as part of the state's natural heritage. This was demonstrated by a public survey research project completed in 2002 by another A&M-Kingsville graduate student, Iliana Peņa. Of those surveyed, urban residents were more likely to have positive beliefs about mountain lions, but 84 percent of all respondents believed mountain lions are an essential part of nature, and 74 percent believed efforts should be made to ensure their survival in Texas. Interestingly, views among rural landowners differed depending on where in the state they owned property.
"In West Texas and the Hill Country, many ranchers are concerned about livestock depredation, particularly where sheep and goat operations are active, whereas in South Texas I think many landowners see mountain lions more as a novelty and many ask hunters not to shoot them," said Tewes, who also supervised and reviewed Peņa's research. "The density of lions is lower in South Texas, and that may be a factor."
Public support to ensure the survival of mountain lions is reflected in TPWD's recently completed Texas Wildlife Action Plan, which lists low, medium and high priority wildlife species of concern, the location and condition of key habitats, threats or problems to species or habitat, needed conservation actions and recommended species and habitat monitoring. The most recent version of the book Mammals of Texas says the state has 184 species of mammals. "Only 65 of those mammalian species made the action plan list and mountain lions were one," Young said. The plan's mammal committee comprised of mammalogists, private individuals, zoos, and conservation organizations recommended mountain lions be placed on the medium priority tier.
"We did this genetic study to see if it could be an effective way to examine the health of mountain lion populations in our state," Young said. "Follow-up research is needed to get a better idea of the genetics of our state population. But it's a good start, a baseline from which we can move forward. After the current generation of lions passes--and lions can live as long as 10-to-12 years--we can look at it again. But meantime we're still filling in the genetic picture, so we'd like to get tissue samples from any lion mortalities in Texas."
"We may not be able to count the exact number of mountain lions in Texas, but we know a lot about them and we have been continuously, steadily working over the years to gain more knowledge," Young concluded. "We want to see them continue to be an important part of the ecology of Texas."
Anyone who wishes to report a dead mountain lion may contact Young at john.young@tpwd.texas.gov or (512) 912-7047. Basic information about mountain lions, including links to the brochures "Mountain Lions in Texas" and "Field Guide to the Mountain Lions of Texas," is on the TPWD Web site. "Mountain Lions in Texas" includes phone numbers for TPWD Wildlife Division offices across the state, as well as guidance for people who encounter mountain lions or live in areas inhabited by lions.
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On the Net:
http://www.tpwd.state.tx.us/huntwild/wild/species/mlion/
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