Mountain Lion Research Sheds Light on Elusive Feline
Written by TPWD 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 don¹t 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 Peña.
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 Peña'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 we¹re still
filling in the genetic picture, so we¹d 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.state.tx.us<mailto:john.young@tpwd.state.tx.us> This e-mail
address is being protected from spam bots, you need JavaScript enabled to
view it 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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