Billings, Mont. (AP) – Mountain lions, the largest members of
the cat family in North America, may be heartier eaters than some
researchers originally estimated.
“One of the most interesting things we found was how much more
prey they kill in summer,” said Kyle Knopff, lead author of a
three-year Canadian mountain lion study that was recently published
in the Journal of Wildlife Management. “Just how focused they
become on young of the year ungulates was surprising.”
Knopff is basing his conclusions on data collected from more
than 1,500 kill sites while tracking 54 cougars with GPS collars.
The collars allowed the University of Alberta researchers,
including Knopff’s wife Aliah, to move in quickly after a kill to
identify what was taken and by which lion.
In the journal article, Knopff writes that some previous studies
“may have failed to identify higher kill rates for large
carnivores in summer because methods in those studies did not
permit researchers to locate many neonates or because sample size
was too small.”
The use of GPS collars enabled Knopff and his colleagues to
collect more data. As a result, he found that mountain lions killed
more deer, elk and moose during the summer by focusing on juveniles
and actually killed fewer animals in winter. The information
contradicts previous studies conducted in Idaho.
“The Idaho estimates differed from our summer estimates by as
much as 365 percent in terms of frequency of killing and 538
percent in terms of prey biomass,” Knopff wrote. “Because kill
rate fundamentally influences the effect predators have on their
prey, the discrepancy between studies represents a substantial
difference in the capacity for cougars to impact ungulates.”
The study was conducted over 10 years in west-central Alberta,
including the Bow Valley, Jasper National Park, portions of Banff
National Park and in Clearwater County east of Banff. The terrain
of the study area was a mixture of lodgepole pine and spruce
forests at elevations ranging from 2,500 to 9,300 feet. The
mountain lions’ prey included deer, elk, bighorn sheep, coyotes,
feral horses, beaver and porcupines.
Cougars aren’t easy creatures to study. The secretive animals
range widely to hunt – 250 to 600 square miles for males, 60 to 125
square miles for females.
Adult male cougars can weigh 140 to 165 pounds. One male cougar
in Knopff’s study tipped the scales at 180 pounds and primarily fed
on moose and feral horses. Females typically weigh around 100
pounds. From nose to tail the big cats can measure 61/2 to 10 feet
long. The average lifespan for a male is 8 to 10 years, 12 to 14
Great leapers and sprinters, cougars kill by latching onto their
prey with their front claws and powerful forelegs and then biting
the windpipe or spine along the neck with their large canine teeth.
For smaller prey, lions may crush the animal’s skull. On rare
occasions lions have been known to attack humans.
“Our kill rate estimates indicate that adult cougars are highly
effective predators, killing at rates at the upper end of those
recorded for wolves in both frequency and biomass,” Knopff
In one prey encounter they studied, Knopff said a cougar brought
down a feral horse less than 30 yards from where it attacked.
“I think our study showed they are very efficient predators,”
Because of their adaptability, cougars are found from the Yukon
to the Andes of South America, a larger range than any other big
mammal in the Americas.
In studying cougar kill sites, the researchers publicized a
couple of interesting details. One is that that female mountain
lions with kittens kill more deer; the other is that adult male
lions kill larger but fewer animals.
“We had one male cougar kill 18 moose in less than a year,”
Based on the Canadian data, the cougars killed on average 0.8
ungulates (mainly whitetail deer and moose) a week, an average of
about 18 pounds a day. That statistic varied widely, though, based
on the individual – from a low of 0.24 ungulates to a high of 1.38,
or 18 to 41 pounds a day.
Those ungulates targeted tended to be young of the year or
adults with yearlings, largely because they were easier to
Deer made up more than 75 percent of the diet for adult female
lions in winter and summer. Adult males had a more varied diet,
concentrating on moose (36 percent) in the summer and deer (44
percent) in the winter. All told, adult males targeted large
ungulates for 62 percent of their diet. Subadult lions also ate
more deer than other species, but like human teenagers they also
varied their diet more opportunistically than adults.
On average, adult males killed an estimated 10,300 pounds of
biomass annually compared to 9,400 pounds killed by females with
Aliah Knopff said her portion of the study focused more on
cougar-human interactions and the lion’s habitat selection.
She said that as people have continued to build in more remote
areas, cougars have had to adapt.
“These are actually quite adaptable carnivores,” she said,
from changing their movements to become more nocturnal and avoid
humans, to finding undisturbed islands within development to live
in – such as along pipelines or well sites. The same can’t be said
for many other carnivores.
These more urban lions are mainly limited by human tolerance,
she said. The people in rural Alberta who were interviewed for the
study valued cougars highly, but not if they were killing pets or
“That’s the challenge for cougar conservation when the backyard
is becoming more overlapping,” she said.
Lion hunting is allowed in many Western states, including
Montana and Wyoming. Hunters track and tree the big cats with
hounds. Cougar kills are carefully regulated by state wildlife
Knopff writes that the Canadian study could be used by game
managers to better calculate mountain lions’ take of game animals
and in turn reduce lion numbers to benefit deer, elk and moose
populations. For example, hunting female cougars could reduce the
number of deer taken in a specific area.
But such management can also produce unpredictable outcomes, he
added. A lion population that is younger may lead to increased
confrontations with humans.