A camera trap study at Mendocino National Forest in Northern California reveals that black bears are capable of locating and stealing the remains of adult deer killed by pumas. This “kleptoparasitism” with bears, as scientists call it, reduces the calories that pumas eat in seasons when the bears are most active. Perhaps in response to this shortage, the puma hunt more often and eat more small games when the bears are not hibernating.
The results are published in the journal Basic and applied ecology.
Pumas, also known as mountain lions or cougars, are APEX predators, but that doesn’t mean they can’t be threatened by other carnivores, said the study’s lead author Max Allen, a research scientist at Illinois Natural History Study that studies large cats and other carnivorous mammals.
“Bears are mostly scavengers, and their large body size means they can take carcasses from apex predators,” said Allen. this is when they saw signs of a scat bear and carrying claw marks near a puma kill.
The researchers used GPS collars to track seven pumps across a 386-mile-long area over a two-year period. When a puma killed, he would visit it again or spend a lot of time in that place. The researchers visited these sites to record the types of animals the puma had killed and to find bear signs. They also set up camera bells at many of the slaughter sites to find out which animals were eating what was left.
The team recorded 352 puma killings, of which 64 were animals as well as deer. The smallest predators included dozens of squirrels, birds and rabbits, but also a coyote, two gray foxes, a fisherman and two black bears. The puma also went after meadows, which they can eat quickly, perhaps before they are found by a bear, Allen said.
The bears detected adult deer slaughter within about two days, cutting the feeding time of the pumas at deer antlers from 5-7 days in winter to about two days when the bears appeared.
The study found the highest frequency of puma killings ever reported. And the slaughter rate increased when bears were more active.
“There were only about 0.68 mountain lions per 100 square kilometers in our study area,” Allen said. “The average number was two or three. The average home area for a woman in Santa Cruz is between 30 and 35 square kilometers. But in Mendocino it was over 200.”
Despite the large tract of land available to them, pumas did not take full advantage of the killings. Their intake varied month-on-month, from more than 190 pounds of meat in January, when bears were at their lowest active, to less than 110 pounds in April. Bear scavenging of adult deer carcasses was at its highest in the warmer months, but the researchers found evidence of bears at puma slaughter each month of the year.
“We found evidence that the bears affect pumice and how often they kill deer,” Allen said. “When a bear pushes a puma away from a carcass, run the puma is gone, and the bear eats the deer. The puma then has to make another kill to get the energy it needs. “
Without black bears, puma killed about once a week, Allen said.
“But in the presence of bears, they kill every five to six days,” he said. “They have to work harder, and they’re getting less nutrition overall.”
Pumas in populated areas kill more and eat less
Maximilian L. Allen et al, The competition cannot be tolerated: An energetic loss from kleptoparasitism by a dominant scavenger can alter the apex predator’s hunting behavior, Basic and applied ecology (2021). DOI: 10.1016 / j.baae.2021.01.011
Presented by the University of Illinois at Urbana-Champaign
Citation: Study: Black bears eating pumas lunch (2021, March 19) retrieved March 19, 2021 from https://phys.org/news/2021-03-black-pumas-lunch.html
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