Pumas kill more and eat less when humans are near, study shows

Chuck Bednar for redOrbit.com – Your Universe Online

Prominent carnivores such as female pumas to increase the amount of prey that they kill but decrease the amount that they consume when they encounter homes, roads, and other indicators of human development in their territory, a new study has discovered.

Writing in a recent edition of the journal Proceedings of the Royal Society B, University of California, Santa Cruz Ph. D. student Justine A. Smith and her colleagues explained that the increased kill rate and decreased consumption rate is a response to human-induced fear.

“We investigated how higher housing densities influenced puma behavior at kills and how often they killed,” Smith, an environmental studies student, said in a statement Thursday. “We found that female pumas spent less time feeding at kill sites as housing increases.”

The phenomenon can have an impact on both the deer population, as well as the pumas’ own breeding success, Smith and co-authors Yiwei Wang and Christopher C. Wilmers, an associate professor of environmental studies, noted. They found that females killed 36 percent more deer per year in developed areas than in those where there is little to no housing.

“Increased kill rates may lead carnivores to waste energy and also influence prey survival rates in human-modified landscapes,” said Smith, who along with her co-authors is part of the Santa Cruz Puma Project. “We concluded that food loss and high energy costs due to human avoidance at kill sites is compensated for by increasing kill rates.”

During the course of their study, the researchers studied the behavior of 30 animals that had been captured, outfitted with GPS monitoring collars, and released. Thanks to the collars, Smith and her colleagues could keep track of the location and travels of the pumas, as well specific hunting-type behaviors such as bursts of speeds or pounces.

They discovered that the hunting habits of pumas were most affected when their territories were located within 150 meters of human development. Furthermore, they found that females had less of a range than males but had higher kill rates. In fact, the female pumas killed an average of 67 deer per year, compared to just 44 for males who covered roughly three times more ground.

“We observed strong behavioral responses by female pumas to human development, whereby their fidelity to kill sites and overall consumption time of prey declined with increasing housing density by 36 and 42 percent, respectively,” the authors wrote. “Females responded to this decline in prey consumption time by increasing the number of deer they killed in high housing density areas by 36 percent over what they killed in areas with little residential development.”

“The loss of food from declines in prey consumption time paired with increases in energetic costs associated with killing more prey may have consequences for puma populations, particularly with regard to reproductive success,” they added. “In light of the extensive and growing impact of habitat modification, our study emphasizes that knowledge of the indirect effects of human activity on animal behavior is a necessary component in understanding anthropogenic impacts on community dynamics and food web function.”

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