April 19, 2013
Researchers Track Mountain Lions In California To Reveal Impact Of Human Development
[ Watch the Video: Mountain Lion Habitat Fragmentation Study ]
April Flowers for redOrbit.com - Your Universe OnlineFor three years, University of California, Santa Cruz (UCSC) researchers have been tracking mountain lions through the Santa Cruz Mountains to document how human development affects the predators' habits.
UCSC associate professor of environmental studies Chris Wilmers and colleagues at the UC Santa Cruz Puma Project reported the findings of their study in the online journal PLOS ONE. They describe three years of tracking 20 lions over 6,600 square miles. The aim of the project is to understand how habitat fragmentation influences the physiology, behavior, ecology, and conservation of pumas in the Santa Cruz Mountains.
"Depending on their behavior, animals respond very differently to human development," Wilmers said. Lions are "totally willing to brave rural neighborhoods, but when it comes to reproductive behavior and denning they need more seclusion."
When living relatively close to a metropolitan area, the large predators need a buffer from human development at least four times larger for breeding behaviors than for activities such as feeding or moving.
"In addition, pumas give a wider berth to types of human development that provide a more consistent source of human interface," such as neighborhoods, the authors write. The cats do not avoid places where the human presence is more intermittent, such as major roads or highways, with nearly the same fervor.
To date, Wilmers' team and a dog tracking team working with the California Department of Fish and Wildlife have captured 37 mountain lions. Between 2008 and 2011, twenty of those were closely followed — 12 females and eight males. As each lion was captured and anesthetized, the team determined his or her sex, weighed and measured the animal. The lions were then fit with an ear tag and a collar outfitted with a GPS transmitter, developed in part by an interdisciplinary team at UCSC, including wildlife biologists and engineers. The collars transmit location data back to the team every four hours. This allows the scientists to track the lions' movements and calculate locations of feeding sites, communication locations, and dens.
Mountain lions communicate with scent markings known as scrapes. Males typically make the scrapes by scraping leaves or duff into a pile and urinating on it to advertising their presence and availability. Females visit these sites when looking for mates. The project team set up remote cameras at 44 scrape sites, documenting males and females, to confirm GPS data from the pumas' collars.
The team identified 10 den sites belonging to 10 different female lions, and visited 244 "GPS clusters" where activities suggested a feeding site. They also found prey remains at 115 sites.
The collected data is helping to identify corridors where the lions travel between areas of high-quality habitat, including neighborhoods where females often are willing to explore for food for their litters.
Human interaction has resulted in lion casualties from automobile accidents or livestock raiding incidents. One male, 16M, was shown to have crossed Highway 17 between Scotts Valley and Los Gatos 31 times. 16M was hit and badly injured crossing the highway in November 2010. He was recently killed while attacking goats. 18F, a female who may have been 16m's mate, was killed in 2011 crossing Highway 17.
11 pumas died during the study, including eight that were killed attacking domestic livestock. The team advised livestock owners to consider keeping them in a "fully enclosed mountain lion-proof structure." They also advised people to be cautious in any known mountain lion roaming grounds. Wilmers said humans do not need to panic, however, about the presence of mountain lions.
The conservation goals of the study are meant to help lions survive in the midst of rapidly growing human development. They seek to fulfill this goal by building awareness of lions' behavior and providing safe transit opportunities under or over major highways.