2006-10-20 / Community
Cougars struggle to survive in local urban areas
National Park Service biologists tracking eight local cougars say five of them have died.
One factor they blame is the use of rat poisons containing anticoagulants.
Mountain lions ingest the toxin by preying on coyotes that have eaten poisoned rodents, said Ventura County Supervisor Linda Parks. Parks has encouraged the county park department to stop using pest control formulas that contain anticoagulants.
A young pair of lions designated P3 and P4 lived in the hills around Simi Valley and Moorpark between 2003 and 2004 and died within two weeks of each other from internal bleeding caused by anticoagulant used in rat poison, said biologists. The poison was believed to have originated in small mammals eaten by the cougars.
Small cuts and scrapes can become serious when blood doesn't clot, and that is apparently how the cats died, said Raymond Sauvajot, chief of planning, science and resource management for the Santa Monica Mountains Recreation Area.
Local park officials have been studying a family of cougars in the rugged 250-square-mile recreation area.
The dominant male, P1, is 9 years old. He weighs about 140 pounds and in 2002 was tagged with a transmitter collar so that biologists could track his whereabouts.
P1 mated with P2, the only female known to live in the area. She produced four healthy kittens in July of last year. The male killed the adult female earlier this year. P2 was in heat and probably acting to protect her kittens, which were nearby, said Woody Smeck, superintendent of the Santa Monica Mountains National Recreation Area. She died from wounds to her head.
A necropsy also showed the presence of anticoagulant in the cat's liver, but the level was not high enough to cause death, said the biologists.
About three months ago, P1 killed again. This time the target was P6, one of the young cats sired by P1. Biologists aren't entirely sure why P1 killed the 15monthold lioness; males usually share territory with females. But since males don't help raise their kittens, P1 probably didn't recognize P6 as his offspring. "It's possible that P1 was attempting to mate and the encounter turned fatal," Smeck said. P6 died from fatal puncture wounds. Anticoagulant traces were also found in her liver.
Most recently, the dominant male killed another one of his kittens when he crossed paths with the young male, P5, in Point Mugu State Park.
Biologists suspect the older male was defending his territory. Lethal puncture wounds were found on P5's head.
The two surviving juveniles, P7, a female that occupies a stretch of rocky terrain just south of Hidden Valley, and P8, a male that lives in the Topanga Canyon to 405 Freeway vicinity, are both about 16 months old and they're primarily feeding on mule deer.
For now, P8 is staying away from P1's territory in the eastern portions of the territory but there is some overlap and park officials expect that an encounter between the two is likely at some point.
But P1 is now quite old and another male will eventually replace him, said Smeck.
Room to roam
Despite the grim recent history of the local cougar family, park officials are still cautiously optimistic that mountain lions can persist in the Santa Monica Mountains provided connecting corridors are preserved.
While there may be "opportunity crossings" along the 101 Freeway, the Liberty Canyon wildlife corridor in Agoura Hills is the best avenue for animals heading north.
Segments of open space in the Santa Susana Mountains have also been identified as critical pathways.
NPS biologists have tracked a variety of mammals moving across the freeway using the Liberty Canyon underpass and they hope P8 will do the same, safely avoiding the dominant P1.
Liberty Canyon is the last best option for connectivity in the central Santa Monica Mountains, but another good option exists in the western Santa Monicas along the Conejo Grade, Sauvajot said.
Cougars need habitat connectivity to survive, he said. There's simply not enough space in the local mountains to support a viable mountain lion population over the long term. The mountains must be connected by pathways to habitats to the north.
But if lions continue to behave "naturally," eating deer and staying away from people, they are reproducing, and they can find and use movement corridors near developments and across roads to disperse through the challenging landscape, they will survive, Sauvajot said.
"We don't have information on locations of lions in the Simi Hills or Santa Susana Mountains, but it is very likely that lions are present in those areas," Smeck said.
There could also be other males in the vicinity of the young female in the Santa Monica Mountains, but biologists have not found tracks or evidence to date, they said.
"Mountain lions are an important part of the ecology of our nearby hills," said Smeck.
They occupy the top of the food web and they help to maintain the ecological balance. Cougars' primary prey is mule deer but they are also known to eat coyotes, raccoons and other small animals.
Cougars hunt at night and rarely move around during the day. But when the hunt is successful and they eat their prey, lions also may get a dose of rat poison, which can be lethal.
Residents are the largest users of anticoagulant poisons (such as D-Con, which has bromadiolone and brodifacoum anticoagulants) and some public agencies still use them. Parks is working to prohibit the use of such products.
Other pest control measures are available, including gas and traps, that do not contain anticoagulants.