Cougar pair tracked by NPS killed by rodent poison

Two of the four cougars radio-collared by the National Park Service last year were found dead in December in the Simi Hills.

P-3, a young male whose range covered the Simi Hills and the Santa Susana Mountains, was found north of Oak Park. P-4, a young female who lived in the Santa Clarita Woodlands, but had crossed under the 118 Freeway in the last few weeks of her life, wandered south to Ahmanson Ranch and died west of Chatsworth.

Autopsies determined that both cougars died of internal bleeding from a buildup in their bodies of anti-coagulants, the active ingredients found in D-Con and other rodent poisons.

Scientists presume the cougars picked up the chemicals through the food chain, either by eating poisoned rodents directly or by eating predators that had fed on poisoned rodents.

The Park Service determined that both cougars preyed primarily on deer. However, they each also preyed on coyotes from time to time, and though deer are quite abundant in the cougars' territories, they could also have fed on rodents directly.

The Park Service has also been tracking bobcats and noted symptoms of anti-coagulant poisoning in many, as well as a general decline in bobcat populations.

Meanwhile, female cougar P-2, whose range covers the central Santa Monica Mountains, gave birth in August to four cubs-two males and two females, raising them in a cave high up in the mountains.

The Park Service put transmitters on each of the cubs and will monitor their movements in the coming months, as their mother teaches them the hunting skills they need to survive.

In light of what happened to P-3 and P-4, there is concern over the future of the cubs, particularly the males.

Since their presumed father, P-1, ranges throughout the Santa Monica Mountains from Point Mugu to Rustic Canyon, and male cougars are very territorial, the male cubs will probably need to find new territories elsewhere when they reach adulthood.

Since the Santa Monica Mountains are bordered by the urbanized San Fernando Valley and Los Angeles Basin on the east, the Oxnard Plain on the west, and the Pacific Ocean on the south, the only direction the young male cougars can go is north. There they will find their way blocked by the Ventura Freeway and the string of subdivisions and commercial complexes that line much of the area.

There are a few places where protected natural lands border the Ventura Freeway, but none of the Park Service's radio-collared cougars have yet crossed over or under it.

However, P-1 and P-2 have been tracked on hillsides overlooking the critical Liberty Canyon undercrossing of the freeway on a couple of occasions in the past year.

Even if the cubs manage to cross the Ventura Freeway, Park Service officials fear they may come across the same anti-coagulants that killed P-3 and P-4.