Rat Poison Found in Bobcat in Simi Valley Area

B-332 died on December 19, 2016, in Simi Valley. Residents in a neighborhood flanking the Simi Hills reported a mangy bobcat hanging around. Local animal control picked him up, euthanized him and, noting the research GPS collar, contacted and delivered the body to Joanne Moriarty, a wildlife ecologist for the National Park Service (NPS), who estimated he would likely have died within a day.

Necropsy results for Bobcat 332 are in and the findings are what biologists suspected. The three-year-old wild cat had anticoagulant rodenticide, commonly known as rat poison, in his system. Specifically, very high levels of the compound bromadiolone were found, in addition to brodifacoum, difethialone and diphacinone.

“Cases like this continue to tell us that household rat poison is penetrating the ecosystem with deadly consequences,” said Moriarty. “I hope B-332’s fate can inspire residents to look to alternative means for managing rat problems.” (nps.gov/samo/learn/management/rodenticides.htm)

Rat poison works its way up the food chain as it is consumed first by target animals or other rodents, and they are, in turn, eaten by predators. For example, poison in a rat eaten by a coyote, which is eaten by a mountain lion, will be found in all three species. Since 2002, rat poison has been found in 90 percent of bobcats analyzed as part of a long-running NPS study of bobcats in and around the Santa Monica Mountains.

California restricted the retail sale of second-generation anticoagulant rodenticides in 2014, but they are still available for use by licensed applicators. First-generation anticoagulant rodenticides are still widely available for purchase. Both first- and second-generation compounds were detected in B-332’s liver.

The connection between exposure to anticoagulant rodenticide and mange, a parasitic disease of the hair and skin, is still not fully understood. Previous NPS research has found that bobcats that have ingested rodenticide are much more likely to suffer from severe mange. (http://onlinelibrary.wiley.com/doi/10.2193/2005-61)

The prevalence of mange peaked between 2002 and 2006 in the Simi Hills area, during which time more than 50 percent of radio-collared bobcats died as a result of the condition, overtaking vehicular collisions as the leading cause of death among the local population. Although few cases were seen in the Simi Hills from 2008 until about 2013, more cases have been seen again in recent years.

B-332 was first captured in December 2015 in Westlake Village, on the southwest end of the Simi Hills. He traveled as far east as the City of Hidden Hills and the community of Bell Canyon, then moving northwest and eventually landing in the Simi Valley area when his GPS collar malfunctioned in May 2016.

Bobcats (Lynx rufus) are small, spotted cats that inhabit most of North America, including all of the United States, most of Mexico and southern Canada.

Since 1996, NPS has been studying carnivores—more than 340 bobcats, 145 coyotes and 50 mountain lions—in and around the Santa Monica Mountains to determine how they survive in an increasingly fragmented and urbanized environment.


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