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More on Rodenticides in Parkland

On Nov 16, 2015

Photos of Western Gray Fox, P22 and P34 are courtesy of the National Park Service

While the City of Los Angeles grapples with phasing out all rodenticide use, these dangerous substances continue to find their way into Los Angeles parks. Friends of Griffith Park, along with other organizations, have spoken before packed City Council committee hearings looking into viable alternatives. Thus far, we’ve seen little progress on this issue. Yet rodenticides are continuing to wreck havoc and unfortunately wildlife is already challenged enough by the drought and habitat fragmentation!

You may have read that a young mountain lion — P34 — succumbed to rat poisoning near Malibu this past October. Also, a Western Gray Fox was found dead in the Santa Monica Mountains in September, and a necropsy found the cause of death appeared to be anticoagulant rodenticides, since there was internal bleeding with no apparent trauma.

We’re experiencing the same problems here in Griffith Park. Recently a dead Western Gray Squirrel, our native tree squirrel, was discovered near the Fern Dell area. At first glance it looked like road kill since it was on the side of Western Canyon Road. However, there were no visible signs of trauma.

Friends of Griffith Park recently funded a gray squirrel genetic study being conducted by CSULA graduate student, Chris DeMarco. Knowing that he could use some of the squirrel for its genetic material, the squirrel was collected with the permission of Park Rangers and shipped off to be sampled. Upon receipt of the material, Chris encouraged us to invest in an analysis for the presence of rodenticides by sending a liver tissue sample to UC Davis Veterinary laboratory. The results came back: positive for first generation rodenticide, Diphacinone.

Diphacinone has been the most frequently detected compound found in bobcat blood samples during past studies which involved about two hundred bobcats in the Santa Monica Mountains, including Griffith Park. It was also one of the two rodenticides compounds detected in P22 when he was found sickened in 2014. (He has since recovered).

While we cannot definitively say this Western Gray Squirrel’s cause of death was due to rodenticide poisoning, the presence in gray squirrels further enlightens us all to the serious nature of the unintentional poisoning of the wild. FoGP believes that elimination of the use of rodenticides needs to become a priority for Los Angeles City, Rec and Parks, and residents near any wildlife habitat areas.

This past July, environmental activists waited for a follow-up presentation at the Arts, Parks and River Committee on rodenticide use in city parks. To date, the committee agenda has not mentioned any findings, alternatives or when this topic might be presented, even though concerns of rodenticide use in the Park continue to grow among concerned citizens.

The clock is ticking. Wildlife in the Park continues to sicken and die from anticoagulant rodenticide poisoning.

Click here for more information on how rodenticides move up the food chain:

Some helpful tips to help reduce rodents around your home:

  • Don’t leave pet food and water outdoors, especially overnight. Store pet food supplies indoors in sealed containers.
  • Seal gaps around air vents to building sub-areas and attics and any other openings that penetrate exteriors. Use sweep seals under doors. A rat can squeeze through a hole the size of a quarter; a mouse through a hole smaller than a dime.
  • Don’t plant ivy, as it provides shelter and a food source for rodents, snails and slugs. Ivy on walls can form ladders to windows, attics and other interior spaces.
  • Keep compost piles as far away from structures as possible.
  • Keep grass trimmed.
  • If you have a bird feeder, use a squirrel guard at the base to keep rodents away. Always keep the ground area clean of bird seed.
  • Keep outdoor grills and cooking areas clean.
  • Keep firewood off the ground and as far away from structures as possible to mitigate shelter opportunities.
  • Use city-issued plastic trash bins. If the bin is cracked or missing a lid, contact the Department of Sanitation for a free replacement.
  • Clean up trash in garden areas to remove shelter for rodents.




  1. E

    cayenne pepper is good for bird feeders, birds can’t taste it and rodents hate it


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