Tag Archives: biological control

Life of famous California mountain lion sheds light on the dangers humans pose to wildlife, and points to a better way forward.

In December of 2022 the famed Los Angeles mountain lion P-22 was euthanized, following a storied life of urban danger, carnage and mayhem. Much can be said of him; Notably the admiration and pride he inspired in Angelinos and native people who could identify with his will to survive true to his nature, in a world that essentially denies that. Laid to rest in a private tribal ceremony, this mountain lion has become an elder, a teacher, a cautionary tale. Here’s more on the remarkable life of a celebrity mountain lion.

It is known that P-22 survived at least one collision with a motor vehicle. He suffered illnesses related to constant proximity to humans and their chemical counterparts. Rodenticides played a role in his illnesses. The first- and second-generation types of anti-coagulant poisons commonly used today sicken and kill many non-target predators and carrion eaters, including raptors and pets.

P-22 was repeatedly poisoned by rodenticides that sickened him, leading to secondary infections such as mange. See this list of commonly sold rat poisons that you should try to avoid, because of the danger to non-target species!

Audubon Society and the Bio Integral Resource Center‘s Guide: Protecting Raptors from Rodenticides (Common Sense Pest Control Quarterly Special Issue 2011, Published January 2013) offers important insights on how we can take measures and enlist nature’s help to safely reduce rodent populations. It is important to establish an integrated approach, utilizing all available least toxic methods. Innovations such as birth control are being developed to control rats. An example of Biological Control is when we encourage our friends of the forest to feast on rodents by providing improved habitat such as perches and nest boxes. Combining and coordinating multiple approaches is the key to effective Integrated Pest Management.

While a lot is mentioned of secondary poisonings such as occurred with P-22 who suffered years of sub-lethal effects from eating poisoned prey, primary poisonings also exact a cost to non-target species. Primary poisonings occur when an animal directly ingests poison baits. They are designed for palatability, so pets and many other non-target animals can easily be poisoned if allowed access. Non-target species may include woodmice, field voles, bank voles and even insectivorous birds!

Much of this information comes from the BIRC publication: Protecting Raptors from Rodenticides which can be purchased from BIRC at this link: The Integrated Pest Management Specialists. Please support this important non-profit that promotes ecologically sound approaches for reducing pesticide use and protecting our environment.

Best Practices for dealing with a Rat Infestation

• Address any sanitation gaps and secure all trash and food sources, indoors and outside.
• Regularly check for gaps where rats can gain entry -and seal them.
• Remove dense landscape plantings such as Ivy (Hedera ssp) that provide harborage and pathways and facilitate entry into dwellings and structures. Prune tree branches away from buildings to prevent wall and roof access.
• Use trapping methods to reduce populations (An entire course could be taught on this.)
• Least Toxic Method: RatX uses a bait approach, but the lethal mode of action is dehydration from corn gluten, not chemical poisoning; thus eliminating the possibility of secondary poisonings.
• If using professional abatement services, ask about least toxic options such as RatX and birth control baits such as Contrapest (currently only available through licensing agreement)
• Use conventional rat baits only as a last resort if trapping and other methods fail. (First generation rat baits such as warfarin are less toxic to non target species than second generation rat baits such as bromethalin and Vitamin D-3)
• Always use exclusion measures to avoid accidental poisonings, and check bait stations often.
• Regularly monitor for rats and check for re-colonization. Keep awake to new methods.
• Establish perches and nest boxes to encourage raptors appropriate to your area.
• Build a Barn Owl Nest Box
• Build a Kestrel or Screech Owl Nest Box
• How to Attract Raptors

Special thanks to Ron Whitehurst of Rincon Vitova Insectaries for the info about RatX!

Can you add to this list? Thoughts to share about P-22? I’d love to hear from you!