The study published in the journal Avian Conservation and Ecology focused on owls in Northern California’s Humboldt, Mendocino and Del Norte counties, part of the so-called Emerald Triangle, where remote farms — many in old-growth forests — produce much of the marijuana grown for the U.S. black market.
Researchers from the University of California, Davis, and the California Academy of Sciences tested 10 northern spotted owls found dead in the region. Seven of the owls tested positive for rat poison, used by pot farmers to keep rodents away from their irrigation systems and crops.
The northern spotted owls are listed as threatened under state and federal endangered species acts.
Forty percent of another species, barred owls, also tested positive for the rat poison.
Tissue samples of