Marijuana Growers Bringing Rat Poison to Remote Areas Are Likely Responsible for 70% of Endangered Northern Spotted Owls Being Exposed, Says Study Published Today
According to the study, “70% of Northern Spotted Owls and 40% of Barred Owls were exposed to one or more anticoagulant rodenticides.” (The Northern Spotted Owl is listed as endangered.)
The owls, and other wildlife, are believed to be exposed to the poison when they capture rats and other creatures which have eaten the rodenticides at the marijuana gardens. The rats are likely ill from the poison and thus slowed making them easier for the predators to capture and eat.
Anticoagulant rodenticides, rat poisons, make it difficult for wildlife to use vitamin K which can cause internal bleeding and lead to the death of the animal.
“Spotted owls are inclined to feed along forest edges. Because [marijuana] grow sites break apart these forest landscapes, they are likely source points for exposure,” said lead author
Mourad Gabriel has been involved in looking at the intersection of wildlife and poison from illegal marijuana gardens since he was studying fishers, a weasel-like local mammal that is rarely seen. Gabriel is a research faculty member with the UC Davis Karen C. Drayer Wildlife Health Center within the School of Veterinary Medicine’s One Health Institute. He’s also executive director of nonprofit Integral Ecology Research Center.
Gabriel and others are concerned that the number of illegal grows will continue to increase inside critical habitat for Northern Spotted Owls and that those unregulated growers will continue to bring rodenticides and other problematic chemicals into these remote areas further endangering this species and others.
“When you have thousands of unpermitted grows and only a handful of biologists that regulate that for multiple counties, we’re deeply concerned that there aren’t sufficient conservation protective measures in place,” Gabriel explained. “If no one is investigating the level at which private marijuana cultivators are placing chemicals out there, the fragmented forest landscapes created by these sites can serve as source points of exposure for owls and other wildlife.”
While owls were not killed for this study, according to a UC Davis press release, “Northern spotted owls were opportunistically collected when found dead in the field, while barred owl tissue samples were provided by outside investigators conducting an unrelated barred-owl project.
“Access to these owl specimens allows us to explore the health of the entire regional forest system,” says Jack Dumbacher, curator of Ornithology and Mammalogy at the California Academy of Sciences. “We’re using our collections to build a concrete scientific case for increased forest monitoring and species protection before it’s too late to intervene.”
According to the UC Davis Press release,
The necropsies for this study were conducted at the California Academy of Sciences and the California Animal Health and Food Safety Laboratory System, which is part of the UC Davis School of Veterinary Medicine.
Additional co-authoring institutions include Green Diamond Resource Company, Hoopa Valley Tribe and Humboldt State University.
The study was funded by the United States Fish and Wildlife Service, Arcata and Yreka California Field Offices.