Marijuana Growers in California Are Killing Owls and Disrupting the Food Web

Weed growers in California are killing owls but it doesn't have to be this way. FRED TANNEAU/AFP/Getty Images

Owls in California are dying near illegal black market marijuana fields, and scientists believe the plants, may be to blame. Some of the owls included in the study belong to endangered species, and according to researchers, these findings may suggest that one day buying owl-safe marijuana may become as important as dolphin-friendly tuna.

In a study now published online in the journal Avian Conservation and Ecology, researchers found carcasses of several owl species in northwestern California which had measurable amounts of anticoagulant poisons. The researchers believe the owls consumed the poison by eating rats that had been poisoned by rodenticide placed in marijuana fields by black market growers.

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For their research, scientists surveyed areas known to have unpermitted marijuana growth, often accompanying police during their investigations. A surprising amount of anticoagulants were found in the collected owl carcasses. This poison affects the blood's ability to properly clot which can result in internal bleeding, Live Science reported.

Seven of the 10 Northern spotted owls and 40 percent of the 84 barn owls collected tested positive for rat poison. What is particularly troubling is the fact that Northern spotted owls are listed as a threatened species under the federal and state Endangered Species Act.

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"We have visited only a very small fraction of these growths but there is still a percentage of them using rocinidice," lead study researchers Mourad Gabriel of UC Davis told Newsweek . According to Gabriel, he and his team are unaware of the magnitude of the problem but believe it goes further than the areas that they were able to investigate.

Under California law, it is illegal to use rodenticide during marijuana cultivation. Unfortunately, the growers involved in this research did not have permits, meaning that they were not exactly abiding by federal law. Gabriel expressed concern that the recent legalization of marijuana in California could mean that even more individuals may choose to grow the plants.

"We don't know the magnitude, but it brings us concern that so many growers still want to be in the black market, " said Gabriel. "What is restricting them from using this rodenticide? There needs to be more done."

There are alternative ways to grow marijuana that do not pose a threat to the ecosystem. YASSER AL-ZAYYAT/AFP/Getty Images

According to Gabriel, marijuana growers, in general, are not the problem, but rather too many growers not following the rules is. "We are not stating that each and every cultivator is placing rodenticide. We are saying that there is evidence that there is contamination of the food web that potentially comes from illegal growers," sad Gabriel.

However, the problem is not completely out of our hands. According to Gabriel, marijuana consumers can make conscious efforts to not purchase products from growers who do not have permits and therefore may not be following government protocol could potentially be putting wildlife at risk. Just as consumers make decisions to buy dolphin-safe tuna or clothing that is free from child labor, perhaps one day "owl-safe weed" may become a household product.