Illegal pot farms in California is poisoning rare and endangered owls in the area!

The Northern spotted owl (Strix occidentalis caurina) is one of the three subspecies of spotted owls, and there are probably only a few thousand pairs left in the wild. Most owls are found in Oregon, but there are also around 500 owl pairs in Northern California. It is listed as threatened by the United States Fish and Wildlife Service, but there are luckily conservation efforts in place to try to take care of this rare subspecies of spotted owl.

A northern spotted owl (in a zoo). Image by Wikimedia Commons user Cacophony, posted with the Creative Commons Attribution-Share Alike 3.0 Unported license.

A newly published article in the journal Avian Conservation & Ecology captured owls in Northern California to check if they were contaminated with any poisons or not, and the results showed that 70 % of the Northern spotted owls were poisoned by anticoagulant rodenticides, a poison used to kill rats on farms. This rodenticide is documented to be stressful for owls and birds in general, and have even been documented to kill owls in the past.

What happens when the owls eat anticoagulant rodenticides is that they are unable to recycle the vitamin K in their bodies which could be fatal to all organisms that digest it.

During the experiment the researchers also tested the Barrel owl (Strix varia) for the same poisons, and found that 40 % of these were also contaminated by at least one anticoagulant rodenticide. This species is owl is however not threatened, but it was used since it competes with the Northern barrel owl for habitat and food, so the researchers wanted to collect samples from the species as well to get er better overview of the total number of affected owls. Since these owls are very much alike it is safe to assume that 40 % of both owl populations would be affected by the rodenticide, and the 70 % number they for for the Northern spotted owls might be too high because of a low sample size.

A barred owl. Image by D. Gordon E. Robertson, posted with the Creative Commons Attribution-Share Alike 3.0 Unported license.

The culprit is most likely marijuana growers

The area close to where the owls were sampled is known to be used by illegal marijuana growers, and it is well-known that this has many negative effects on the wildlife in the surrounding area. If you are growing illegal drugs you are obviously not going to care about the laws that apply to using pesticides in the area, which could very well prove to be fatal for the threatened Northern spotted owl.

The researchers behind the study have previously also researched the effects these marijuana farms have on the local wildlife, and told the LA times that the farmers would often leave food spiked with this rat poison on the borders of the farm in order to prevent herbivores from entering the farmlands.

Why the Northern spotted owl is threatened

The Northern spotted owl is very picky with its habitat, and prefers to live in or very close to old-growth forest. This type of forest is also called virgin forest, and it is very rare these days. The thing about this type of forest is that it must never have been logged, so it's not that strange that it has become very rare. The unique thing about the old-growth forest is that there is a mix between old, dead and young trees, which is rarely seen in forests that have been recently logged, and a forest might use as much as a thousand years to become old-growth forest after having been logged once.

An old growth forest. Notice dead trees alongside both young and old trees; a good indicator of old-growth forest. Image by Snežana Trifunović, posted with the Creative Commons Attribution-Share Alike 3.0 Unported license.

Old-growth forests have their own unique ecology, and we find many species here that would not be found anywhere else, especially fungi, lichens, mosses and insects, which in turn attracts some rare birds and mammals. Sadly most old-growth forest is already gone, but most countries have some protected old-growth forest left where you can find a lot of cool species.

Thanks for reading

Thanks for reading about how the rare Northern spotted owl gets poisoned by the illegal pot farmers in California. I hope you enjoyed to learn about this topic despite the fact that it's bad news. Sources for the different claims are posted in the text, so make sure to click on any of these to get more information!