Rat Poison Killed Glen Canyon’s Owl

This article has been republished from ForestKnolls.info as a caution to everyone interested in protecting our owls. They live in Sutro Forest, too. We hope and believe that UCSF does not use rodenticides in the Aldea Student Housing, but we expect that some people in the surrounding neighborhoods still do.

They probably don’t know they could be endangering other wildlife – like this beautiful owl.  [Edited to Add: There is more information about the actual poisons found in this owl HERE.]
Great horned owl in eucs (Photo: Janet Kessler)A few weeks ago, the Glen Park group had news of a Great Horned Owl found dead in Glen Canyon. There’s a well-known pair of owls that nest there every year, and typically raise two or three chicks. Neighbors fear this may be the male of that pair.

Of course people were upset, and they raised money for a necropsy – an autopsy for animals. This was conducted by Wildcare, a wonderful organization that rehabilitates injured wildlife. (I’ve written about them before, HERE.)

The result came in today. The owl died from eating poisoned rodents.

According the Wildcare press release,

“Commonly available rodenticides [rat poisons] are consumed by rodents, the basic food source for a number of different predators all the way up the food chain. These poisons kill by making whatever animal eats them bleed to death internally – slowly and painfully. While the poisoned animals – targeted or not – are still alive, they can be consumed by other predators. It is a terrifying prospect; to kill many animals while targeting only one.”

three owlets (Photo: Janet Kessler)A Great Horned Owl eats about 5 rodents a day, and much more if it’s feeding young. Its favorite prey is skunk, but it also eats rats and mice, rabbits, and birds. If someone poisons rats to get rid of them, they don’t die right away. Instead they wander around, increasingly weak and slow – and thus particularly attractive to predators. The poison can then kill the bird or animal that eats it – or even the next animal up the food chain.


We have Great Horned Owls in our neighborhood. I’ve seen them in Sutro Forest, up on the hillside, and in trees along Crestmont and Christopher. I’ve seen one on a lamp-post on Clarendon Avenue. We also have barn owls, which are even more vulnerable because they’re not large enough to eat skunks but eat more rats and mice instead. Every time we use rat poison, we’re endangering these birds.

Great Horned Owl in Mount Sutro Cloud Forest

Great Horned Owl in Mount Sutro Cloud Forest, San Francisco

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4 Responses to Rat Poison Killed Glen Canyon’s Owl

  1. Thanks for the post. Sad, but a good reminder that what we put in the environment stays in the environment.

  2. mareBear says:

    Thank you for posting this. I am sharing it with all my friends, as I love hearing the owls hoot at night, even in suburban peninsula.

  3. Pingback: How Did This Barn Owl Die? | San Francisco Forest Alliance

  4. Pingback: Rat Poison Killed the Glen Canyon Owl | San Francisco Forest Alliance

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