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San Diego Zoo Conservation Project Uses Squirrels to Help Owls

  • Burrowing Owl
  • Burrowing Owl
  • California ground squirrel released in San Diego
  • California ground squirrel
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This month, the San Diego Zoo Institute for Conservation Research announced that they've released over 350 squirrels to the wild as part of a long-term focus on rejuvenating the numbers and habitat of the burrowing owl. Visiting parts of San Diego county designated as burrowing owl stomping grounds (including Otay Mesa and Jamul), releasing squirrels is helpful to the owls in a number of unique ways. 

The California ground squirrel is one of the most common in America, and can be found predominately on the west North American coast, from Mexico to Washington. While they're often scampering in trees, they spend a majority of their time within 25 feet of their underground burrow. And, they're smart as well. In 2006, researchers at UC Davis discovered that female squirrels have learned to chew on rattlesnake skin, and then lick their fur and their squirrel pups in order to disguise themselves to local snakes, which hunt by scent.

So how do these squirrels help out burrowing owls? While they've become common park scavengers in urban environments, each squirrel will burrow its own area, which when vacated serve as homes to burrowing owls. Unlike typical owls, burrowing owls will spend their active time during daylight, mostly hunting in the dawn and dusk hours.  "Burrowing owls are a species of special concern in California; they're a very important part of the grassland ecosystem," said Colleen Lenihan, Ph.D and Postdoctoral Associate at the Zoo's Institute for Conservation Research. "They live underground in association with ground-dwelling mammals like the California ground squirrel. They eat a lot of rodents, small birds and quite a few insects." They're also known to eat fruits and seeds, another rare trait for owls. Aside from pre-built burrows, additional help from squirrel neighbors comes with their appetite, which keeps the surrounding grass and invasive plant species down enough for burrowing owls to hunt. And, it just seems like having an active squirrel area fosters more life in general, as, according to the ICR, locations "...with ground squirrel colonies have a greater diversity of reptiles, amphibians, insects and birds than sites where they are absent."

The burrowing owl is currently listed as a species of concern by the U.S. Fish and Wildlife Service, likely because its atypical habitat areas are being taken away for human expansion. California scientists from the ICR have formed a team with San Diego State University, the U.S. Fish and Wildlife Service and the California Department of Fish and Game on this conservation project that will ultimately cost about $240k for the first year, paid via grants and the San Diego Zoo. It will be determined next year if the squirrel introduction has created functional ecosystems for burrowing owls, and the decision to stop or extend the project will be made at that time.