How Fake Calls and Paint Splatters Help Owls Relocate

At one time, the Western burrowing owl was nearly everywhere in California. But the tiny chocolate-colored birds have been forced to leave their habitat because of continued development.

Unlike other owls that are nocturnal and live in trees, burrowing owls make their nests underground. They usually take over the abandoned burrows of prairie dogs, ground squirrels, and other rodents, and they can be active both in the daytime and at night.

Burrowing owls are protected by the Migratory Bird Treaty Act in the U.S. and Mexico. They are classified as a species of least concern by the International Union for the Conservation of Nature (IUCN) with their population decreasing. They are listed as endangered in Canada, threatened in Mexico, and are considered a “bird of conservation concern” by the U.S. Fish and Wildlife Service in several regions.

The two subspecies of burrowing owl in North America are the Western burrowing owl (Athene cunicularia hypugaea) and the Florida burrowing owl (Athene cunicularia floridana). Western burrowing owls are about 7-10 inches (18-25 centimeters) tall and weigh around 5.3 ounces (~150 grams).

As humans keep building, the construction causes these burrows to collapse and the owls have to set out on their own, trying to find a new place to live. According to the Center for Biological Diversity, the number of Western burrowing owls' breeding colonies throughout California dropped nearly 60% from the 1980s to the early 1990s, and by 2003, nearly all the owls had disappeared from the coast.

Often conservationists will use a technique called translocation to physically move the owls someplace else. But until recently, there has been little evidence that packing up the birds and moving them is successful.

Clever Trickery

In a new study, researchers used a bit of clever trickery to convince the owls to settle in at their new digs. Researchers at the San Diego Zoo Wildlife Alliance worked with the U.S. Fish and Wildlife Service, starting with owls on land that was about to be razed.

They installed one-way doors on their burrow entrances so the birds could not return after they left. Once they knew all the birds were gone, they collapsed the burrows. Then they translocated 47 owls and let them acclimate to a new area with new burrows in a special enclosure.

“We know this species likes to live close to other owls. If they are released in areas without them, they might leave in search of another area with resident owls. But that search may be unfruitful as the species continues to decline,” Dr. Ron Swaisgood, director of recovery ecology at San Diego Zoo Wildlife Alliance and senior author of the study, said in a statement.

“We wanted to find a way to trick the owls into believing other owls were living in the area to increase the chances they would settle there.”

For 30 days, while the owls were getting comfortable in the enclosure, the researchers played recordings of other Western burrowing owls in hopes of fooling them that there were already other owls in the area.

They also splashed nontoxic white paint onto the entrance of the burrows to make it look like bird droppings. They hoped that it would look like other owls had lived there and the area was safe for them.

Researchers fitted about 20 owls with GPS transmitters so they could track them and figure out where they were going. Some left right away, while the birds that had been fooled with the recorded calls and white paint settled in and made their homes nearby.

The results were published in the journal Animal Conservation.

“The results were remarkable! The owls were 20 times more likely to stay and make a home in the new location when these acoustic and visual cues were used,” said Swaisgood.

“With this discovery, we now have new methods that can be used to minimize the impacts of development and successfully establish owls in safe, protected areas. Our goal was not to stop development, some of which was necessary to develop renewable energy to tackle climate change, but find a win-win solution for owls, people and the environment.” 

Correction—February 15, 2022: This article has been corrected after a previous version included the incorrect weight of a burrowing owl.

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