Burrowing owl populations take a nosedive
By Felicia Alvarez | The Davis Enterprise | May 27, 2015
The wide-eyed feathered heads of burrowing owls that used to pop out of ground tunnels across Yolo County are disappearing at an alarming rate.
Burrowing owl populations are a quarter of what they were in 2007, with habitat loss and other factors to blame, according to a census released Saturday. Conducted by the Woodland-based Burrowing Owl Preservation Society, the survey was conducted over 3,250 square kilometers of land throughout Yolo County.
These tiny owls are known for nesting in the burrows of squirrels, ferrets and other tunneling creatures. At the same time, the birds require infrastructure with height, as they use perches to hunt for rodents and insects from above.
The habitats they prefer can be strange at times. One volunteer recalled finding a nest of owls amid a pile of debris left in a farmer’s driveway. Another volunteer observed a nest in burrows near a cattle stable, where livestock were constantly being transported to and fro.
Burrowing owls have dotted California fields and hills for centuries. An account from the 1860s says “burrowing owls stood on every little knoll” in the state.
Today there are only 15 nesting pairs of these owls in Yolo County, said Catherine Portman, president of the Burrowing Owl Preservation Society. That is down sharply from the 63 Yolo pairs that were counted in 2007 in the Institute for Bird Populations’ statewide survey.
Although the species isn’t listed as threatened or endangered on a federal level, is it considered a “species of special concern” by state standards.
In a grassroots effort for owl conservation, more than 50 society volunteers took to the field last summer with only a pair of binoculars, a GPS system and landowner maps in hand.
Each volunteer was given a 5K-by-5K block of land to survey, out of an inventory of blocks including areas where the owls had previously been sighted and new, un-surveyed blocks. Despite a combined 651 hours of survey work, many volunteers went home with blank maps, empty of any owl sightings.
“The biggest population is densely in Davis,” Portman said.
For many years, dozens of burrowing owls found refuge at and near the Wildhorse Golf Course. Walnut trees at the golf course attracted squirrels that would dig tunnels that burrowing owls would seize to build nests. At the same time, the golf course borders agricultural land on which the owls could hunt.
Today, none of these nesting pairs remain, Portman said.
While a recent sewer project installed in the area may be a culprit, Portman said she’s not sure if this is the main reason the birds disappeared. Predators — such as coyotes and weasels — and changes in land use, vegetation and the owl’s prey base also may be to blame, she explained
Portman and other volunteers theorized that habitat destruction may be the biggest culprit.
Upon arriving at his survey plot, volunteer Jack Holmes was surprised at how empty the land was.
“There was no place to burrow, no hedgerows, nowhere to perch and forage,” he said. “The land was plowed down right up to the crop with nothing between each field.”
Agricultural trends of replacing row crops with orchards may be another source of habitat destruction, Portman said.
Other volunteers speculated that the birds may be moving on to a different territory, despite their known instincts to return to their birthplace.
Portman pointed to the Habitat Conservation Plan/Natural Community Conservation Plan that is being drafted in Yolo County as one possible solution. Burrowing owls are one of 12 species covered by the plan, which intends to set aside land easements for endangered wildlife. Under the plan, burrowing owls are set to receive at least 679 acres of reserve land.
The conservation plan has been in the works since 2004, and is in its second draft. After a public review period, the final plan is expected to be implemented in July 2017.
— Reach Felicia Alvarez at firstname.lastname@example.org or 530-747-8052.
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