Active during the day, burrowing owls are usually seen guarding the entrance to their burrows. Burrowing owls use previously excavated burrows of ground squirrels for their home. Loss of habitat due to agricultural conversion and urban expansion is the major factor for the owl's decline and listing as a Species of Special Concern under the California Endangered Species Act. To encourage nesting, artificial burrows were installed at Sunnyvale Baylands Park.