The ground squirrels and squirrel holes in Berkeley's Cesar Chavez Park—many next to the trails— are hard to miss. Some holes are abandoned by squirrels, but are used by burrowing owls (Speotyto cunicularia) as resting place. These owls are known to dig burrow nest in open fields, but take advantage if they find some ready-made nests. I am not aware of any predator-prey relationship between squirrels and owls and assume that the burrowing owls feel well-protected here. According to a posted information sheet, burrowing owls hunt and eat crickets, beetles, small rodents, lizards, and crayfish. Since burrowing owls are active during night and day they can easily be watched during the day: These small brown birds (8 to 10 inches tall) are spotted with white. There head is rounded and lacks ear tufts. While you are watching them, they probably watch you with their yellow eyes.
Also see Burrowing owls in the northwest corner of Berkeley's Cesar Chavez Park.