One of the questions I heard most often from park visitors watching the Burrowing Owls last winter was, “Why aren’t they using the area set aside for them?”
In fact, of the eight or ten Burrowing Owls that visited the park between October 2018 and March 2019, only one took up residence inside the fenced preserve on the northeast corner of the park. That owl stayed 90 per cent of the time out of sight on the rocky slope on the eastern shore, under a rough canopy of dried vegetation. It came out on the exposed plateau only on rare occasions, usually on days of heavy fog or rain, when traffic in the park was low.
All the other visiting owls perched on the north shore west of the fence, many yards “out of bounds,” in spots next to or surrounded by tall vegetation, typically the fennel that grows there abundantly.
The joking answer to the question why most owls avoided the fenced area is “The owls can’t read the posted signs.” But the owls are teaching us the serious answer by their choice of perching sites. They want to have the protection from overhead view that the nearness of tall vegetation provides.
In the fall of 2018, Parks staff undertook a radical clearing of the area inside the decorative fence intended as a Burrowing Owl preserve. Staff cut down all vegetation except a few isolated coyote bushes. The tall fennel that grew on the north side of the area, between the paved trail and the rocky slope to the water, fell victim to the clipper.
The intention behind this clearing was good. According to the books, Burrowing Owls prefer to breed in clear, flat or slightly sloped areas with good lines of sight in all directions. I believed it and repeated it myself. So what’s wrong with clear-cutting?
What’s wrong is that the owls don’t come here for breeding. They come here to wait out the winter in their northern breeding territories, where they return in spring. A habitat that works for them while breeding doesn’t necessarily work for them while wintering.
The owls have been teaching us that they want protection from overhead attack. Red-tailed Hawk, Northern Harrier, White-tailed Kite, Cooper’s Hawk and others were active in the park during the same season when the owls were present. Even though the owls are raptors also, they are so small by comparison that these bigger raptors will take them if they can.
The fennel is too fragile to serve as a perch for these heavy raptors. I saw hawks, kites, and harriers perching on bird boxes and trees many times, but never on fennel. However, the fennel’s umbrella-like flowers, even when dry and gone to seed, do a fair job as a visual screen from above.
Even where the owls breed, clearcut habitat is not necessarily required. “Suitable owl habitat may also include trees and shrubs if the canopy covers less than 30 percent of the ground surface,” according to a study by the California Burrowing Owl Consortium.
Some clearcutting has to be done here inside the fence, but it should be limited to the area enclosed by the outer paved trail. See red area in map below. I believe we will attract and retain more Burrowing Owls in the fenced area where we would like to see them if we left standing the tall vegetation on its north and east edges (green area in map). This will restore continuity between the preserve and the rest of the north shore, where most of the birds preferred to perch. The birds have taught us that they want some kind of overhead canopy on the water’s edge. The fennel is already coming back vigorously. Nature is generous in providing shelter for the Burrowing Owls, if only we don’t interfere.
The most recent Parks intervention in the area in late July has put it in perfect condition. The fennel on the outer perimeter is standing, and the weedy vegetation on the inside of the outer paved trail is mowed clear. If it is freshened up in late September in time for the owls’ expected arrival in early October, chances are good that the birds will adopt it as their preferred habitat for the winter season.
Then there’s the matter of the fence, decorative at best, but of little use as a protective barrier. But that’s an issue for another post.