Burrowing Owls Once Made Alameda their Home
Burrowing Owls Once Made Alameda their Home
The burrowing owl is a longlegged small owl that lives in burrows usually created by other animals. They use rip-rap and at the Alameda Wildlife Refuge (AWR) they also use sinkholes in the tarmac of the former Naval Air Field. Ground squirrels are a common source for their homes. Owls will “groom” these burrows, dirt flying out of the hole with comical flare up to 6 feet from the entrance before occupying them.
The owl has a flattened facial disc, but also shows exaggerated white eye-brows and “chin” which are used as a defensive display when excited and sometimes accompanied by wide open eyes and standing tall while bobbing.
Both males and females are brownish and cream colored with barred breasts and white spotting on brownish backs. I have seen feathering around eyes that may protect from dirt and sand in their burrows. The difference between sexes is subtle and not entirely easy to determine. Juveniles have light cream-colored breasts lacking the brown barring. Adult length is 7.5 -11.0 inches and wingspan from 20 to 24 inches. Weight is 4.9-8.5 ounces.
These owls eat small mammals and insects but will take lizards and other small prey including birds. Active during the day, they hunt primarily at night. Methods vary from waiting for prey with a surprise attack, catching some insects in flight, digging for insects (earwigs are a favorite snack), and chasing prey using their long legs to run them down.
The first time I saw an owl chase an endangered least tern in the dark, it moved so fast through the spotlight that I was sure the blur was a cat. Later I read that the London Zoo had burrowing owl races. Those long legs have purpose!
The burrowing owl has many vocalizations. That it can mimic a rattle snake is a handy defense against predators digging into Rick Lewis This burrowing owl family calls the Central Valley home. Families of owls like these once lived in Alameda. Burrowing Owls Once Made Alameda their Home Alameda Wildlife their burrows. Another interesting behavior is their placing animal scat at the burrow entrance. It is thought that cow manure, dog or other fecal deposits attract insects to the front door, a wildlife version of “home delivery”.
There was a time, not long ago, when burrowing owls were commonplace in Alameda and the adjacent Oakland Airport. They perched on fences at dusk and prompted my young son to want to count them. We had as many as 40 making the rounds of fences and open grasslands. They nested here with their large families of 6 to 10 young on display outside burrows in late spring.
Today, with breeding owls near absent, we are left with migrants that come specifically to AWR to winter. We begin to look for them in late September and are somewhat relieved to see them depart in late March, a month before least terns arrive. These appealing owls, also listed as a “California species of special concern,” are serious predators to least terns.
In 2006 an offsite breeding pair caused a near complete failed breeding season for Alameda’s iconic tern. This owl will hunt young and adult terns, easy prey as terns are confused in darkness. They stash what isn’t immediately eaten in their burrows.
We counted 11 migrants during December AWR surveys in 2018. It seemed a remarkable number seeking out winter residence here. We’ve never seen banded migrants so can’t be sure from where they come or how far they travel. We consider this number underestimated given how difficult they are to locate.
Often specific burrows are occupied winter after winter which helps in finding them. Returning birds appear to recognize our vehicle, showing no concern when we approach. Others flush from a distance and bob with agitation showing the white brow and chin.
Threats to burrowing owls are numerous. Their low flight makes them vulnerable to vehicular strikes as they cross roads. Both cats and dogs are known to be a significant threat. Habitat loss is a primary issue, and poisons put out for rodents ironically cause a secondary poisoning to effective predators. They are victims to other birds of prey.
I’ve witnessed them carried away by both Red-tailed Hawk and Great-horned Owl. With care and monitoring we hope the Alameda burrowing owls will always find habitat here. I so wish Alameda children could know the pleasure of counting little owls again. Leora Feeney is a member of the Golden Gate Audubon Society and the Chair of the Alameda conservation committee, the Friends of the Alameda Wildlife Reserve. To learn more about birds, go to www.goldengateaudubon.org