Owl Housing Suggestions?

Barn Owls are great to have around as a natural control on rodents like rats, mice and squirrels. Like all nest boxes, success depends on the nest box being constructed and placed correctly. Barn Owls do like grassland to hunt in but they've found success in some places that would surprise you. They regularly used nest boxes towering over orchards along I-5 and in the rafters of barns and urban buildings. Unfortunately, not all Barn Owls are ready to nest in places that have that much activity. For example, the Moss Beach owls that nest at the Haute Enchilada restaurant are used to quite a bit of night-time activity but this is hardly the norm for Barn Owls. They prefer little activity during the day and they don't like any activity at night. Their nest boxes are often put in locations with so much activity that even a human wouldn't want to live there. In a place with lots of rodents, a Barn Owl may chance it and move in. But the habitat has to be right and predators like Great Horned Owls need to be relatively scarce.

owl housing? a tree? there's thousands of oak and eucalyptus trees around. SBCC has a big owl and hawk population that i enjoy almost daily....

No idea why no owls, Things to remember though:
Barn owls, as apposed to Great Horned Owls usually hunt from the air on excursions, not from the nest, so view/proximity to an open field is not required, or desired (they bring other predators). Barn owls range only about 1/2 a mile to a mile, so you need somewhat open land ( even a vacant lot) with rodent populations within a mile, which means pretty much everywhere in SB. Nest should obviously be hard for rats or cats or racoons etc. to access. Neither barn nor GHO care very much about being in the city as long as they have a nesting site and a place to hunt and nothing/no one is pestering them when they are trying to sleep. I know of at least two normally occupied Barn Owl nests in the Riviera/Mission canyon area, one. overhanging a road was occupied as recently as last Sunday. I have a relative in the middle of suburban Pasadena who has two Great Horned Owl's who perch all day in an oak tree about 10 feet over her garage for the last month and seem oblivious to the team of gardeners and their leaf blowers, which seem to bother them: not at all.
Santa Barbara offers a huge range of good nesting sites ( hollow oak trees, unused out-buildings, palm trees, etc), so it is probable that you just need to give it some time for yours to be discovered.

The Ojai Raptor Center is a wonderful resource. It may be that your environment is not suitable. Years ago, when we installed two owl boxes, complete with two pair of rescue barn owls, we were told that there was an 80% chance they would not stay. But it was still worth it, and though we never noticed owls in the boxes after the initial pairs left, we did see owls in nearby trees and told ourselves that they were 'ours'. And eliminating rodent poisons is a huge support to raptors. It baffles me that we have a perfect solution to rodents in raptors, yet we still seek to control them by eliminating their ideal predators.

We put up an owl house years ago. Facing north, hanging free, open access, view of the fields where gophers and rodents roamed. No luck. Eventually it was taken over by bees, however. They created a ton of honey and returned for a few years but eventually winds blew the house down. The bees did find a hollow tree nearby and swarmed there for a few years but the woodpeckers drove them out it seems. I rebuilt the owl house and put it in another place that was seemingly attractive but no luck. Occasionally I hear what I think is an owl. Not sure.

We have one of those defunct/unused Barn owl houses. We had high hopes when it was installed, but have since learned that Barn owls tend to nest where there are more open fields. Not gonna find that on Upper East/Lower Riviera/"urban" areas or the densely housed foothills.---------Great Horned owls prefer more wooded areas. ------- We have plenty of Barn owls making the rounds near our house; at certain times of the year, we hear them calling nearly every night. But putting up a Barn owl nesting box? It's likely an exercise in futility, unless you're near fields, marshes, farmland. Great Horned owls? We're not even gonna try for those. Our one neighbor has an affinity for massive light pollution. Like "Shall we play tennis tonight?" type backyard lighting. Her lighting shines into our yard, too. Owls hate lit up yards.

There's been one in my westside neighborhood lately. I just feel like there isn't enough open area for them to hunt successfully in most yards.

I get owl calls coming from my stone pine most nights but I have yet to see one. Maybe a brightly lit sign promising fast Wi-Fi and free HBO/Netflix?

We've lived in areas where owls thrive. Great Horned Owls like tall trees to perch and nest, with lots of open space, smaller owls may prefer dense foliage and medium trees, burrowing owls like rocky nooks on hillsides with a view. All have one thing in common, they enjoy a feast of mice, voles, gophers and other small prey such as lizards, beetles etc. Without a healthy buffet (which can occur in natural landscapes), and a water source (even swimming pools) they don't stay or return to an area. Ravens can drive them from nests also.

The ladies at the counter at La Cumbre Feed store are bird experts and can likely answer your question.

https://www.goodhousekeeping.com/home/gardening/a20705775/how-to-attract-owls/