I found this Barn Owl feather in the leaflitter by the nature center. The surrounding trees are Coast Live Oaks and some Holm Oaks further away.
Far distant view of bluebird.
Western Bluebird (Sialia mexicana) Native, migratory songbird in the Thrushes (Turdidae) family that is 18cm (7 inches) long. Adult male tail, upper parts and throat are deep blue. Breast sides and flanks are chestnut colored, and belly and undertail coverts are gray. Female is duller, brownish gray above, breast and flanks tinged with chestnut, throat is pale gray. Nests in holes in trees and also in nest boxes. Bluebirds are year round residents in local (Monterey County) oak woodlands. Several nesting boxes can be seen in Toro County Park (Monterey County, CA). Diet is mostly insects and berries. Often forages by perching fairly low and flying down to ground to capture insects, sometimes hovering briefly before pouncing. May catch insects in mid-air, or may seek them among foliage. Perches or flutters among branches to take berries.
Breeding: "The western bluebird nests in cavities or in nest boxes, competing with tree swallows, house sparrows, and European starlings for natural nesting locations. Because of the high level of competition, house sparrows often attack western bluebirds for their nests. The attacks are made both in groups or alone. Attacks by starlings can be reduced if the nesting box opening is kept to 1.5 in (38 mm) diameter to avoid takeover. Nest boxes come into effect when the species is limited and dying out due to the following predators: cats, raccoons, possums, and select birds of prey such as the Cooper's hawk. Ants, bees, earwigs, and wasps can crawl into the nesting boxes and damage the newborns. Western bluebirds are among the birds that nest in cavities, or holes in trees, or nest boxes. Their beaks are too weak and small to dig out their own holes, so they rely on woodpeckers to make their nest sites for them."
Ebird with species description, range map and sound recordings: https://ebird.org/species/wesblu/
The Cornell Lab (Birds in U.S. and Canada, includes Compare with Similiar Species) https://www.allaboutbirds.org/guide/Western_Bluebird/
Xeno-canto Bird songs, sound recordings, and species range map: https://xeno-canto.org/species/Sialia-mexicana
Audubon Guide to North American Birds https://www.audubon.org/field-guide/bird/western-bluebird
Monterey Birds, Don Roberson, 2nd ed. 2002, sponsored by Monterey Peninsula Audubon Society, p. 368.
National Geographic Field Guide to the Birds of North America, ed. Jon L. Dunn, 7th ed., 2017, pp. 408-409.
National Geographic Field Guide to the Birds of Western North America, ed. Jon L. Dunn, 2008, p. 310-311.
Merlin Bird ID (great app available for mobile devices) by The Cornell Lab (Bird ID help for 8,500+ species) https://merlin.allaboutbirds.org/
Comprehensive Feather I.D. tools and more: https://foundfeathers.org/resources/
Found Feathers (Worldwide): https://www.fws.gov/lab/featheratlas/idtool.php