if you can chop down trees in your yard the birds may be roosting in, this may discourage them from favoring your house. Otherwise, there is little I can suggest. The conditions favorable for these birds are inherent in the landscaping commonly used in California. Without a wholesale change in society's patterns of land use, there is no more chance of eliminating these birds than there is of eliminating termites, fleas, or flies.
Hummingbirds may gather, sometimes by the dozens, at concentrated sources of food such as flowering trees or a large number of hummingbird feeders. But they never flock in the sense of a group of birds moving as a cohesive unit.
Sorry, there is nothing to be done short of leveling your neighborhood of all trees and shrubs. If the habitat is suitable, mockingbirds will use it. And the landscaping typical of residential neighborhoods in southern California is ideal for mockingbirds. The Museum cannot advise you to violate the Migratory Bird Treaty Act, which protects all native birds of North America. According to the Act, all native birds are "migratory birds," whether they migrate or not.
Cliff Swallows use mud to build gourd-shaped nests. They seek vertical surfaces that are sheltered from above. So under the eaves of houses are ideal sites for them. We can only recommend that you try to exclude them from problem places before they arrive in spring (usually early March) by blocking the space under the eaves with a screen. The Museum cannot advise you to violate the Migratory Bird Treaty Act, which protects all native birds of North America. Consider tolerating these valuable consumers of flying insects. The San Diego County Bird Atlas revealed that the Cliff Swallow is already decreasing in our area.
Yes, both these species have increased since the 1980s. The crow in particular has spread its range into metropolitan San Diego, where it was absent before about 1985. San Diego is right at the southern edge of the crow's normal range. The raven always occurred here but has increased. Both species feed readily on urban refuse, so the growth of the city has increased their food supply. Crows nest in dense-foliaged trees (few in San Diego before urbanization); ravens nest on buildings, bridges, and other structures as well as in trees. The crow is smaller, with a higher-pitched "caw" and square-tipped tail; the raven is larger, with a deeper croak and longer wedge-tipped tail.
The Hooded Oriole is an ingenious engineer. It strips the fibers from the leaves of the Washingtonia fan palms commonly used for landscaping. By sewing the nest to the underside of the leaves it gives its nest both shade and protection from the rain. The male is strikingly colored in yellow-orange and black; the female is mostly yellow-green. Hooded Orioles are migratory, arriving in March or very late February, departing in late August and early September. They feed on both insects and flower nectar.
Unfortunately, smuggling parrots out of Mexico is a big business. Probably birds released by or escaped from smugglers have joined with birds escaped from cages north of the border. Some species of parrots are seriously threatened by destruction of their native forest habitat simultaneously with trapping of the young for cage birds. Several species may be seen around San Diego: the Red-crowned Parrot or Amazon, native to northeastern Mexico; the Lilac-crowned Parrot or Amazon, native to western Mexico; the Yellow-headed Parrot or Amazon, native to Mexico and Central America; the Blue-headed Parakeet or Conure, native to South America; the Mitred Parakeet or Conure, native to South America; and the Green Parakeet or Conure, native to Mexico. Other species are possible, and more than one species may flock together. Parrots are difficult to identify in the wild; most species are largely green. An exact description of the wing and head pattern is essential for identification.
These are Bushtits, the smallest birds in California except for hummingbirds. They are very social, living in flocks all year except when nesting. They are easily recognized by their high-pitched twittering call; when a predator approaches, the whole flock begins calling, in an attempt to confuse the predator and prevent it from singling out one individual for attack. Their nest is unique, a large bag of soft material with a roof and entrance on the side near the top. Bushtits feed entirely on minute insects. The males and females look identical except for eye color: males have dark eyes, females light eyes.