Oak Titmouse (Baeolophus inornatus)

Distribution

Year-round range: From southwest Oregon through California to northwestern Baja California, Mexico.

Breeding habitat

Low- to mid- elevation habitats, closely tied to warm, dry oak or oak-pine woodlands. Composition of oak woodland varies, but arboreal species dominate, and woodland is generally open. May use scrub oaks or other brush as long as woodland occurs nearby. Despite clear preference for oaks, populations in some areas have adapted locally to warm, dry environments without oaks, e.g. western juniper woodland in extreme northern California.

Conservation status

This species is of moderate conservation importance, primarily because of its limited range and its association with intact oak and riparian forests. The overall population is exhibiting a significant long-term decline. Understanding precise habitat requirements and sensitivity to various land-use practices will be important for conserving future populations.

Description

Male: Generally described as “plain” and “drab”: brown-tinged overall, short crest, plain face. In some parts of range, birds are grayer and paler.

Female: Same as adult male.

Juvenile: Same as adults.

Vocalizations

Songs: Strong, whistled, repeated phrases tjiboo, or paired tuwituwi, and other variations. Also a rapid, popping trill.

Calls: Call high, thin notes followed by a single harsh scold si si si chrr; the same pattern often given in clear, whistled Notes pi pi pi peeew.

Foraging strategy

Primarily seen in trees at varying heights hanging from twigs and corrugations in bark to search undersides of limbs for insects. Captures insects by gleaning bark and, to lesser extent, foliage. Uses bill to expose arthropods by pecking and probing into crevices, chipping away bark, and pulling apart leaf galls, flowers, curled dead leaves, and lichens. Occasionally uses aerial foraging maneuvers (e.g., hovering, chasing) to attack flying insects. Large insects are carried held with foot and pulled into smaller portions using the bill; large seeds are hammered into smaller portions while they are held in the same manner.

Diet

Seeds, including oaks, pines, oats, thistles, weeds, and poison oak; and terrestrial invertebrates, including leafhoppers, treehoppers, jumping plant lice, aphids and scales, homopterans, caterpillars beetles, ants and wasps. Common visitor to bird feeders in wooded areas.

Behavior and displays

• Actively moves from branch to branch and tree to tree.

• Prefer to stay close to trees, flying between trees in shallow undulating motion. Flight from ground to elevated perches is more direct.

• Agonistic interactions with territorial intruders generally are accompanied by exchange of song (including counter-singing), harsh scolding notes, quivering of wingsh, and threatening posture with crest raised.

• Territories are defended by both members of a pair and used for foraging, nesting, roosting, and all other activities year-round.

Courtship

• Immature birds typically form pair bonds after of family groups breakup in summer; most birds are paired by early to mid fall.

• Pair bonds are permanent, unless one member of pair disappears.

Nesting

Nest Site: Female largely responsible for selecting site, which is primarily a natural tree hole or woodpecker-excavated cavity in main branches, secondary branches, or trunks; also use natural holes in stumps. May partially excavate own nest in soft or rotten wood, or may alter or further excavate existing cavity. Readily uses nest boxes and other artificial sites.

Height: Average about 12 feet (4 meters).

Nest: A cavity is usually altered or further excavated by both birds. A cup of hair, fur, and feathers placed on a base of grasses, bark strips, moss, and earth; built mainly, or entirely, by female.

Eggs: 6–8 white, usually unmarked eggs are sometimes speckled with very pale reddish-brown. Eggs are smooth, non-glossy, or only slightly glossy.

Incubation period: 14–16 days by female alone; male feeds the female as she incubates.

Nestling period: Young tended by both parents, both parents feed nestlings, but only female broods. On average, young fledge at 17 days.

Fledgling period: Young leave nest when capable of climbing to cavity entrance, between 16–21 days; they do not fly out of the nest, although they are presumably capable of flying short distances. Parents lead fledglings to foliage, which is used for cover and roosting. Young remain with parents for 3–4 weeks.

Broods: Single brooded.

Cowbird Parasitism: Not known to occur.

Notes

• Adequate roosting cover is an important habitat requisite for Oak Titmouse. Roost sites include natural or artificial cavities, as well as dense evergreen foliage.