B. i. sequestratus, B. i. griseus, B. i. murinus, B. i. affabilis, B. i. transpositus,
B. i. mohavensis, B. i. cinceraceus
Colorado Desert Bioregion:
Found at the Santa Rosa mountains at 6000 ft, Riverside County.
II. Current breeding distribution:
A. Expert opinion:
Breeder in the Mendocino National Forest 1996 and 1997. (PRBO data)
Sacramento Valley Bioregion:
Detected during the breeding seasons 1997 and 1998 at the East Park Reservoir. (PRBO data)
In 1997 and 1998 recorded as a known breeder at the Lower Sacramento River Project. (PRBO data)
Counted at the Tejon Ranch, Kern County and the California and Blodgett Forest Research Station, El Dorado County. (Block and Morrison 1987)
Bay Delta Bioregion:
Recorded during point counts 1995-1998 at Cosumnes River Preserve. (PRBO data)
During 1996 – 1998 field season Oak Titmice were banded at the Lower Sacramento River Preserve. Number of females caught with brood patches were: 3 in 1996, 2 in 1997, and 1 in 1998. (PRBO data)
Bay Delta Bioregion:
Recorded 8 females with brood patches in 1995, and 3 in 1998 at Cosumnes River Preserve. (PRBO data)
Sacramento Valley Bioregion:
East Park Reservoir: 3 nests found in 1997, 1 in1998. (PRBO data)
Lower Sacramento River Project produced 8 nests in 1995 and 1 in 1998. (PRBO data)
Bay Delta Bioregion:
In 1996-1998 a mean number of 5 nests were found at the Cosumnes River Preserve. (PRBO data)
Central Coast Bioregion:
San Luis Obispo Co.: Breeding at Camp Roberts Military Base (Tietje and Vreeland 1997)
San Joaquin Bioregion:
Studied in nest boxes and cavities between 1989 and 1991 on the San Joaquin Experimental Range (Purcell 1995)
Between 1989 and 1990 Oak Titmice were abundant during searches both east and northeast of Shasta Valley, approximately 15-25 individuals per morning. (Cicero 1996)
Between 1990 – 1992 population densities west of Clear Lake through the Modoc Plateau ranged from 1-3 pair per day at Doris and Red Rock Valley and 4-7 pair per day west-northwest of Lava Beds National Monument. (Cicero 1996)
3-4 pair per day found at Walker Pass, Kern County during studies conducted 1989-1991. (Cicero 1996)
Only a few birds were sighted at White-Inyo Mountains, Inyo County, Black Rock Canyon, Joshua Tree Monument during 4 visits 1989-1991. (Cicero 1996)
Breeds in interior of eastern Marin County, including the hills around Novato. Rare and local on the Point Reyes Peninsula.
In the South Bay area the Oak Titmouse is found in the canyon bottoms
of the Diablo range and over most of the lower portions of the Santa Cruz
mountains. (Sibley 1952)
I. Other/Local opinion:
Found in 1998 at Bear Valley visitor center, Point Reyes National Seashore during unofficial search. (Humple pers. comm 1999)
I. Average territory size:
Mean territory size of 6.3 acres with a range of 3.3-12.5 acres in Alameda County. (Dixon 1949) In San Mateo County mean territory size was 2.0 acres. (Hertz et al, 1976)
II. Time of occurrence and seasonal movements.
B. Departure date from breeding grounds: N/A, year-round resident
C. Spring migration period: Year-round resident
E. Extent of wintering in CA: Year-round resident, defends territory throughout the year. (Verner and Boss 1980)
F. Migration stop-over needs/characteristics:
G. Stop-over period: N/A
H. Habitat use: N/A
III. Nest type: Secondary cavity nest using natural cavities, woodpecker holes and/or nest boxes (Dixon 1949)
V. Social Organization:
A. Typical breeding densities:
VI. Clutch size: Variable clutch size with a mean of 6.75. (Dixon 1949) At San Joaquin Experimental Range the mean clutch size was 5.81. (Purcell 1995) Range of 3-9 eggs, usually 6-8. (Ziener 1990)
VII.. Incubating sex: Female. (Dixon 1949)
VIII.. Incubation period: 14-16 days. (Dixon 1949)
VIX.. Nestling period: approximately three weeks. (Dixon 1949) The San Joaquin Experimental range reported a mean 41 day nestling period.(Purcell 1995)
X. Development at hatching: Altricial (Ehrlich et. al. 1988)
XI. Number of broods: Single brood. (Dixon 1949)
XII. Who tends the young: Both parents tend Young. (Dixon 1949)
A. Major food items (by season):
No season-specific information. In general 43% animal and 57% vegetable. (Dixon 1949) The animal food is made up of true bugs, caterpillars, beetles, wasps, ants, spiders, and other insects. Vegetable food contains cultivated fruits and grains, wild fruits, seeds and nuts, leaf galls, oak and willow catkins, and leaf buds. (Dixon 1949)
B. Drinking: Considered an occasional drinker (drank on half or fewer of the days with a maximum temperature of 25° C or above) based on Fisher water- dependence categories in Williams and Koenig, 1980.
XIV. Wintering ground needs and distribution: Same as on the breeding
BREEDING HABITAT AND NEST SITE CHARACTERISTICS:
I. Overview of breeding habitat:, Oak Titmice prefer a woodland habitat in which oaks predominate. (Grinnell and Miller, 1944) In Marin County Oak Titmice occupy woodlands, oak savannah, open broad-leaved evergreen forests, and riparian woodlands. The open broad-leaved evergreen forest must be spacious, have oaks, and be on south-facing slopes. (Shuford 1993) Oak and pine-oak woodland, arborescent chaparral, oak-riparian associations. (AOU 1998)
II. Nest Site.
B. Height of nest: Ranges from 3 – 32 ft. (Verner and Boss 1980)
III. Vegetation surrounding the nest (Importance of each category may differ by species)
IV. Landscape factors
SPECIAL FACTORS: Factors influencing a species occurrence and viability.
I. Brood parasitism: no information
II. Dietary: no information
III. Sensitivity to human-induced disturbance: no information
IV. Pesticide use: no information
V. Predators: Suffers depredation from the usual predators of passerines, namely small mammals and hawks. (Ziener 1990) Western Scrub Jay may depredate eggs and nestlings. (Bent 1946)
VI. Exotic species invasion/encroachment: The proliferation of the European Starling, may pose an indirect threat to the Oak Titmouse. (Purcell 1995)
VII. Other: The Protocalliphorid blowfly larvae are parasites of secondary
cavity nesters as they lay their eggs in the additional material used to
line the nest cavity. A high rate of parasitism was recorded in nests at
San Joaquin Experimental Range. (Purcell and Verner 1995)
POPULATION TREND: http://www.mbr.nbs.gov/bbs/bbs.html
Data censusing both the Oak and Juniper Titmice showed a 1.9% decline
per year throughout California (p<.05) 1980-1996 and a 1.6% annual decline
in the California foothills population of Oak Titmice during 1966-1996
(p=.06). (Sauer, 1996)
I. Age and sex ratios: no information.
II. Productivity measure(s): The San Joaquin Experimental Range study of cavity nesters reported a Mayfield estimate of nesting success of 62% in natural cavities and 60% in nest boxes. (Purcell 1995)
III. Survivorship: Two-thirds of the birds fledged did not survive until the next breeding season. (Dixon 1949)
According to Dixon (1949) dispersal is gradual and restricted, 4 of the 7 birds recorded established territories in their natal area the following season. The median distance of dispersal was approximately 600 meters. (Dixon 1949)
More information about the breeding requirements of the Oak Titmouse
is essential in forming management recommendations. The literature concerning
this species is primarily related to genetic variation and does not adequately
address breeding biology. More direct studies of breeding biology and habitat
requirements are suggested. Nest monitoring is one method that would be
helpful in assessing the status and needs of this species.
Section 2: Action plan summary.
STATUS (from subspecies, trend, local extirpations, state and
federal lists, etc.)
Experiencing a 1.9% decline per year throughout California (p<.05) 1980-1996 and a 1.6% annual decline in the California foothills 1966-1996 (p=.06). (Sauer, 1996)
HABITAT NEEDS (e.g., elevation, patch size, breeding habitat
Requires oak and pine-oak woodlands with adequate natural or excavated cavities for nesting and sufficient canopy cover for foraging and roosting.
CONCERNS (e.g., productivity, brood parasitism, habitat loss,
lack of information, wintering distribution, pesticide use)
Habitat is one major concern in the conservation of the Oak Titmouse. The loss of dead standing trees, live trees with dead limbs or diseased trees reduces the number of cavities available for nesting.
The significant decline since 1980 of this species requires further study to determine future conservation goals.
OBJECTIVES (e.g., increase distribution, identify healthy breeding
populations, increase available habitat, guide restoration efforts to benefit
The objective is to prevent further decline in this species and to increase suitable habitat.
ACTION (e.g., acquire and restore habitat, specific management
and restoration recommendations, specific research and monitoring needs,
specific land protection recommendations)
The reduction of habitat loss can be achieved by increasing the number of dead standing oak species, especially important are live trees with dead limbs and diseased trees in which the heartwood decays. These trees should remain standing for use by cavity-nesting birds. A canopy cover of 40-70% should be the objective when thinning oak woodlands.
Further research and monitoring is needed to gather more information specifically on the Oak Titmouse requirements.
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