Summary of status, habitat needs, concerns, objectives, and recommended action items, derived from species account authors and 6/23/00 meeting.
. SUBSPECIES STATUS: None presently observed by AOU. Grinnell and Miller (1944) recognized Certhia familiaris zelotes and Certhia familiaris occidentalis in California.
. MANAGEMENT STATUS:No official status
. RANGE MAPS (California):
. Historical distribution maps (subspecies): Grinnell and Miller
. BBS map
. Christmas bird count map
. I.Historical references:
. Grinnell and Miller (1944) distinguished two Brown Creeper subspecies in California.Certhia familiaris zelotes, is a Transition Zone resident, with “partial and irregular emigration in autumn” to lower elevations.It was considered common “under optimum habitat conditions,” but they state that “removal of old forest likely has reduced aggregate population.”Its range covered almost the entire length of the state:east of the coast belt and west of the southeastern deserts.In the north, it extended east to the Warner Mountains, Modoc County; west to include Siskiyou and Salmon mountains, Siskiyou County.It extended south along the inner Coast Ranges, nearly to the Strait of Carquinez.Its range included the entire Sierra Nevada continuously, with patchy distribution south of Tehachapi, on higher mountains as far as Cuyamaca Mountains, San Diego County.Grinnell and Miller (1944) described its habitat as mature forest, particularly conifers (incense cedar, white, red and douglas firs, yellow, jeffrey and lodgepole pines), but also deciduous trees (black oak, aspen, cottonwood, alder; in winter:valley, live and blue oaks).
. The range forCerthia familiaris occidentaliswas described as the coastal strip south of the Oregon line in Del Norte County and as far south as Moneterey County, from sea level up to 3700 feet.It was found in the “densest and oldest forests available,” particularly original stands of coast redwood (Grinnell and Miller 1944).
. II.Current breeding distribution:
. The Brown Creeper is a “fairly common resident within the forests of its breeding range” (Small 1994).It breeds south of the Oregon border through the Klamath Mountains and the Northern Coast Range to San Francisco Bay; from San Francisco Bay south, in the Southern Coast Range to Morro Bay, and in the San Rafael Mountains (Small 1994).It also breeds in the mountains of the northern Modoc Plateau, the Warner Moutnains and the White Mountainns, the Inyo Mountains, the southern Cascades south to northern Kern county and the Mt. Pinos area mountains.In southern California it is found in the San Gabriel, San Bernardino, San Jacinto and Santa Rosa mountains and at upper elevations in San Diego County (Small 1994).
. BBS relative abundance data (1966 to 1996) by region in California:
. AreaRelative abundance
. Sierra Nevada4.3
. South Pacific Rainforests3.9
. Los Angeles Ranges1.2
. Pitt-Klamath Plateau1.1
. California Foothills0.6
. Basin and Range0.06
. I.Average territory size:In a white cedar bog in Michigan, territory size ranged from 2.3 to 6.4 hectares (Davis 1978).
. II.Time of occurrence and seasonal movements.
. A.Arrival date on breeding grounds:
. The breeding season in California, based on nest records, ranges from April 16 through July 11; Bent (1964) notes that the height of the breeding season as May 19 through June 11 (17 nest records found).
B.Departure from breeding grounds:
. Some Brown Creepers at higher elevations move downslope in the fall, with great variation in numbers migrating from year to year (Small 1994).In some years, during “sporadic fall migrations,” Brown Creepers disperse to “the deserts, the valley floors and the coast” (Small 1994).Fall dispersal may occur as early as late August, with maxium numbers recorded during October (Small 1994).
. C.Spring migration period:Information on spring movement is not available (Small 1994).
D.Fall migration period.See B.
. E.Extent of wintering in California:from Christmas bird count 1999
. Countynumber reportedNumber/party hour
. Big Sur450.508
. Santa Cruz970.433
. Ano Nuevo310.248
. Yosemite Natl Pk110.227
. Mineral CA40.211
. Crystal Springs270.167
. Sierra Valley50.165
. San Francisco220.146
. Santa Rosa180.143
. Moss Landing350.118
. Grass Valley160.113
. Monterey Peninsula200.109
. Palo Alto250.106
. Clear Lake80.101
. III.Migration stop-over needs/characteristics:
. A.Stop-over period:No information.
. B.Habitat use:No information.
. C.Routes:No information.
. IV.Nest type:
. Nests are built behind a loose slab of bark still attached to a living or dead tree; the nest is a hammock-like cup with a foundation of twigs, leaves, bark shreds; and lined with finer bark, grasses, feathers, mosses.The female builds the nest (Franzreb 1985).Building may take a month (Franzreb 1985).Brown Creepers may occasionally nest in holes in trees if loose bark is not available (Harrison 1979).
. V.Foraging strategy:
. Brown Creepers use their slightly decurved bill to pick food items from cracks and crevices and off the bark surface (Davis 1978).Typically, Brown Creepers climb upward along the trunk, often spiraling around the trunk, then drop down to the base of another tree when they reach a certain height (Bent 1964).Birds have been observed starting 1 meter off the ground, working their way up the trunk to within 1-3 meters of the tree top, then flying to the trunk of another tree (Franzreb 1985).The point at which birds switched to another tree often coincided with an increase in branch density, probably making it difficult for the bird to maneuver on the trunk (Franzreb 1985).Peck-probe was the most common foraging strategy (92.5% of observations), followed by gleaning (6.9% of observations) and hawking (0.6% of observations) (Franzreb 1985).
. Brown Creepers forage predominantly on the bole (98%) of a tree, spending more time foraging in the lower bole (67%) than the upper bole (19%) (Weikel et al. 1999).Creepers are sometimes observed in the lower crown but not in the upper crown (Weikel et al. 1999).
. In courtship displays a male may “launch out from a tree and at top speed twine around another tree, or weave in and out among the surrounding tree and branches” (Bent 1964).
. Courtship feeding of the female by the male takes place until egg hatching (Davis 1978).
. In Michigan, territorial singing occurred commonly from April until the young fledged (Davis 1978).
. VII.Social Organization:
. A.Typical breeding densities:In western Oregon, Brown Creeper total density during the breeding season increased with douglas-fir stand age:0 per 40 hectares in 10 year-old stands; 3 per 40 hectares in 35 year-old stands; 8 per 40 hectares in 75 year-old stands; 19 per 40 hectares in 110 year-old stands; 46 per 40 hectares in 200 year-old stands (Mannan et al. 1980).In old-growth hemlock-white pine-hardwood forest (Appalachian Plateau, Pennsylvania) there were 1.58 breeding territories per 10 hectares (Haney 1999).
. B.Mating system: Monogamous (Davis 1978)
. C.Delayed breeding: No information.
. D.Post fledging biology of offspring:Fledgling groups initially remain within a 500-meter radius of the former nest (Davis 1978).At seventeen days after fledging, young creepers still occasionally begged and were fed (Davis 1978).Bent (1964) reports that young of the year may be attended by adults up to the first week in September.However, Davis did not find any family groups after mid-July (1978).
. E..Post breeding social behavior:In winter Brown Creepers are found with flocks of feeding bush-tits, kinglets, chickadees and nuthatches (Bent 1964).
. VIII.Clutch size:From 4 to 8 eggs to a clutch, most commonly 5 or 6 (Bent 1964)
. IX.Incubating sex: Both sexes.
. X.Incubation period:15 days (Davis 1978). Incubation begins after the clutch is complete (Davis 1978).
. XI.Nestling period: Bent (1964) reports that young leave the nest within 13 - 14 days of hatching.Davis (1978) reports that they leave the nest 15-16 days after hatching.
. XII.Development at hatching: Altricial (Davis 1978).
. XIII.Number of broods:In Michigan, renesting attempts followed nesting failures, but a pair never attempted to renest after successfully fledging their brood (Davis 1978).
. XIV.Who tends the young: The male and the female feed the young (Davis 1978).
. A.Major food items(by season):Brown Creepers feed on weevils, leaf beetles, flat-bugs, jumping plant lice, leaf hoppers, scale insects, eggs of katydids, ants, and other small hymenoptera, sawflies, moths, caterpillars, cocoons of leaf “skeletonizers” (Bucculatrix), pupae of the coddling moth, spiders, and pseudoscorpions (Bent 1964).In the spring, Brown Creeper abundance was positively correlated with the abundance of spiders (6-11 mm) in the western hemlock zone of the Washington Cascade range (Mariani and Manuwal 1990).Nestlings are fed ants, click beetles, moths, harvestmen, mayflies and spiders (Davis 1978).
. B.Drinking:No information.
. XVI.Wintering ground needs and distribution:
. Winter can be a critical season for resident bird species (Huff et al. 1991).Data from the Washington Cascade range suggests that old-growth forest stands provide better winter habitat for Brown Creepers than do younger stands (Manuwal and Huff 1987, Huff et al. 1991).The mean abundance of the bark insectivore guild (Red-breasted nuthatch, Brown Creeper, Hairy Woodpecker, Pileated Woodpecker, Red-breasted sapsucker) was consistently higher in late-seral (325-600 years) than mid-seral (65-140 years) douglas-fir forest (Huff et al. 1991). Brown Creeper abundance in particular increased with western hemlock basal area (Huff et al. 1991).The higher abundance of bark foragers in that late- and mid-seral stands might be due to the higher number of large-diameter (> 100 cm in dbh) trees with well-protected furrows which provide protection for overwintering arthropods (Huff et al. 1991).
. BREEDING HABITAT AND NEST SITE CHARACTERISTICS:
. I.Overview of breeding habitat:
. Several studies indicate that Brown Creeper breeding densities increase with stand age.In Douglas-fir stands of western Oregon, Brown Creeper densities were greatest in 200 year-old stands (Mannan et al. 1980).In the Washington Cascade Range, Brown Creepers were most abundant during the breeding season in mesic old growth stands (210-730 years old) (Lundquist and Mariani 1991).Brown Creepers were significantly less abundant in young (55-80 years old) stands than older stand types (mature: 95-190 yrs; old-growth: 210-730 yrs) (Lundquist and Mariani 1991).
. Brown Creeper numbers are positively correlated with densities of douglas-fir snags (> 50 cm in dbh) (Lundquist and Mariani 1991).White pine snags were particularly important as nesting trees (Lundquist and Mariani 1991).
. II.Nest Site.
. A.Substrate: living or dead tree.
. In a study of snag tree use, Brown Creepers selected large dbh snags as nest trees in old-growth stands (dbh greater than 50 cm); in second growth stands, snags 20-49 cm dbh were most often used (Lundquist and Mariani 1991).Eighty percent of active Brown Creeper nest snags were of decay class 2 (few limbs, no fine branches, top broken; age of snags 5-18 years) (Lundquist and Mariani 1991).
. B.Height of nest:Range of 5-15 feet above ground (Harrison 1979).In douglas-fir stands, average nest height was 9.5 meters above ground.
. C.Height of plant:Average tree diameter at nest: 44 cm; Average nest tree dbh: 59 cm; Average nest tree height: 25 m (Lundquist and Mariani 1991).
. D.Nest concealment:Behind slab of bark on living or dead tree.
. III.Vegetation surrounding the nest
. A.Canopy cover:No information.
. B.Dominant plant species in canopy:No information.
. C.Average shrub cover:No information.
. D.Dominant shrub species:No information.
. E.Average forb cover:No information.
. F.Dominant forb species:No information.
. G.Ground cover:No information.
. H.Slope:No information.
. I.Aspect:No information.
. J.Tree DBH:No information.
. K.Snags:No information.
. L.Distance to water:No information.
. IV.Landscape factors
. A.Elevation:Nesting occurs at elevations from near sea level up to at least 9500 feet (Grinnell and Miller 1944).
. B.Patch size. No information.
. C.Fragmentation.No information.
. Brown Creepers appear to be sensitive to logging practices:They did not use a logged area (moderately heavy overstory removal; 167 trees per hectare remaining) during the breeding season (White Mountains, Arizona) (Franzreb and Ohmart 1978).
. In headwater riparian stands in the western hemlock vegetation zone, Brown Creepers were more abundant in unlogged areas than in buffer strips adjacent to logged areas (Hagar 1999).Brown Creeper abundance increased as buffer width increased (Hagar 1999).In buffers greater than 80 meters wide (width measured on one side of stream), Brown Creeper abundance approached minimum abundance in unlogged sites (Hagar 1999).
. E.Adjacent land use.No information.
. SPECIAL FACTORS:Factors influencing a species occurrence and viability.
. I.Brood parasitisim: Although brood parasitism does not appear to be a concern, it could become more prevalent with increased fragmentation and associated edge effects.Davis (1978) found one abandoned nest containing two Brown-headed Cowbird eggs; it is not clear whether parasitism occurred after the nest abandonment (Davis 1978).Friedman (1963) has one instance of a pair of Brown Creepers feeding a fledged cowbird (Davis 1978).
. II.Dietary:Brown Creepers forage on a variety of tree species of different sizes.In both old-growth and second growth forest stands of the western hemlock zone, the trunks of large Douglas-fir trees (greater than or equal to 50 cm dbh) were the only substrates used disproportionately as foraging sites by Brown Creepers during spring and winter (Mariani and Manuwal 1990).Although tree dbh is not necessarily an indicator of greater arthropod numbers, bark furrows in Douglas-firs increase in depth and surface area with increasing bole diameter, potentially increasing the number of arthropods present (Mariani and Manuwal 1990).Larger dbh trees provide deeper bark furrows, which increases available foraging substrate without substantially increasing the actual area over which a bird has to move to search for prey (Mariani and Manuwal 1990).Brown Creepers may be able to increase their energy intake by foraging on one large diameter Douglas-fir tree versus numerous small trees (Mariani and Manuwal 1990).
. In young even-aged douglas-fir stands (30-45 years, planted after a fire), Brown Creepers selected trees in relation to the depth of furrows in the bark, the number of crown connections (number of trees whose crowns directly intermingled with the crown of the focal tree), and the number of dead branches (as seen from the upslope side of the focal tree) (Weikel et al. 1999).
. In a mixed conifer zone of the Sierra Nevada, Brown Creepers preferentially used stands providing two components:a diverse tree structure, including an overstory of large pines and firs (sugar pine and douglas fir) in combination with relatively smaller-diameter cedars and pines (especially ponderosa) that provided high arthropod abundance (Adams and Morrison 1993).Brown Creepers foraged more on incense cedar, which had the highest arthropod density throughout the year, than on any other tree species (Adams and Morrison 1993).Arthropod abundance on incense cedar, sugar pine and black oak was higher in trees with smaller dbh(Adams and Morrison 1993).
. Brown Creepers in the White Mountains (Arizona) foraged preferentially on ponderosa pine, douglas-fir and snags (preference was described as a significant difference in use vs availability of the tree) (Franzreb 1985).Brown Creepers selectively foraged on trees greater than 27 meters in height (Franzreb 1985).
. III.Sensitivity to human-induced disturbance:No information.
. IV.Pesticide use:No information.
. V.Predators:Davis (1978) found three predated nests.One, containing eggs, might have been predated by Red Squirrels (Tamiasciurus hudsonicus) (Davis 1978).
. VI.Exotic species invasion/encroachment:No information.
. VII.Other: No information.
. POPULATION TREND:
. BBS data indicate a non-significant decline in California (-2.21, p=0.06) between 1966 and 1998.Brown Creeper trends show non-significant declines in the Pitt-Klamath Plateau (-2.1, p=0.34), California Foothills (-2.3, p=0.33), Los Angeles Ranges (-2.9, p=0.61) and Sierra Nevada (-3.0, p=0.24).
. According to the Christmas Bird Count data, Brown Creeper relative abundance has significantly increased in California between 1959 and 1988 (trend=2.2 % per year; p<0.01).
. I.Age and sex ratios:No information.
. II.Productivity measure(s):In Michigan, 58% of the nests containing at least one egg or nestling succeeded in fledging young (Davis 1978).
. III.Survivorship:No information.
. IV.Dispersal:No information.
. MANAGEMENT ISSUES:
. Brown Creepers make greater use of forest stands that are diverse in physical structure and tree species composition (Adams and Morrison 1993).They may forage on different species and sizes of trees than those used for nesting (Lundquist and Mariani 1991). On the western slope of the Sierra Nevada, Brown Creeper foraging was correlated with percent basal area of sugar pine throughout the year (Adams and Morrison 1993).Intensity of stand use was correlated with sugar pine, which is rarely replanted in the Sierra Nevada due to mortality from white pine blister rust (Laacke and Fiske 1983, 7).Incense cedar, which has high arthropod density, is an important foraging tree throughout the year (Adams and Morrison 1993). Brown Creeper abundance could be negatively affected by a decrease in incense cedar presence (Morrison et al. 1987).
. The current trend in the Sierra Nevada toward conversion of mixed conifer to monotypic stands of ponderosa pine or mixed stands of ponderosa pine and lesser amounts of douglas-fir and fir, could negatively impact Brown Creeper foraging sites (Morrison et al. 1987).Although Brown Creepers use ponderosa pine when it occurs in mixed stands, they seldom forage in stands of homogeneous ponderosa (Adams and Morrison 1993).
. During the breeding season, Brown Creepers are sensitive to logging. In logged sites, maintaining riparian buffer widths greater than 80 meters increases Brown Creeper abundance.Nesting habitat should include large diameter snags. Lundquist and Mariani (1991) recommend the use of mean nest tree diameter (50 cm dbh) as a guideline for managing for snags.
. In areas where logging is taking place, management recommendations include:Harvest rotations that increase the potential of the forest to produce or retain large snags (the lengthening of rotation periods to more than100 years) (Mannan et al. 1980); retention of large snags in clear-cuts and thinning cuts, and creation of snags from living trees in areas where large snags are not present; the maintenance of old stands of timber in riparian buffer zones (Cline et al. 1980).
. ASSOCIATED SPECIES:
. Brown Creepers have been found breeding in association with Chestnut-backed Chickadees, Golden-crowned Kinglets and Audubon Warblers (Bent 1964).
. Management for bark gleaning birds, because of their dependence on certain sizes and species of trees for foraging, will benefit old-growth and snag requiring species (Morrison et al 1987, Adams and Morrison 1993).Some species which would benefit from Brown Creeper habitat protection include the Red-breasted Nuthatch, Hairy Woodpecker, Pileated Woodpecker, Red-breasted Sapsucker, and other cavity-nesting birds.
. Changes in forest structure can affect resource partitioning among different species of bark-foraging birds.In the Sierra Nevada, different species of bark-foraging birds used different combinations of foraging behaviors:For example, creepers and nuthatches foraged at different average heights, and the nuthatches used a wider range of foraging substrates (Morrison et al. 1987).“A change in the species or size composition of the forest would likely alter the pattern of resource use” by bark-foraging birds (Morrison et al. 1987).
. MONITORING METHODS AND RESEARCH NEEDS:
. 1.Locate high quality Brown Creeper areas in California for protection, and to study suitable site characteristics.
. 2.In depth monitoring in the regions where BBS surveys are indicating a decreasing, though non-significant, trend.Look into landscape or management changes in these areas that might be impacting Brown Creeper habitat.
. 3.Research on the effect of forest management practices in California forests, since most research has taken place outside of California.
. 4.Nest productivity studies:How do landscape factors, disturbance, and management practices impact productivity?
. 5.Impact of fragmentation:Determine territory size/patch size requirements.Determine impact of fragmentation on foraging, survivorship and nest productivity.
. 6.Research on dispersal:Very little is known on seasonal movement, distances traveled, landscape factors limiting dispersal ability, or habitat requirements during dispersal.
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