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 I.Historical
references: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
. ECOLOGY:
. 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
. Woodfords90.250
. Ano
Nuevo310.248
. Yosemite
Natl Pk110.227
. Mineral
CA40.211
. Tehachapi80.190
. Oakland530.168
. Crystal
Springs270.167
. Sierra
Valley50.165
. San
Francisco220.146
. Santa
Rosa180.143
. Arcata280.138
. 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).
. VI.Displays:
. 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).
. XV.Diet:
. 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.
. D.Disturbance
. 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.
V.Other
. 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).
. DEMOGRAPHICS:
. 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.
. 7.Research
on the effect of pesticides on Brown Creepers.
. Adams,
E. M. and M. L. Morrison.1993.Effects
of forest stand structure and composition on Red-Breasted Nuthatches and
Brown Creepers.J. Wildl. Manage.
57(3):616-629.
. American
Ornithologist Union.1983. Checklist
of North American Birds.7th Edition.AOU,
Washington, D.C.
. Bent,
A. C.1964.Life
Histories of North American Nuthatches, Wrens, Thrashers, and Their Allies.Published
1948, reprinted by Dover Publications, New York.
. Davis,
C. M.1978.A
nesting study of the Brown Creeper. Living Bird. 17: 237-263.
. Franzreb,
K. E.1978.Tree
species used by birds in logged and unlogged mixed-coniferous forests.Wilson
Bulletin 90(2) 221-238.
. Franzreb,
K. E.1985.Foraging
ecology of Brown Creepers in a mixed-coniferous forest.J.
Field Ornithol. 56(1): 9-16.
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J. and A. H. Miller.1986.The
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Vining, CA.
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J. C.1999.Influence
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Wildl. Manage. 63(2):484-496.
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J. C. 1999.Hierarchical comparisons
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89-99.
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and wildfire effects over 30 years.Ecological
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bird communities in the southern washington cascade range. In Wildlife
and Vegetation of Unmanaged Douglas-Fir Forest, USDA Forest Service Gen.
Tech. Rep. PNW-GTR-285.pp207-218.
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R. W. and J. M. Mariani.1991.Nesting
habitat and abundance of snag-dependent birds in the southern Washington
Cascade range. In Wildlife and Vegetation of Unmanaged Douglas-Fir Forest,
USDA Forest Service Gen. Tech. Rep. PNW-GTR-285.pp
221-240.
. Mannan,
R. W., E. C. Meslow and H.M. Wight.1980.Use
of snags by birds in Douglas-fir forests, Western Oregon.J.
Wildl. Manage.44(4):787-797.
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J. M. and D. A. Manuwal.1990.Factors
influencing Brown Creeper (Certhia Americana) abundance patterns in the
southern Washington Cascade Range.Studies
in Avian Biology No. 13: 53-57.
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M. L., K. A. With, I. C. Timossi, W. M. Block, K. A. Milne. 1987.Foraging
behavior of bark-foraging birds in the Sierra Nevada.The
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D. H.1970.Ecological
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A.1994.California
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