Brown Creeper Research Articles

The Effects of Shelterwood Logging on Bird Community Composition in the Black Hills, Wyoming

Abstract The Black Hills of Wyoming and South Dakota are characterized by a complex history of both natural and human disturbance regimes. Historically, ponderosa pine (Pinus ponderosa) communities were characterized by frequent, cool ground fires. Intensive fire suppression and timber harvest throughout the past century have drastically altered the structure of existing forests. Today, much of the area has been harvested using shelterwood logging resulting in open even-aged stands. The goal of this study was to compare bird communities in treated (areas that have recently been harvested) and untreated (areas receiving minimal silvicultural treatment) in the past 40 yr. Of the 20 commonly observed bird species, 3 species [red-breasted nuthatch (Sitta Canadensis), brown creeper (Certhia Americana), and ovenbird (Seiurus aurocapillus)] were conspicuously less abundant in treated than in untreated stands. Eleven other species were more abundant in treated stands, while six species showed no response to treatment. Although bird species diversity and the abundance of birds were highest in treated stands, this does not imply that logging is beneficial to the entire bird community. The abundance of particular bird species may appear to have increased, but the composition of the bird community has been altered. As more of the forested areas are harvested, the bird community will shift from one with birds typical of both open pine and dense pine forest to one dominated by ground foraging species. FOR. SCI. 48(2):365–372.

Impact of an ice storm on resident bird populations in eastern North America

The January 1998 ice storm was very dramatic, particularly in Québec, with five days of nearly non-stop freezing rain and temperatures below 0 °C. We compared results of Christmas Bird Counts (complete counts conducted during one day within a 12-km radius by volunteers in winter) conducted before (1997–1998) and after (1999) the storm in control areas (16 sites) and in affected areas (15 sites). Abundance ratios (after/before) were significantly higher in control versus affected sites for Rock Dove Columba livia, Mourning Dove Zenaida macroura, Hairy Woodpecker Picoides villosus, Blue Jay Cyanocitta cristata, Black-Capped Chickadee Parus atricapillus and House Sparrow Passer domesticus. Paired -t- tests also indicated that the abundance of Brown Creeper Certhia americana and Downy Woodpecker Picoides pubescens was lower in affected sites following the storm. Only European Starling Sturnus vulgaris abundance increased significantly in affected sites. Species found in open habitats that forage mostly on the ground were less affected by the storm than tree foragers were. The effect of the storm on bird populations was quite significant and increased frequency of such storms could have drastic consequences on bird populations in the long term. Key words: ice storm, birds, Christmas Bird Counts, winter survival, climate change

Response of Passerine Birds to Forest Edge in Coast Redwood Forest Fragments

Abstract The response of passerine birds to forest edge was examined in old-growth and mature second-growth coast redwood (Sequoia sempivirens) forest in northern California. The study objectives were to determine which common passerine species are sensitive to edges during the breeding season and to estimate edge width for forest interior species. Response to edge was measured along twelve 100 × 400 m plots extending from the edge into the forest interior to obtain relative density of birds. Plots were surveyed 4 to 5 times in 1996 and 8 to10 times in 1997. We found that 14 common passerines showed a gradient of edge sensitivity. Steller's Jay (Cyanocitta stelleri) and Swainson's Thrush (Catharus ustulatus) had higher relative densities near edges than in the forest interior (P < 0.05) and were categorized as edge species. Brown Creeper (Certhia americana), Winter Wren (Troglodytes troglodytes), Pacific-slope Flycatcher (Empidonax difficilis), and Varied Thrush (Ixoreus naevius) had lower relative densities near edges (P < 0.05) and were categorized as interior birds. Based on exponential regression models, estimated edge widths were 140 m for Varied Thrushes, 85 m for Brown Creepers, 120 m for Winter Wrens, and 125 m for Pacific-slope Flycatchers. Creation of edges would probably benefit Steller's Jays (which may be a nest predator), may not benefit Swainson's Thrushes, and may be detrimental to species that avoid edges. We recommend that edge effects be taken into consideration when planning for the conservation of bird species in the region.

Breeding Bird Response to Riparian Buffer Width in Managed Pacific Northwest Douglas-Fir Forests

We examined the relative importance of riparian vs. upland habitats to breeding birds by comparing species abundance, richness, and similarity of bird communities in managed Douglas-fir forests in western Washington State, USA. We also examined whether forested buffer strips along second- and third-order streams effectively maintain the pre-logging riparian breeding bird community by comparing species abundance, richness, and turnover among three treatments: (1) unharvested controls; (2) sites that were clear-cut, leaving a narrow (∼14 m) forested buffer on both sides of the stream; and (3) sites that were clear-cut, leaving a wide (∼31 m) forested buffer along both sides of the stream. Deciduous trees, berry-producing shrubs, and other deciduous shrubs less common in adjacent upland forest characterized streamside zones. Despite different vegetation features, riparian and upland habitats did not differ in any measures of bird species richness and composition. No species or species group was more abundant in the upland. Neotropical migrants, resident species, and species associated with deciduous trees and shrubs in forested habitats were more abundant in riparian habitats than in adjacent uplands. Total bird abundance and abundance of four species (American Robin [Turdus migratorius], Pacific-slope Flycatcher [Empidonax difficilis], Black-throated Gray Warbler [Dendroica nigrescens], and Winter Wren [Troglodytes troglodytes]) were higher in riparian habitats. Abundance of these riparian associates was correlated with percent cover of berry-producing shrubs and the number of deciduous trees in the canopy. We found that the number of breeding bird species on sites with narrow buffers increased from slightly fewer than controls before harvest to an average of 10 more species than controls after harvest, a change reflected in an average 20% increase in species turnover on narrow-buffer sites relative to controls. Total bird abundance did not differ between treatments and controls. Resident species, those species associated with shrubs in forested habitats and conifer trees, declined on both buffer treatments. Species associated with upland and riparian forests (Black-throated Gray Warbler, Golden-crowned Kinglet [Regulus satrapa], and Brown Creeper [Certhia americana]) decreased in abundance on riparian buffer treatments relative to controls, whereas species associated with open, shrubby habitats (Dark-eyed Junco [Junco hyemalis], Cedar Waxwing [Bombycilla cedrorum], and Song Sparrow [Melospiza melodia]) increased in abundance on one or both riparian buffer treatments. High species turnover on narrow-buffer treatments indicated that buffers <14 m on each side of the stream did not maintain the pre-logging bird community. There was little difference in species turnover or species richness between the wide-buffer treatment and the control, indicating that a 30-m buffer on both sides of second-order and third-order streams maintains most of the pre-logging bird community in the first two years postharvest. The Black-throated Gray Warbler was the only riparian associate to decline on both the narrow- and wide-buffer treatments; its abundance was positively correlated with buffer width, and a buffer ≥45 m wide on each side of second- and third-order streams was needed to support populations at densities found on unharvested controls. To maintain the entire breeding bird community associated with forested riparian habitats in the coastal Northwest, we recommend a minimum buffer of 45 m along both sides of second- and third-order streams. Habitat features such as deciduous trees (Alnus rubra and Acer macrophyllum) and berry-producing shrubs (especially Rubus spectabilis) appear to be important and should be maintained within forested riparian buffer strips. This study documents short-term effects of riparian treatments on the breeding bird community, which may take several years to respond to habitat manipulations. Thus, we recommend continued monitoring to assess long-term effects of buffer width reduction.

RESPONSE OF PASSERINE BIRDS TO FOREST EDGE IN COAST REDWOOD FOREST FRAGMENTS

Abstract The response of passerine birds to forest edge was examined in old-growth and mature second-growth coast redwood (Sequoia sempivirens) forest in northern California. The study objectives were to determine which common passerine species are sensitive to edges during the breeding season and to estimate edge width for forest interior species. Response to edge was measured along twelve 100 × 400 m plots extending from the edge into the forest interior to obtain relative density of birds. Plots were surveyed 4 to 5 times in 1996 and 8 to10 times in 1997. We found that 14 common passerines showed a gradient of edge sensitivity. Steller's Jay (Cyanocitta stelleri) and Swainson's Thrush (Catharus ustulatus) had higher relative densities near edges than in the forest interior (P < 0.05) and were categorized as edge species. Brown Creeper (Certhia americana), Winter Wren (Troglodytes troglodytes), Pacific-slope Flycatcher (Empidonax difficilis), and Varied Thrush (Ixoreus naevius) had lower relative densit...

Vocalizations and relationships of Brown Creepers Certhia americana: a taxonomic mystery

Two taxa of creepers (Certhia spp.) occur in Europe, C. familiaris and its sibling species C. brachydactyla. The North American Brown Creeper was considered a close relative of C. brachydactyla by one author, a close relative of or conspecific with C familiaris by others, and more recently as a distinct species, C. americana, by the American Ornithologists' Union. Songs of these three creepers are comprised mostly of social calls which are derived from begging calls. Sequence of syllables (syntax) is very conservative in songs of European population of C. familiaris and C. brachydactyla. In contrast, syntax in songs of western North American C. americana is highly variable; however, syllable morphology and syntax in some populations or individuals within populations is remarkably similar to songs of C. brachydactyla, notably from France and Spain. Two social calls and sleeping behaviour of C. americana are also similar to those of C. brachydactyla. Either C. americana and C. brachydactyla are close relatives or they have characters retained from the ancestor common to all three species whereas those in extant C familiaris have diverged.

Comparing bird assemblages in successional black spruce stands originating from fire and logging

Comparisons of the effects of logging and fire as disturbance agents on the composition of bird assemblages in boreal ecosystems are still lacking or are limited to the short-term impacts of clear-cutting. In Quebec, where the boreal forest is largely dominated by black spruce (Picea mariana (Mill.) B.S.P.) stands, we surveyed 140 point-count stations in 3 postlogging and 4 postfire development stages determined according to the height of the regenerating spruce trees. Species richness did not vary among forest development stages, but bird abundance was higher in recent clearcuts. Recently disturbed areas were characterized by open-land bird assemblages dominated by Neotropical migrants, which reached their highest abundance in clearcuts. Moreover, logged stands were distinguished from burned sites by the absence of cavity-nesting birds. Forest-bird assemblages reestablished themselves as soon as young spruces reached the sapling stage. However, the Black-backed Woodpecker (Picoides arcticus), Three-toed Woodpecker (Picoides tridactylus), and Brown Creeper (Certhia americana) were restricted to mature stands or recent burns and are thus likely to be negatively affected by modern forestry, which involves fire suppression and short logging rotations. We suggest that retention of larger areas of continuous mature forest might be essential to maintain these species in managed regions.

CHANGES IN BIRD COMMUNITIES IN BOREAL MIXEDWOOD FOREST: HARVEST AND WILDFIRE EFFECTS OVER 30 YEARS

A current paradigm in conservation biology is that forest harvest practices that better approximate natural disturbance processes are more likely to conserve biodi- versity. We contrasted bird communities in three replicate stands in each of 1, 13-15, and 22-28 yr old forests following wildfire and harvest in north-central Alberta, Canada. Stands were chosen from old (>120 yr) boreal mixedwood forests having -95% of the canopy trees killed during fire, and harvested sites retaining an average of 6% of the pre-harvest canopy trees. For all age classes, postharvest sites tended to have greater bird abundance. Species composition also differed between these treatment types. Two-Way Indicator Spe- cies Analysis (TWINSPAN) identified five major ecological groupings of species that dif- fered between wildfire and harvest, and among stand ages. Correspondence analysis (CA) identified similar bird communities. Greatest differences between bird communities oc- curred immediately following disturbance, and gradual convergence of communities oc- curred throughout the first 28 yr after disturbance. Species associated with open shrub and grassland or riparian habitats were associated primarily with 1-yr postharvest stands. Three- toed Woodpeckers (Picoides tridactyla) and Black-backed Woodpeckers (P. arcticus), to- gether with other species that use snags for foraging or nesting, occurred primarily in 1- yr postwildfire stands. Convergence in avian communities was correlated with the loss of standing snags on postwildfire sites. However, differences in bird communities were ap- parent up to 28 yr following disturbance, and this lack of complete convergence has im- portant consequences for sustainable forestry practices designed to maintain biodiversity in the boreal mixedwood forest. Notably, Connecticut Warbler (Oporornis agilis), Brown Creeper (Certhia americana), Winter Wren (Troglodytes troglodytes), and American Robin (Turdus migratorius) had higher densities on postwildfire than on postharvest stands. Lin- coln's Sparrow (Melospiza georgiana), Alder Flycatcher (Empidonax alnorum), Tennessee Warbler (Vermivora peregrina), Black-and-white Warbler (Mniotilta varia), American Red- start (Setophaga ruticilla), Mourning Warbler (Oporornis philadelphia), Rose-breasted Grosbeak (Pheucticus ludoviciana), Canada Warbler (Wilsonia canadensis), and Pine Siskin (Carduelis pinus) had higher densities on postharvest stands, possibly due to the greater abundance, after harvest, of larger live residual trees and a taller and more dense shrub layer. Harvest designed to approximate stand-replacing fires may require the retention of more snags than is currently practiced. New approaches to fire salvage logging are also required to ensure adequate retention of standing dead trees on the landscape.

Fragmentation Effects on Forest Birds: Relative Influence of Woodland Cover and Configuration on Landscape Occupancy

Abstract: Habitat fragmentation has been shown to influence the abundance, movements, and persistence of many species. We asked the following questions: (1) Do species respond mainly to habitat loss or to the changes in habitat configuration resulting from this loss? (2) Do species exhibit sharp thresholds in their response to forest cover or configuration? We compared the relative influence of forest cover and configuration on 15 bird species in 33 landscapes (6.25 km2) in eastern Ontario, Canada. Forest cover in these landscapes varied between 3.4% and 66.8%. The metrics we used to quantify forest configuration were correlated to forest cover, so we regressed these configuration metrics against cover and used the residuals in logistic regression models. Of the 15 forest bird species included in the analyses, the presence of only 3 (Downy Woodpecker [ Picoides pubescens], Brown Creeper [Certhia americana], and White‐breasted Nuthatch [ Sitta carolinensis]) was not significantly related to either cover or configuration of woodland. Forest cover and configuration each were significant predictors of the presence of 6 species in landscapes occupied in both years, and 3 species responded both to cover and configuration. Models based on single years showed variability in the landscape characteristics that were significant predictors of the presence of each species. These results indicate that (1) landscape structure was an important predictor of bird distribution, (2) both forest cover and configuration were important predictors of species presence, and (3) responses were species‐specific. Effects of forest cover and configuration on species presence generally were not characterized by sharp thresholds, preventing the application of simple management rules. Although forest cover is an important feature of landscape structure, our results indicate that woodland configuration is a far from negligible component that should also be incorporated in conservation strategies.

Functional Roles in Mixed-Species Foraging Flocks: A Field Manipulation

the winters of 1995-1996 and 1996-1997 in woodlots within the agricultural landscape of Union and Delaware counties, Ohio. These topographically flat deciduous forest fragments consisted primarily of oaks (Quercus spp.), ashes (Fraxinus spp.), shagbark hickory (Carya ovata), sugar maple (Acer saccharum), and American beech (Fagus grandifolia). Each woodlot was completely surrounded by cultivated fields, lacked any connection to other woodlands, and was so small that it contained only one mixed-species flock. During the study period, such flocks were never observed to cross open ground into neighboring woodlots. In addition to the species mentioned above, the study woodlots usually contained one or two Red-bellied Woodpeckers (Melanerpes carolinus) and occasionally a Hairy Woodpecker (Picoides villosus) or Brown Creeper (Certhia americana). Sixteen woodlots were used in the experiment. Before each field season, four of the eight woodlots to be used in that year were randomly assigned to the control group and four to the parid-removal group. Control woodlots averaged 5.3 _+ SD of 2.2 ha in size, and removal woodlots averaged 5.5 -+ 2.1 ha. Each woodlot was used only once. From mid-December to mid-January each year, we trapped and mist netted birds attracted to feeders and wire-mesh suet cages. All Downy Woodpeckers and White-breasted Nuthatches were fitted with USFWS bands and uniquely colored plastic leg streamers for individual identification. Chickadees and titmice in control woodlots were similarly marked, but those in treatment woodlots were removed and released approximately 50 km away in suburban Columbus, Ohio. Observations of flocking behavior took place during two-hour visits to woodlots conducted between 0800 and 1600. To balance sampling across time of day and season, we alternated visits to treatment and control sites. Each woodlot was visited 10 times, or until new parids began arriving in the treatment woodlots in late February during the juvenile dispersal period (T. C. Grubb pers. obs.). During each visit, we assigned the location of individually marked birds to one of the 25 x 25-m blocks that formed a grid that covered the entire area of the woodlot.

The Foraging Ecology of Cavity-Nesting Birds in Young Forests of the Northern Coast Range of Oregon

Cavity-nesting birds are important components of the avifauna in Pacific Northwest forests and are of special concern to land managers because of their reliance upon snags for nesting habitat. Because most research and management has focused on nesting habitat of cavity-nesting birds, the foraging ecology of cavity-nesting birds has generally been neglected. We studied the foraging ecology of the Chestnut-backed Chickadee (Poecile rufescens), Red-breasted Nuthatch (Sitta canadensis), Brown Creeper (Certhia americana), and Hairy Woodpecker (Picoides villosus) in 30- to 45-year-old, Douglas-fir (Pseudotsuga menziesii) forests of the Coast Range of Oregon. All four species were selective in their use of foraging substrates. Hardwoods were selected over conifers by Chestnut-backed Chickadees and Hairy Woodpeckers. In relation to randomly chosen live trees, Chestnut-backed Chickadees, Red-breasted Nuthatches, and Hairy Woodpeckers selected trees that were larger in diameter, and Brown Creepers selected trees with deeper furrows in the bark. Large diameter, heavily decayed snags and logs were selected for foraging by the Hairy Woodpecker. Foraging needs should be taken into account when managing habitat for cavity-nesting birds.

Results of the Vermont Forest Bird Monitoring Program, 1989-1996

We conducted a statistical analysis of breeding census data from the first 8 years (1989-1996) of the Vermont Forest Bird Monitoring Program (FBMP). Data were collected at 17 study sites located in large tracts (= 40.5 ha) of mature, forested habitats in Vermont. A route regression model was used to produce population trends for 67 species and 3 groups of species categorized by wintering range. Power analyses conducted for 4 species revealed that the FBMP adequately sampled species which occurred on at least 9 or more of the 17 study sites and that our ability to detect small (=2%) population changes will increase dramatically after 15 years of monitoring. FBMP data showed signifi? cant declines in breeding populations of black-capped chickadee, solitary vireo, and Canada warbler, but a significant increase in rose-breasted grosbeak. When species were categorized by wintering range, neotropical migrants showed a significant overall increase and year-round residents declined. The negative trend for Canada warbler, corroborated by Breeding Bird Survey (BBS) data and migration monitoring data from Long Point Bird Observatory in Ontario, sug? gest that this species is experiencing widespread declines over a significant portion of its breeding range. Rates of population change in FBMP data were poorly correlated to BBS trends. We found significant positive correlations between Vermont's average winter temperatures and the relative abundances of brown creeper, downy woodpecker, and for all resident species combined. We evaluated the number of brown-headed cowbird occurrences by study site and physiographic region. Most cowbirds (95.3%) occurred at FBMP sites located in the predominately agricultural Champlain Lowlands, suggesting that even relatively large forested tracts in this region may be subject to high rates of cowbird parasitism.

Simulating forest and habitat change in south‐east Alaska with the landscape model PAYSAGE

We used the landscape model PAYSAGE to demonstrate the use of GIS and simulation models for ecosystem management over a portion of Mitkof Island in the Tongass National Forest. The objectives of the study were to: 1) depict the natural heterogeneity in environment and resource distributions across the study area; 2) quantify changes in vegetation and vertebrate habitats (brown creeper, orange‐crowned warbler, marten) during the period of commercial timber harvest (1954 to the present); and 3) simulate likely long‐term changes in vegetation and vertebrate habitat under three management scenarios – the Tongass Forest Plan, the wildlife habitat conservation strategy, and the Pacific Fisheries Task Force strategy. The results indicated that productive forest lands and vertebrate habitats are naturally patchy in the study area due to topography and climate. This natural fragmentation was exacerbated by past logging, which targeted high‐productivity old growth stands. This stand type was reduced in area by 76 per cent from 1954 to 1994. Patch density and mean patch size decreased during this time while mean nearest neighbour distance increased. Simulations of the three management scenarios for a 200‐year period projected relatively minor differences in landscape patterns among the scenarios. This is because the forest plan scenario is relatively restrictive in timber harvest and because most of the area protected in the other two scenarios does nor currently support old growth. We discuss the role of decision‐support tools such as PAYSAGE in adaptive ecosystem management and evaluate limitations of the model.

Effects of Forest Stand Structure and Composition on Red-Breasted Nuthatches and Brown Creepers

Habitat requirements of birds should be considered when planning silvicultural activities. Thus, we studied the use of forest resources by brown creepers (erthia americana) and red-breasted nuthatches (Sitta canadensis) for 1 year in 8 forest stands on the western slope of the Sierra Nevada to determine the causes of temporal and spatial patterns in resource use. Both species used stands with a diverse structure characteristic of mature mixed-conifer forests. Intensity of stand use by both creepers and nuthatches was correlated (r s = 0.81-0.86, P < 0.05) with the percent basal area of sugar pine (Pinus lambertiana) over all sample periods

Food Caching and Its Possible Origin in the Brown Creeper

Food Caching and Its Possible Origin in the Brown Creeper

Avian Use of Habitat Configurations Created by Forest Cutting in Southeastern Wyoming

Timber harvest in western forests initially interrupts large expanses of oldgrowth forest with smaller clearcuts. Although the vegetation within the remaining oldgrowth is still present and intact, there is an increase in forest edges and a reduction in the continuity of the original forest. We compared avian species composition and abundance in four pairs of sites, each pair having an uncut site and one fragmented by small clearcuts in southeastern Wyoming. Fragmented stands were interrupted with strip or patch clearcuts. The abundance of species was also compared among the habitat configurations present on these sites such as forest interiors, meadow edges and clearcuts. Of 16 bird species, Brown Creepers (Certhia americana) and Hermit Thrushes (Catharus guttatus) were the most negatively influenced by fragmentation; Pine Siskins (Carduelis pinus) were the most positively influenced by fragmentation. The distribution of birds among forest interiors and edges suggested the responses to fragmentation were not generally mirrored by preferences or avoidance of forest edges and interiors. The effect of fragmentation may result from the loss of resources from clearcutting or preferences for the type of habitat adjacent to the forest stand (meadows or clearcuts).

Animal vectors of Arceuthobiumamericanum seed in Manitoba

Long-distance dispersal of Arceuthobiumamericanum Nutt. ex Engelm. seed by animals was investigated in Grand Beach Provincial Park, Manitoba, where passerine migration routes traverse stands of dwarf mistletoe infected Pinusbanksiana Lamb. Small mammals appear to be insignificant as vectors in Manitoba as no seeds were found on any of the 193 individuals trapped. In contrast, 5.5% of 146 birds netted in 1986 and 5.1% of 59 netted in 1987 carried seed. Three species are reported carrying seed for the first time: brown creeper (Certhiaamericana), Swainson's thrush (Catharusustulatus), and red-breasted nuthatch (Sittacanadensis). Seeds were also found on five gray jays (Perisoreuscanadensis) and three dark-eyed juncos (Juncohyemalis), species for which numerous records of dwarf mistletoe seed transport already exist. Swainson's thrushes and dark-eyed juncos are potential disseminators of A. americanum seed into jack pine stands in northern Ontario and the Great Lakes States during years when seed discharge and migration overlap.

Foraging Behavior of Bark-Foraging Birds in the Sierra Nevada

Data on foraging behavior are often used for examining use of habitat and describing community structure among co-occurring species of birds using the same resource base (e.g., Johnson 1966, Eckhardt 1979, Rusterholz 1981). Differences in tree species, foliage morphology, and bark structure may influence the types of prey taken and the species of bird using the substrate (e.g., Jackson 1979, Holmes and Robinson 1981, Robinson and Holmes 1984). Elucidation of foraging behaviors and tree species preferences is important if we are to determine the role of birds in forest ecosystems, and make informed decisions regarding management of these forests. In this study we describe the use of tree species, foraging modes, and foraging substrates by a group (or guild, sensu Root 1967) of bark-foraging birds breeding in the western Sierra Nevada. A similar study on foliage insectivores was conducted previously near our study area (see Airola and Barrett 1985). The species analyzed, in order of decreasing abundance, were: Red-breasted Nuthatch (Sitta canadensis), Brown Creeper (Certhia americana), Red-breasted Sapsucker (Sphyrapicus ruber), White-headed Woodpecker (Picoides albolarvatus), Hairy Woodpecker (P. villosus), and Pileated Woodpecker (Dryocopus pileatus) (see Morrison et al. 1986). All are typical inhabitants of coniferous forests in the Sierra Nevada (Grinnell and Miller 1944). The Downy Woodpecker (Picoides pubescens) and Northern Flicker (Colaptes auratus) occurred rarely in our study area and are not analyzed herein. STUDY AREA

Morphometrics of the whiteheadMohoua albicillaon Little Barrier Island, New Zealand

Abstract We measured 95 whiteheads (Mohoua albicilla) on Little Barrier Island, including 39 of known sex. Known males were significantly heavier and larger, on average, than females, although there was some overlap. Within mated pairs the male was always larger than the female. A plot of weight against wing length or a simple sum and product of four parameters, completely separated the known males and females and allowed most other birds to be sexed. Plumage and leg colour are only partly reliable as indicators of sex. All birds classed as males from their bright white heads and shiny black legs were subsequently found to be males. All females were successfuly classed as females from their duller plumage and paler legs, but so were many males. Comparison with published measurements of whiteheads from near Wellington suggests that there is no clinal variation in size. Whiteheads are intermediate in size between brown creepers (Finschia novaeseelandiae) and yellowheads (M. ochrocephala). Males are larger t...

ARTHROPOD FOOD OF SOME FOREST-INHABITING BIRDS

AbstractThe diets of 25 species of forest-inhabiting birds were examined in California from 1962 to 1968. Coleoptera and Hymenoptera comprised the bulk of the diets. Coleopterans were, in decreasing amounts, the most common food of the three-toed woodpecker, Steller's jay, American robin, brown creeper, hairy woodpecker (both sexes), dark-eyed junco, downy woodpecker (both sexes), olive-sided flycatcher, western wood-pewee, and white-headed woodpecker (both sexes). Hymenopterans, mainly ants, were the most common food of the northern flicker, Williamson's sapsucker, red-breasted sapsucker, and acorn woodpecker. White-headed woodpecker (both sexes) also ate ponderosa-pine seeds in the fall. Hairy woodpecker (both sexes) fed on the seeds of ponderosa pine and sugar pine. Detailed estimates of foods consumed by item and volume from analyses of stomach contents of 241 specimens are presented.