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1.
This paper describes features of the breeding bird population of a Great Basin ancient bristlecone pine stand on Wheeler Peak in White Pine County, east central Nevada. The bird population was determined by spot-mapping methods on a 20-ha plot during June and July 1981. The density of breeding birds was 82 pairs per 40 ha. Fourteen species were territorial. The most abundant species were the Dark-eyed Junco, Mountain Chickadee, Mountain Bluebird, and Townsend’s Solitaire. Other common breeding species included the Cassin’s Finch, Yellow-rumped Warbler, Pine Siskin, and Dusky Flycatcher. There were 410 individual breeding birds per km 2 . When expressed as standing crop biomass, the Townsend’s Solitaire was the predominant species, followed by the Dark-eyed Junco, American Robin, Mountain Bluebird, and Northern Flicker. Total standing crop biomass was 95 g/ha. None of the breeding birds were restricted to the bristlecone pine stand. The structure of the breeding bird community in the bristlecone pine forest compared best to those of the Rocky Mountain and Northern Boreal forest regions.  相似文献   

2.
In northern areas of their expanded range, information on Merriam's turkeys ( Meleagris gallopavo merriami ) is lacking, specifically pertaining to wintering behavior and factors associated with winter habitat selection. Forest managers need detailed quantification of the effects of logging and other management practices on wintering habitats needed by Wild Turkeys and other wildlife. Therefore, we examined winter habitat selection patterns within ponderosa pine ( Pinus ponderosa ) forests and determined factors associated with use of farmsteads by Merriam's turkeys in the southern Black Hills, South Dakota. We radio-marked 86 female Merriam's turkeys (70 adults and 16 yearlings) and monitored them during winter (1 December–31 March), 2001–2004. Female Wild Turkeys used recently burned pine forest less than expected but selected farmsteads and stands of mature ponderosa pine ( 22.9 cm diameter at breast height [DBH] trees) for foraging sites. Within forests, female Wild Turkeys selected foraging sites with less understory vegetation and visual obstruction, and larger-diameter ponderosa pine. Ponderosa pine seed abundance varied among years, and pine seeds were most abundant in stands of 30–35 cm DBH with basal area of 22–28 m2 ? ha–1. Abundance of pine seeds may have influenced use of farmsteads by Wild Turkeys, more so than ambient temperatures or snow depth. In the southern Black Hills, management should emphasize open- to mid-canopy and mature-structural-stage pine stands, where seed production was greatest. During winters when mast from pine is unavailable, farmsteads likely provide nutritional supplementation and may be important for maintaining Merriam's turkey populations.  相似文献   

3.
Seventy-four species of montane breeding birds were evaluated for their vulnerability to extirpation in the Great Basin. Although none of these species are endemic to the Great Basin, the montane island system results in a unique pattern of species associations. Loss of species from these montane communities could be indicative of region wide habitat degradation. I ranked susceptibility to extirpation based on seven biological variables: geographic range, population size, reproductive potential, susceptibility to cowbird parasitism, migratory status, and diet specialization. Each variable was weighted equally in its contribution to vulnerability, and scores were the sum of trait scores for each species. Different suites of life-history traits led to similar vulnerabilities. The following 10 montane bird species were categorized as most vulnerable to extirpation from the Great Basin, listed as most to least vulnerable: Olive-sided Flycatcher ( Contopus borealis ), Painted Redstart ( Myioborus pictus ), Hammond's Flycatcher ( Empidonax hammondii ), Veery ( Catharus fuscescens ), Whip-poor-will ( Caprimulgus vociferus ), Lincoln's Sparrow ( Melospiza lincolnii ), Black-backed woodpecker ( Picoides arcicus ), Three-toed Woodpecker ( P. tridactylus ), Himalayan Snowcock ( Tetraogallus himalayensis ), and Nashville Warbler ( Verminvora ruficapilla ). Species of similar vulnerability scores often were dissimilar in threats related to their vulnerability. No taxonomic patterns in vulnerability were found. This type of analysis should be used proactively to identify vulnerable species or populations and to set priorities for research management.  相似文献   

4.
Two hundred forty-one species of birds have been identified from northern Black Mesa, Arizona. This region's avifauna was poorly known until the late 1970s when large-scale coal mining began. Vegetation of the region is predominantly Great Basin desert scrub, pinyon-juniper woodland, and mixed-conifer woodland. The latter vegetation supports an assemblage of isolated montane bird species unique to the region. Numerous environmental changes have recently affected the bird life of Black Mesa. These include large-scale type conversions (pinyon-juniper clearing and surface mining), pond construction, and establishment of exotic vegetation.  相似文献   

5.
Bird species density, diversity, and species richness in relation to habitat and seasonal variations were studied in the Betatakin Canyon area of Navajo National Monument, Arizona. The two most prominent habitat types are a riparian forest deep in the canyon bottom and a mature pinyon-juniper woodland on the mesas and slopes above the canyon. One hundred thirty-five species of birds were encountered during the study and recorded by season and habitat. The avifauna assemblages demonstrate definite habitat selection into groups associated with the riparian and pinyon-juniper woodland communities. Diversity, density, and species richness were greatest in the riparian habitat during the spring and summer months. The differences in bird community composition were greater between seasons than between habitats. Pinyon pine and Gambel oak were highly selected as perch sites in the pinyon-juniper and riparian areas, respectively.  相似文献   

6.
Bird species density, diversity, and species richness in relation to habitat and seasonal variations were studied in the Betatakin Canyon area of Navajo National Monument, Arizona. The two most prominent habitat types are a riparian forest deep in the canyon bottom and a mature pinyon-juniper woodland on the mesas and slopes above the canyon. One hundred thirty-five species of birds were encountered during the study and recorded by season and habitat. The avifauna assemblages demonstrate definite habitat selection into groups associated with the riparian and pinyon-juniper woodland communities. Diversity, density, and species richness were greatest in the riparian habitat during the spring and summer months. The differences in bird community composition were greater between seasons than between habitats. Pinyon pine and Gambel oak were highly selected as perch sites in the pinyon-juniper and riparian areas, respectively.  相似文献   

7.
We determined temporal and spatial differences in abundance and habitat use by small mammals in southeastern Utah as part of an effort to enhance management of the Mexican Spotted Owl ( Strix occidentalis lucida ), listed by the federal government as threatened. Woodrats ( Neotoma spp.) were captured only in canyons and most frequently in the pinyon-juniper ( Pinus edulis-Juniperus osteosperma ) vegetation type. White-footed mice ( Peromyscus spp.) were found in a variety of vegetation types in both canyons and mesas. The deer mouse ( P. maniculatus ) was generally the most frequently captured species among vegetation types. We found seasonal and yearly differences in relative abundance of each small mammal species. Our data suggest that the pinyon-juniper vegetation type within canyons is an important component of Mexican Spotted Owl habitat.  相似文献   

8.
We compared winter (December, January, and February) and early spring (March and April) bird communities among 4 successional stages that included grassland, shrubsteppe, juniper-shrubsteppe, and old-growth juniper woodland in central Oregon. Birds were surveyed monthly from December through April in 1998/1999 and 1999/2000 using the point count method to estimate relative abundance of birds (individuals ? transect –1 year –1 ). We used distance sampling to correct for potential bias in estimating abundance and density among successional stages. A total of 4513 birds (32 species) were detected. Relative abundance of total birds (all species combined) was similar in the juniper-shrubsteppe and old-growth woodland (48.7 and 48.9 individuals ? transect –1 , respectively) but 6 times greater than in the grassland and shrubsteppe (8.0 and 7.7 individuals ? transect –1 , respectively) during the 5-month period. Total density of birds was greater in old-growth juniper woodland and juniper-shrubsteppe than in grassland or shrubsteppe. However, median bird species richness in 1998/1999 was highest in grassland and lowest both in shrubsteppe and juniper-shrubsteppe, and in 1999/2000 it was highest in shrubsteppe and lowest in juniper-shrubsteppe and oldgrowth juniper woodland. American Robins and Townsend's Solitaires were the most abundant species in junipershrubsteppe and old-growth juniper woodland during the winter months. Sage Sparrows and Horned Larks were the most abundant species in shrubsteppe during winter, and Horned Larks were most abundant in grasslands during the early spring transition period prior to nesting. Our results indicate that a different suite of species use these successional stages during the nonbreeding season. If avifauna conservation is a part of long-term management goals, a broad range of successional stages should be maintained on the landscape to provide habitat for a variety of avian species throughout the year.  相似文献   

9.
《Journal of Natural History》2012,46(11-12):661-674
The aim of this study was to investigate the seasonal population fluctuation of orthopteran assemblages and determine the spatial distribution of the most abundant species of Orthoptera among two habitats in Greece. A 2-year study was performed in a lowland area and in a mountain grassland area. The family of Acrididae represented almost 75% of the total orthopteran relative abundance in both sampling areas. Dociostaurus maroccanus and Chorthippus bornhalmi were found to be the most abundant species in the lowland and the mountain sampling stations, respectively. Most populated species were spatially aggregated in the lowland station, whereas the abundant species were found to be distributed either aggregately or randomly among sampling units in the mountain area. Shannon–Wiener index estimate was higher for the lowland in 2007 than for the mountain, whereas the opposite was found in 2008. The factors affecting the population dynamics of Orthoptera are discussed.  相似文献   

10.
I surveyed 34 meadows in California and Oregon to count Lincoln's Sparrows ( Melospiza lincolnii alticola ) and to identify habitat features that might influence their local, insular occurrence. Lincoln's Sparrows were most common in wet meadows with little damage by grazing. Singing males were concentrated in flooded or boggy areas near meadow edges, where pines ( Pinus sp.) provided elevated perches for singing and vigilance. Patches of willows ( Salix sp.) were often present nearby. Numbers of male Lincoln's Sparrows were strongly and negatively correlated with abundance of sympatric Song Sparrows ( M. melodia fisherella ). Lincoln's Sparrows breeding in montane meadows are potentially vulnerable to local extirpation because of their insular distribution, low population density, and fluctuating habitat conditions. Heavy damage from livestock grazing drastically increases the probability of local extirpation.  相似文献   

11.
12.
Nest-boxes were monitored from 1988 to 1992 on 5 grids in the pinyon-juniper ( Pinus-Juniperus ) woodlands of the White and Inyo Mountains, California, to determine breeding phenology and productivity of cavity-nesting birds, and characteristics of used and non-used nest-boxes. We found a total of 112 nests of 6 species. Bewicks Wrens ( Thryomanes bewicki i; 64 nests), Mountain Chickadees ( Poecile gambeli ; 18), Ash-throated Flycatchers ( Myiarchus cinerascens ; 12), and Juniper Titmice ( Baeolophus ridgwayi ; 11) were the most common species utilizing the boxes. Nest phenology and numbers of young were similar to values reported elsewhere in the literature for the species, although nesting success for Mountain Chickadees appeared lower in our study. Chickadees were associated with relatively dense, mature vegetation on southern slopes. Juniper Titmice used areas with tall juniper shrubs and generally sparse vegetation. Bewicks Wrens used areas with short trees, sparse vegetation, and many stumps. Nest-boxes were underutilized (< 15% use) by most species relative to their availability and relative to detected abundances of the species. We suggest that nest-boxes can provide valuable breeding biology information and can potentially increase the productivity of rare and cavity-limited species.  相似文献   

13.
We examined abundance and flight periodicity of 3 predators of bark beetles (Coleoptera: Curculionidae, Scolytinae), Temnochila chlorodia (Mannerheim) (Coleoptera: Trogositidae), Enoclerus sphegeus (Fabricius) (Coleoptera: Cleridae), and E. lecontei (Wolcott) (Coleoptera: Cleridae), across an elevational gradient of ponderosa pine ( Pinus ponderosa Lawson) forests in north central Arizona. Predator populations were estimated at 10 sites in each of 3 elevation bands (low: 1600&ndash;1736 m; mid: 2058&ndash;2230 m; high: 2505&ndash;2651 m) for 3 years (2004&ndash;2006) using pheromone-baited funnel traps targeting 3 primary bark beetle species. We also investigated how predator abundance and flight seasonality related to those of 5 bark beetle species: Ips pini (Say), I. lecontei Swaine, Dendroctonus frontalis Zimmermann, D. brevicomis LeConte, and D. adjunctus Blandford. Temnochila chlorodia was most abundant in the low- and mid-elevation bands, whereas E. sphegeus was most abundant in the high-elevation band. Enoclerus lecontei showed no consistent elevational trend in abundance. Within each elevation band, changes in annual abundance of pooled predator species tracked shifts in abundance of pooled bark beetle species. In general, predator flight initiation coincided with or closely followed bark beetle flight initiation in the spring, but predator flight terminated before flight activity ended for most bark beetle species in the fall. In addition, the ratio of prey to predators was lowest in the summer and highest in the fall. This suggests that all bark beetle species examined may be provided temporal escape from their predators in the fall. For all 3 predator species, the pheromone-baited trap targeting D. brevicomis was less attractive than the pheromone-baited traps targeting I. pini and I. lecontei.  相似文献   

14.
The overwhelming majority of bird species in the Great Basin region are found in riparian habitats. However, most previous research on the impact of change in habitat condition through degradation on these bird communities failed to account for the large intersite differences, in both habitat type and extent of degradation. We examined songbird communities in 4 riparian habitat types (meadows, willow-birch-, and aspen-dominated forest stands) during summers 1994 (last year of a 7-yr drought) and 1995 (following the 6th wettest winter recorded) in the Toiyabe Mountain Range of central Nevada. Habitat degradation significantly influenced bird species richness in riparian areas, but the impact was dependent upon habitat type. While meadow bird communities were affected adversely by habitat degradation, with significant drops in species richness on degraded sites, bird species richness in forested riparian habitats was consistently greater on degraded sites. Data for the 6 most common species seen during our study indicated that degradation may have influenced distribution of American Robins ( Turdus migratorius ) and Yellow Warblers ( Dendroica petechia ), but habitat type was the best predictor of abundance for House Wrens ( Troglodytes aedon ), Red-naped Sapsuckers ( Sphyrapicus nuchalis ), Warbling Vircos ( Vireo gilvus ), and Brewer's Blackbirds ( Euphagus cyanocephalus ). Avian species diversity in meadow habitats may be linked to moisture levels during specific times of the year. Diversity increased during the pre-migratory period of the dry year (1994) when compared with that of the breeding season, but was unchanged in the wet year (1995).  相似文献   

15.
We examined relationships between high-elevation sagebrush ( Artemisia spp.) steppe habitats altered by prescribed fire and western juniper ( Juniperus occidentalis ) encroachment on breeding distributions of Brewer's Sparrows ( Spizella breweri ), Vesper Sparrows ( Pooecetes gramineus ), Green-tailed Towhees ( Pipilo chlorurus ), and Sage Thrashers ( Oreoscoptes montanus ) on Steens Mountain in southeastern Oregon. In 2000 we conducted fixed-radius point count surveys at 172 sites encompassing burned and unburned sagebrush habitat and a range of juniper densities. For each bird species we developed habitat models using local variables measured in the field and landscape variables derived from remotely sensed data. Akaike's Information Criterion (AIC c ) was used to select the best-approximating model from a suite of a priori candidate models. Brewer's Sparrows, Sage Thrashers, and Green-tailed Towhees were positively related to increasing local sagebrush cover or percent sagebrush in the landscape, whereas Vesper Sparrows were negatively associated with sagebrush cover and positively related to increases in sagebrush fragmentation at local and landscape scales. Including a measure of juniper encroachment substantially improved models for all species in the analysis. Green-tailed Towhees showed a curvilinear response to the amount of juniper in the landscape. All other species showed a strong negative relationship with juniper. Our results indicate that, although changes in sagebrush habitat associated with fire had a negative influence on sagebrush birds, juniper encroachment due to fire suppression also impacted this high-elevation sagebrush bird community.  相似文献   

16.
Ground Beetles from Rotger's collection of Colorado specimens have been identified, principally by the author, and a faunal list of 161 species from 80 localities is presented. The list includes 35 species not previously recorded from Colorado. Comparisons are made with Armin's (1963) carabid list from Boulder County and the diversity of species along transects through four elevational zones from the plains to the alpine.  相似文献   

17.
Habitat use and selection by Merriam's Wild Turkeys ( Meleagris gallopavo merriami ) in Wasco County, Oregon, was studied during 1981-82. This turkey population selectively used forested cover types (such as ponderosa pine-Douglas-fir-oak, ponderosa pine-oak) characterized by a variety of structural features, species, and age classes. The population used single species forested cover types (oak, ponderosa pine) less than expected, used nonforested cover types in proportion to their availability, and avoided forested cover types with structure simplified by logging activities. The four age and sex classes had large seasonal home ranges ( ̄x = 1,615 ha); the smallest home ranges were exhibited by adult males in winter and the largest were shown by subadult males in fall. In most instances, turkeys used cover types as they were available. We suggest that structural complexity of vegetation, both within and among cover types, is an important component of habitat for Merriam's Wild Turkeys that should be considered in the evaluation of potential release sites and in habitat management plans.  相似文献   

18.
We analyzed the prevalence and intensity of chewing lice on two neotropical species of Turdus and identified morphological parameters of birds influencing louse population dynamics. The study was conducted in southernmost Rio Grande do Sul state (RS), Brazil, between July 2009 and June 2010. Chewing lice were collected by dust-ruffling. The prevalence of chewing lice on both species of Turdus was high. Chewing lice from both species of Turdus exhibit similar composition and distribution patterns. However, chewing lice were more abundant on Turdus rufiventris, whereas species richness was higher on Turdus amaurochalinus. Myrsidea and Brueelia were the most prevalent and abundant genera on both host species in all seasons of the year. A predominance of chewing louse females and adults was observed. Aggregated distributions were observed. Body length was the only morphological parameter correlated with louse abundance, suggesting that specimens with a larger body have a higher abundance of lice.  相似文献   

19.
20.
A two-year study of the rare vascular plants of the Idaho National Engineering Laboratory generated new data on the abundance, distribution, and habitat features of eight taxa presently under review at either the federal or state level, or recently proposed for such review. Astragalus ceramicus Sheld. var. apus Barneby is common on the INEL and adjacent areas and will be recommended for removal from further consideration at the federal level and placed on Idaho's Federal Watch List. Coryphanta missouriensis (Sweet) Britt. & Rose is common throughout east central Idaho, but will be recommended for retainment on the State Watch List. Gymnosteris nudicaulis (H. & A.) Greene and Oxytheca dendroidea Nutt. are also recommended for retention on the State Watch List. Four taxa not previously known to occur in Idaho or not known from the southeastern part of the state ( Astragalus gilviflorus Sheld., Astragalus kentrophyta Gray var. jessiae (Peck) Barneby, Gilia polycladon Torr., and Lesquerella kingii S. Wats. var. cobrensis Roll. & Shaw) were encountered and evaluated with reference to current or potential threats, and are recommended for placement on Idaho's State Watch List. &nbsp;&nbsp;&nbsp;  相似文献   

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