Skip to main content
Advanced Search

Filters: Tags: Habitat (X) > Types: Citation (X) > Extensions: Citation (X) > Types: Journal Citation (X)

11 results (16ms)   

View Results as: JSON ATOM CSV
Sage-grouse (Centrocercus urophasianus and C. minimus) historically inhabited much of the sagebrush-dominated habitat of North America. Today, sage-grouse populations are declining throughout most of their range. Population dynamics of sage-grouse are marked by strong cyclic behavior. Adult survival is high, but is offset by low juvenile survival, resulting in low productivity. Habitat for sage-grouse varies strongly by life-history stage. Critical habitat components include adequate canopy cover of tall grasses (? 18 cm) and medium height shrubs (40?80 cm) for nesting, abundant forbs and insects for brood rearing, and availability of herbaceous riparian species for late-growing season foraging. Fire ecology of...
Distribution, movements, and habitat use of 10 wild adult razorback suckers (Xyrauchen texanus) were examined in Lake Mohave, Arizona-Nevada, from November 1994 through July 1997. Movement rates (0.00?17.35 km d?1) and ranges (x?= 39 km) were similar to those for riverine populations. All study fish returned to spawning sites used in previous years, but they also visited other spawning areas. Spawning females were significantly (P = 0.031) more active than males (480 vs. 87 m d?1) and moved substantial distances between spawning sites during peak reproduction (1?28 February). Fish became most active (m d?1, km month?1) after spawning and moved to areas known to support higher algal production. Fish were typically...
Sympatric populations of Cophosaurus texanus and Callisaurus draconoides were periodically sampled from March 1973 through April 1974 at Burro Creek, Mohave County, Arizona. Callisaurus were also sampled at Rock Valley, Nye County, Nevada. Sex ratios were skewed in favor of males in the adult Cophosaurus but were equal in both adult populations of Callisaurus. Both species became sexually mature as yearlings. Mean clutch sizes were 3.55 (+/- 0.83) for Cophosaurus, and 4.25 (+/- 1.08) and 5.07 (+/- 1.33) for Callisaurus at Burro Creek and Rock Valley respectively. Evidence of multiple clutches was exhibited by both species. Egg weight/body weight ratios for both species and clutch weight/body weight ratios for Cophosaurus...
Small aspen stands are disappearing from the landscape in the Southwest, so it is important to understand their contribution to the avian community. We sampled birds in 53 small, isolated aspen stands and 53 paired plots within the ponderosa pine forest in northern Arizona, during the 1996 and 1997 breeding seasons. Bird species richness and abundance were higher in aspen than in pine. However, bird species richness and abundance did not vary with size of the aspen patch or isolation index. In addition, direct ordination of species distributions with habitat factors suggested no distinct avian communities. This suggests that aspen stands do not harbor separate populations, but rather are locations where the regional...
To determine habitat attributes and processes suitable for the growth of Coccidioides, soils were collected from sites in Arizona, California, and Utah where Coccidioides is known to have been present. Humans or animals or both have been infected by Coccidioides at all of the sites. Soil variables considered in the upper 20 cm of the soil profile included pH, electrical conductivity, salinity, selected anions, texture, mineralogy, vegetation types and density, and the overall geomorphologic and ecological settings. Thermometers were buried to determine the temperature range in the upper part of the soil where Coccidioides is often found. With the exception of temperature regimes and soil textures, it is striking...
thumbnail
In recent years, the demand has grown for information on how to conserve bat populations in forested ecosystems. Many researchers have responded with studies of bats in forests, but few have studied bat communities in arid-adapted forest types, such as pinyon-juniper woodlands, which are widespread and abundant throughout the west. In this study, I evaluated the relative use and importance of pinyon-juniper woodlands to bats in west-central New Mexico by comparing bats captured in pinyon-juniper woodlands with those captured in ponderosa pine forest. I compared species richness and relative abundance of bats captured in these vegetation types and evaluated the relative importance of each based on its use as reproductive...
June sucker (Chasmistes liorus) spawned in the Provo River, Utah, over a 2-wk period in early June during both 1987 and 1988. Emergent larvae emigrated from the river to Utah Lake over a 2- to 3-wk period. Drift into the lake peaked between 1200 and 0400. During daylight hours, emergent larvae tended to occur in pools. Peak emergence of larval drift was approximately 1.2 larvae/m3 during late June in 1987 and 1988. Recruitment failure of June sucker is not due to reproductive failure. Published in Western North American Naturalist, volume 54, issue 4, in 1994.
The morphologically unique and endangered humpback chub, Gila cypha, is found in canyon-bound reaches of the Colorado River and its tributaries. Now limited to six isolated reproducing populations, this species is believed to have been once distributed over a large portion of the mainstem river. Because the species inhabits remote canyon areas, little is known about its spawning ecology. The largest remaining population occurs in the lower Little Colorado River (LCR) near Grand Canyon, where we conducted a three-year study of spawning ecology during spring (March-June) 1993?1995. We analyzed seasonal patterns of movement, population density, relative condition, spawning scores, and frequency of ripe condition and...
Detailed empirical models predicting both species occurrence and fitness across a landscape are necessary to understand processes related to population persistence. Failure to consider both occurrence and fitness may result in incorrect assessments of habitat importance leading to inappropriate management strategies. We took a two-stage approach to identifying critical nesting and brood-rearing habitat for the endangered Greater Sage-Grouse (Centrocercus urophasianus) in Alberta at a landscape scale. First, we used logistic regression to develop spatial models predicting the relative probability of use (occurrence) for Sage-Grouse nests and broods. Secondly, we used Cox proportional hazards survival models to identify...
Recent energy development has resulted in rapid and large-scale changes to western shrub-steppe ecosystems without a complete understanding of its potential impacts on wildlife populations. We modeled winter habitat use by female greater sage-grouse (Centrocercus urophasianus) in the Powder River Basin (PRB) of Wyoming and Montana, USA, to 1) identify landscape features that influenced sage-grouse habitat selection, 2) assess the scale at which selection occurred, 3) spatially depict winter habitat quality in a Geographic Information System, and 4) assess the effect of coal-bed natural gas (CBNG) development on winter habitat selection. We developed a model of winter habitat selection based on 435 aerial relocations...
Prairie dog (Cynomys spp.) populations have been reduced by 98% compared to historical levels because of widespread poisoning, habitat loss, recreational shooting, and outbreaks of sylvatic plague (Yersinia pestis). Our objectives were to identify habitat correlates of Gunnison's prairie dog (C. gunnisoni) colonies and to develop a predictive logistic regression model to identify potential reintroduction sites for this species. During 2000 and 2001, we examined habitat features at 50 Gunnison's prairie dog colonies and 50 paired random sites in northern Arizona, USA. When compared to random sites, Gunnison's prairie dog colonies had deeper soils, less variability in slope, and less rock ground cover. Our results...
    map background search result map search result map Use of pinyon-juniper woodlands by bats in New Mexico Use of pinyon-juniper woodlands by bats in New Mexico