Treesearch

The Utah Avian Conservation Strategy (Parrish et al. 2002) published by the Utah Partners in Flight (UPIF) Program ranked a total of 24 habitat types and 231 bird species with respect to their need for conservation action. The 24 habitat categories were grouped within five major categories, Riparian, Shrublands, Grassland, Forest, and a collection of additional categories unique to conservation planning efforts in Utah. Shrublands comprise the most abundant of these habitat categories, with sagebrush communities (2.9 million ha) second only to greasewood/halogeton dominant shrublands (5.5...

Coastal scrub habitats in California are threatened by habitat loss, fragmentation, and degradation. Local and statewide declines have been observed in several birds that breed in coastal scrub, most notably the California Gnatcatcher (Polioptila californica; Atwood 1993), but also include more common species such as the Whitecrowned Sparrow (Zonotrichia leucophrys; Trail and Baptista 1993; Sauer et al. 2001; Point Reyes Bird Observatory [PRBO], unpubl. data). While Breeding Bird Survey data can be used to track population trends over larger scales (Sauer et al. 2001), they are not always...

We investigated densities of four common species, Wrentit (Chamaea fasciata), Spotted Towhee (Piplio erythrophthalmus), Bewick’s Wren (Thryomanes bewickii), and Orange-crowned Warbler (Vermivora celata) in relation to trail width in chaparral habitats of Mt. Tamalpais, Marin County, California. Point count sampling stations were assigned to one of three trail width groups—thin (≤2 m), medium (2.1-4 m), and wide (>4 m). We found a marginally significant (P < 0.1) negative effect of trail width on the density of Spotted Towhee when thin trails were compared to medium/wide trails. For the...

We performed bird point counts monthly March-June 2001 and bi-monthly August 2001-February 2002 across a sampling grid of 35 points along the west edge of Salton Sea. We found that landbird species diversity (both in numbers of species, and numbers per species) was dependent on proximity to the sea. Diversity was at a maximum nearest the shore, and was significantly lower farther from the shore. Creosote bush (Larrea tridentata) and alkali goldenbush (Isocoma acradenia) are the co-dominant plants on the study site, and vary widely in their horizontal and vertical structure. After measuring...

Habitat associations were determined for five species of songbirds breeding in sagebrush habitat of the South Okanagan and Similkameen valleys, British Columbia. We examined the relative importance of plant species versus “total forbs” and “total grasses” at a local level (<100 m) with point counts and vegetation survey data collected at 245 points. Logistic regression models showed that individual plant species were often more important than variables that grouped species. Habitat associations varied for each species. Brewer's Sparrow (Spizella breweri) was associated with parsnipflowered...

Predation is the predominant cause of nest failure for the Brewer's Sparrow (Spizella breweri breweri), a provincially red-listed shrub-steppe species that has experienced significant declines throughout most of its range. We monitored Brewer’s Sparrow nests and conducted an artificial nest experiment, in the South Okanagan Valley, British Columbia (B.C.), to investigate factors associated with nest predation. Avian predation of artificial nests was higher when nests were placed in smaller shrubs, set out earlier in the season and when corvid numbers were high. Predator imprints on clay...

Wetland areas have been drastically reduced through the Pacific Flyway and the Sonoran Desert, with severe consequences for avian populations. In the Colorado River delta, wetlands have been reduced by 80 percent due to water management practices in the Colorado River basin. However, excess flows and agricultural drainage water has restored some areas, providing habitat for several sensitive species such as the Yuma Clapper Rail (Rallus longirostris yumanensis). This has sparked community interest to explore different scenarios for the restoration of bird habitat. Three community based...

We examined the distribution and abundance of hummingbirds at three study sites in southeastern Arizona, where over 8,000 individuals of twelve species were banded. Banding occurred at two sites in the early 1990s and is currently active at the third. Anna’s (Calype anna), Black-chinned (Archilochus alexandri), and Rufous (Selasphorus rufus) Hummingbirds were the most abundant species. A massive southbound fall migration occurred at the study sites with fewer hummingbirds moving northward in spring. The large numbers of migrants were spaced over time within seasons, and the timing of peak...

Sagebrush ecosystems occupy over 62,000,000 ha of the western US. However, they have been degraded or completely eliminated by agricultural conversion, overgrazing by domestic livestock, invasion of exotic plants, expansion of pinyon and juniper woodlands, uncharacteristic wildfires, and fragmentation. This habitat loss has led to an increasing number of special status species, including 630 plant and animal species of conservation concern. In this paper, we focus on the 22 taxa of sagebrush associated birds that are priorities in Partners in Flight Bird Conservation Plans. These range...

Resource managers face the challenge of understanding how numerous factors, including fire and fire suppression, influence habitat composition and animal communities. We summarize information on fire effects on major vegetation types and bird/fire relations within the maritime Pacific Northwest, and pose management related questions and research considerations. Information on how fire affects birds is limited for the maritime Pacific Northwest, even though fire is an essential process within natural vegetation communities throughout the region. We describe fire regimes, vegetation successio...