Red Crossbills (Fringillidae: Loxia curvirostra), irruptive finches which feed on conifer seeds, have long presented an evolutionary conundrum. Variable morphology and vocalizations in the species can be classified into several flight call types, which may be discrete lineages. The key conifer hypothesis suggests that each type diverged by specializing on...
North American bird populations have declined throughout the past half century. The majority of studies quantifying these declines have focused on spring and summer breeding birds; not the season of scarcity, winter. We re-surveyed 7 large study plots in Douglas fir forests initially surveyed in winter during the late 1960s...
The evolutionary arms race between predators and prey has led to a diverse set of interactions between species. Prey have developed an array of behaviors designed to reduce their risk of predation. Among those strategies, mobbing is a paradoxical behavior where prey actually approach predators, often in large multi-species flocks....
Human alteration of natural landscapes leads to biodiversity loss, often from a combination of area effects and fragmentation effects. Smaller habitat patches support fewer species than large ones and incur additional consequences from isolation. Efforts to preempt biodiversity loss from insular habitat fragments are complicated by individualistic species responses and...
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W. Douglas Robinson
Human alteration of natural landscapes leads to biodiversity loss
Models of a species’ distribution and models of a species’ spatially explicit density are valuable tools for conservation. They allow researchers to estimate changes in distributions, densities, and populations, based on changing environmental conditions. To trust such estimates, however, the quality of models is exceedingly important. Model performance can be...
Monitoring mercury (Hg) exposure in avian populations is critical to understanding the effects of this neurotoxin. Avian Hg exposure is commonly evaluated by measuring Hg concentrations in internal tissues, blood, and feathers. Feathers are a popular sampling matrix due to ease of sampling and limited stress to birds. However, it...
Birds perform valuable ecological functions and are useful environmental indicators. Avian distributions and diversity are predicted to change over the next 50 years. Little information exists on the role of local and regional conditions in fluctuations of avian communities over time. Historic datasets present a legacy of information that helps...
Fire is an important disturbance mechanism in big sagebrush (Artemisia
tridentata) communities, yet little is known about wildlife population dynamics during
post-fire habitat succession. I estimated the abundance of small mammals and birds in
relation to fire history in mountain big sagebrush (A.t. spp. vaseyana) communities on the
Sheldon National...
Volcanism is an agent of major disturbance in many parts of the world. While the effects of volcanic disturbance are fairly well-known among some groups of species, few studies have been performed in bird communities. Likewise, few studies have attempted to compare how communities in temperate and tropical biomes respond...
Greater sage-grouse (Centrocercus urophasianus), a sagebrush obligate species, has contracted in extent by nearly half its original distribution. This is primarily due to habitat loss and degradation over the past 150 years. During winter, sage-grouse depend completely on sagebrush habitat for food and cover, yet sage-grouse winter ecology has been...