Publications

Ernpidonax trailIll extirnus is one of several recognized subspecies of the Willow Flycatcher (Unitt 1987, Browning 1993), a neotropical migrant that breeds across much of North America. This southwestern race is a riparian obligate, nesting in dense patches of willow (Salix sp.), willow-cottonwood (Populus sp.), or other similarly structured habitats. In some areas of the Southwest, it...

The timing of song development in suboscines, in which song appears not to be learned from other adults is poorly known. The Willow Flycatcher (Empidonax traillii) is a suboscine with a primary song typically referred to as fitz-bew. I report here an instance of very early singing by a 6-8-wk-old Willow Flycatcher, which sang in an aggressive context in response to a recording of adult...

Mid- to late-Holocene vegetation change from a remote high-desert site was reconstructed using plant macrofossils and pollen from 9 packrat middens ranging from 0 to 5400 yr in age. Presettlement middens consistently contained abundant macrofossils of plant species palatable to large herbivores that are now absent or reduced, such as winterfat (Ceratoides lanatd) and ricegrass (Stipa...

A physical model was developed to explain threshold friction velocities u*t for particles of the size 60a??120 I?m lying on a rough surface in loose soils for semiarid and arid parts of the United States. The model corrected for the effect of momentum absorption by the nonerodible roughness. For loose or disturbed soils the most important parameter that controls u*t is the aerodynamic...

White-faced Ibis (Plegadis chihi) eggs collected in 1996 at Carson Lake, Nevada, showed no decrease in p,p′-DDE (DDE) concentrations from levels in 1985 and 1986 which is contrary to DDE patterns shown for most avian species. An estimated 40-45% of the population was adversely affected by DDE in 1985, 1986, and 1996 with a probable net loss of about 20% of the expected productivity. One...

Long-term limnological data from the four largest lakes in Yellowstone National Park (Yellowstone, Lewis, Shoshone, Heart) are used to characterize their limnology and patterns of temporal and spatial variability. Heart Lake has distinctively high concentrations of dissolved materials, apparently reflecting high thermal inputs. Shoshone and Lewis lakes have the highest total SiO2...

Previous results of fecal analysis from the Yellowstone area and the known abilities of grizzly bears Ursus arctos to acquire and digest tissue from vertebrates suggested that grizzlies in this ecosystem obtained substantial energy from ungulates. This issue was addressed using observations from radio-marked grizzly bears, 1977–1992. Ungulates potentially contributed the majority of...

Wilderness is vital to the conservation of wildlife species that are prone to conflict with humans and vulnerable to human-caused mortality. These species tend to be large and are often carnivorous. Such animals are typically problematic for humans because they kill livestock and, occasionally, humans, and cause inordinate damage to crops. The vulnerability of large herbivores and...

Whitebark pine seeds Pinus albicaulis are an important food of grizzly Ursus arctos horribilis bears wherever whitebark pine is abundant in the contiguous United States of America; availability of seeds affects the distribution of bears, and the level of conflict between bears and humans. Almost all of the seeds consumed by bears are excavated from middens where red squirrels...

Moriarty et al. (1986) used field data to conclude that DDE decreased the size or altered the shape of avian eggs; therefore, they postulated that decreased eggshell thickness was a secondary effect because, as a general rule, thickness and egg size are positively correlated. To further test this relationship, the present authors analyzed data from eggs of captive American kestrels...

Identification of relationships among geographically distinct populations of migratory species can provide an understanding of breeding and natal philopatry, migration pathways, and population mixing during winter. We used random amplified polymorphic DNA (RAPD) analyses to search for markers specific to difficult‐to‐differentiate shorebird species (e.g. long‐billed dowitcher Limnodromus

In this article the authors used a nonparametric discriminant function in a supervised classification of Landsat Thematic Mapper satellite imagery of a ~240,000-ha semi-arid region in the Snake River Plains, southwestern Idaho. First, agriculture pixels were classified by distance from the soil baseline and water pixels by the thermal band value. Next, successive nonparametric...