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Reproduction of black-crowned night-herons related to predation and contaminants in Oregon and Washington, USA Reproduction of black-crowned night-herons related to predation and contaminants in Oregon and Washington, USA

We studied reproductive characteristics of Black-crowned Night-Herons (Nycticorax nycticorax) at four colonies in south central Washington and one colony in north central Oregon in 1991. Nest success, adjusted using the Mayfield method, was significantly different between colonies and ranged from 12-84% to hatching and 12-73% to 14 days post-hatching. The mean number of young surviving...
Authors
L. J. Blus, Barnett A. Rattner, M. J. Melancon, Charles J. Henny

Population structure of red-cockaded woodpeckers (Picoides borealis) in south Florida: RAPDs revisited Population structure of red-cockaded woodpeckers (Picoides borealis) in south Florida: RAPDs revisited

Six south Florida populations of the endangered red-cockaded woodpecker (Picoides borealis) were sampled to examine genetic diversity and population structure in the southernmost portion of the species' range relative to 14 previously sampled populations from throughout the species range. Random amplified polymorphic DNA (RAPD) analyses were used to evaluate the populations (n= 161...
Authors
Susan M. Haig, R. Bowman, Thomas D. Mullins

Effects of cutting time, stump height, parent tree characteristics, and harvest variables on development of bigleaf maple sprout clumps Effects of cutting time, stump height, parent tree characteristics, and harvest variables on development of bigleaf maple sprout clumps

In order to determine the effects of stump height, year of cutting, parent-tree size, logging damage, and deer browsing on bigleaf maple (Acer macrophyllum) sprout clump development, maple trees were cut to two stump heights at three different times. Stump height had the greatest impact on sprout clump size. Two years after clearcutting, the sprout clump volume for short stumps was...
Authors
J. C. Tappeiner, J. Zasada, D. Huffman, B. Maxwell

Can shrub cover increase predation risk for a desert rodent? Can shrub cover increase predation risk for a desert rodent?

Previous research indicates that predation risk may influence activity patterns, habitat partitioning, and community structure of nocturnal desert rodents. Shrub microhabitat is typically considered safer than open microhabitat for these small mammals. We investigated predation risk for Townsend's ground squirrels (Spermophilus townsendii), which are diurnal desert rodents that detect...
Authors
Robert L. Schooley, Peter B. Sharpe

Complete migration cycle of golden eagles breeding in northern Quebec Complete migration cycle of golden eagles breeding in northern Quebec

Radio tracking via satellite was initiated to study the year-round movements of Golden Eagles(Aquila chrysaetosc anadensis) breeding on the east coast of Hudson Bay, Quebec. In June and August 1992, six Golden Eagles(five adults and one juvenile) were marked, three of which completed their year-round movements. The eagles left their breeding area in mid- to late October and migrated to...
Authors
Serge Brodeur, R. DeCarie, D.M. Bird, Mark R. Fuller

Morphological plasticity following species-specific recognition and competition in two perennial grasses Morphological plasticity following species-specific recognition and competition in two perennial grasses

Morphological characteristics and biomass allocation of two perennial grasses, Pseudoroegneria spicata (Pursh) A. Löve ssp. spicata (bluebunch wheatgrass) and Agropyron desertorum (Fisch. ex Link) Schult. (crested wheatgrass), were compared under different competition and nutrient treatments. The competitive responses of two plants grown in containers under field conditions were assessed...
Authors
Elisabeth Huber-Sannwald, David A. Pyke, M. M. Caldwell

Distribution of nearshore macroinvertebrates in lakes of the Northern Cascade Mountains, Washington, USA Distribution of nearshore macroinvertebrates in lakes of the Northern Cascade Mountains, Washington, USA

During the summer of 1949 studies were conducted at Princeton, New Jersey, to determine the effects on wildlife of DDT used in the control of Dutch elm disease. Direct mortality was determined by intensive search for dead birds after spraying. Twenty-six songbirds, one bat, and one gray squirrel were found. Of 11 dead birds from a study area of approximately 20 acres only one was an...
Authors
Robert L. Hoffman, W.J. Liss, Gary L. Larson, E. Deimling, G.A. Lomnicky

Shorebird use of South Carolina managed and natural coastal wetlands Shorebird use of South Carolina managed and natural coastal wetlands

While many migrating and wintering shorebird (Charadriiformes) species face declines in quality and quantity of natural stopover sites, diked wetlands managed for shorebirds may provide supplemental habitat. We describe an integrative shorebird-waterfowl management strategy used at Tom Yawkey Wildlife Center on South Island, South Carolina, during 3 winter-spring seasons (1991-93). We...
Authors
Louise M. Weber, Susan M. Haig

Microenvironments and microscale productivity of cyanobacterial desert crusts Microenvironments and microscale productivity of cyanobacterial desert crusts

We used microsensors to characterize physicochemical microenvironments and photosynthesis occurring immediately after water saturation in two desert soil crusts from southeastern Utah, which were formed by the cyanobacteria Microcoleus vaginatus Gomont, Nostoc spp., and Scytonema sp. The light fields within the crusts presented steep vertical gradients in magnitude and spectral...
Authors
F. Garcia-Pichel, Jayne Belnap
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