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Publications

Filter Total Items: 1990

Population size and trends for nesting ospreys in northwestern Mexico: Region-wide surveys, 1977, 1992/1993 and 2006

We used a double-sampling technique (air plus ground survey) in 2006, with partial double coverage, to estimate the present size of the osprey (Pandion haliaetus) nesting population in northwestern Mexico. With the exception of Natividad, Cedros, and San Benito Islands along the Pacific Coast of Baja California, all three excluded from our coverage in 2006 due to fog, this survey was a repeat of p
Authors
Charles J. Henny, Daniel W. Anderson, Aradit Castellanos Vera, Jean-Luc E. Carton

Protocol for Landsat-Based Monitoring of Landscape Dynamics at North Coast and Cascades Network Parks

Background and Objectives As part of the National Park Service's larger goal of developing long-term monitoring programs in response to the Natural Resource Challenge of 2000, the parks of the North Coast and Cascades Network (NCCN) have determined that monitoring of landscape dynamics is necessary to track ecosystem health (Weber and others, 2005). Landscape dynamics refer to a broad suite of
Authors
Robert E. Kennedy, Warren B. Cohen, Alan A. Kirschbaum, Erik Haunreiter

Interim Summary: Nesting Counts of Ospreys and Brown Pelicans in Northwestern Mexico, 2006

The distribution and abundance of nesting populations of California brown pelicans (Pelecanus occidentalis californicus) and ospreys (Pandion haliaetus) were documented in 2006 in northwestern Mexico. For ospreys only, the 2006 data were compared to population estimates from two previous surveys (one conducted in 1977 and another conducted in the period 1992-1993). Overall, the total osprey nestin
Authors
Charles J. Henny, Daniel W. Anderson

Pygmy rabbit surveys on state lands in Oregon

The pygmy rabbit (Brachylagus idahoensis) is classified by the federal government as a species of concern (i.e., under review by the U.S. Fish and Wildlife Service for consideration as a candidate for listing as threatened or endangered under the Endangered Species Act) because of its specialized habitat requirements and evidence of declining populations. The Oregon Department of Fish and Wildlife
Authors
Joan Hagar, George Lienkaemper

Assessment and management of dead-wood habitat

The Bureau of Land Management (BLM) is in the process of revising its resource management plans for six districts in western and southern Oregon as the result of the settlement of a lawsuit brought by the American Forest Resource Council. A range of management alternatives is being considered and evaluated including at least one that will minimize reserves on O&C lands. In order to develop the bas
Authors
Joan Hagar

Longitudinal patterns of fish assemblages, aquatic habitat, and water temperature in the Lower Crooked River, Oregon

The Lower Crooked River is a remarkable groundwater-fed stream flowing through vertical basalt canyons in the Deschutes River Valley ecoregion in central Oregon (Pater and others, 1998). The 9-mile section of the river between the Crooked River National Grasslands boundary near Ogden Wayside and river mile (RM) 8 is protected under the National Wild and Scenic Rivers Act (16 U.S.C. 1271-1287) for
Authors
Christian E. Torgersen, David P. Hockman-Wert, Douglas S. Bateman, David W. Leer, Robert E. Gresswell

Fish movement ecology in high gradient headwater streams: Its relevance to fish passage restoration through stream culvert barriers

Restoration of fish passage through culvert barriers has emerged as a major issue in the Pacific Northwest and nationwide, in part, because of their potential influence on fish movement. Movement is an essential mechanism by which mobile animals acquire the resources necessary for the successful completion of their life-cycles. In this report, we provide a brief review of some essential characteri
Authors
Robert L. Hoffman, Jason B. Dunham

Rainforest birds: A land manager's guide to breeding bird habitat in young conifer forests in the Pacific Northwest

This document (hereafter Guide) has been prepared to assist land managers interested in conducting conservation and management activities to benefit breeding birds associated with young conifer forests in the Pacific Northwest. Audiences targeted for use of the Guide include land trusts, watershed councils, non-commercial private land owners, forest products companies, land-managing conservation o
Authors
Bob Altman, Joan Hagar

Body size affects the predatory interactions between introduced American Bullfrogs (Rana catesbeiana) and native anurans in China: An experimental study

Introduced American Bullfrogs (Rana catesbeiana) have established breeding populations in several provinces in China since their introduction in 1959. Although Bullfrogs are viewed as a potentially important predator of Chinese native anurans, their impacts in the field are difficult to quantify. We used two experiments to examine factors likely to mediate Bullfrog predation on native anurans. Fir
Authors
Y. Wang, Z. Guo, C.A. Pearl, Y. Li

Ecosystem N distribution and δ15N during a century of forest regrowth after agricultural abandonment

Stable isotope ratios of terrestrial ecosystem nitrogen (N) pools reflect internal processes and input–output balances. Disturbance generally increases N cycling and loss, yet few studies have examined ecosystem δ15N over a disturbance-recovery sequence. We used a chronosequence approach to examine N distribution and δ15N during forest regrowth after agricultural abandonment. Site ages ranged from
Authors
J.E. Compton, T.D. Hooker, S.S. Perakis

Conservation genetics of snowy plovers (Charadrius alexandrinus) in the Western Hemisphere: Population genetic structure and delineation of subspecies

We examined the genetic structure of snowy plovers (Charadrius alexandrinus) in North America, the Caribbean, and the west coast of South America to quantify variation within and among breeding areas and to test the validity of three previously recognized subspecies. Sequences (676 bp) from domains I and II of the mitochondrial control region were analyzed for 166 snowy plovers from 20 breeding ar
Authors
W.C. Funk, T.D. Mullins, S. M. Haig

Detection ratios on winter surveys of Rocky Mountain Trumpeter Swans Cygnus buccinator

We estimated the detection ratio for Rocky Mountain Trumpeter Swans Cygnus buccinator that were counted during aerial surveys made in winter. The standard survey involved counting white or grey birds on snow and ice and thus might be expected to have had low detection ratios. On the other hand, observers were permitted to circle areas where the birds were concentrated multiple times to obtain accu
Authors
J. Bart, C.D. Mitchell, M.N. Fisher, J.A. Dubovsky