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At least 163 records · Page 9Linked to original sources
USGS1974

The 1973 distribution and abundance of breeding ospreys in the Chesapeake Bay

An aerial survey in association with several intensive ground surveys yielded the first estimate of the size of the osprey ( Pandion haliaetus carolinensis ) nesting population in Chesapeake Bay. The 1973 population was estimated at 1,450 ± 30 pairs, of which 713 were on the western shore and 737 on the eastern shore. A small percentage of nonbreeders (possibly 2-5 percent) may be included in this estimate. Only 31.7 percent of the population was nesting in trees; the remaining birds utilized duck blinds (28.7 percent), channel markers (21.8 percent), and miscellaneous man-made structures (17.8 percent). The geographical distribution of nesting ospreys has quite likely changed during the last several decades as suitable artificial nesting sites have become more available. Furthermore, limited evidence suggests that birds nesting on the man-made sites were more successful than those nesting in trees. This study provides a basis for monitoring future changes in numbers and distribution.

Maryland, Virginia↗
USGS2016

Spatially explicit models of full-season productivity and implications for landscape management of Golden-winged Warblers in the western Great Lakes Region

The relationship between landscape structure and composition and full-season productivity (FSP) is poorly understood for most birds. For species of high conservation concern, insight into how productivity is related to landscape structure and composition can be used to develop more effective conservation strategies that increase recruitment. We monitored nest productivity and fledgling survival of Golden-winged Warblers ( Vermivora chrysoptera ), a species of high conservation concern, in managed forest landscapes at two sites in northern Minnesota, and one site in southeastern Manitoba, Canada from 2010 to 2012. We used logistic exposure models to identify the influence of landscape structure and composition on nest productivity and fledgling survival. We used the models to predict spatially explicit, FSP across our study sites to identify areas of low relative productivity that could be targeted for management. We then used our models of spatially explicit, FSP to simulate the impact of potential management actions on our study sites with the goal of increasing total population productivity. Unlike previous studies that suggested wetland cover types provide higher quality breeding habitat for Golden-winged Warblers, our models predicted 14% greater productivity in upland cover types. Simulated succession of a 9-ha grassland patch to a shrubby upland suitable for nesting increased the total number of fledglings produced by that patch and adjacent upland shrublands by 30%, despite decreasing individual productivity by 13%. Further simulated succession of the same patch described above into deciduous forest reduced the total number of fledglings produced to independence on a landscape by 18% because of a decrease in the area available for nesting. Simulated reduction in the cumulative length of shrubby edge within a 50-m radius of any location in our landscapes from 0.6 to 0.3 km increased FSP by 5%. Our models demonstrated that the effects of any single management action depended on the context of the surrounding landscape. We conclude that spatially explicit, FSP models that incorporate data from both the nesting and postfledging periods are useful for informing breeding habitat management plans for Golden-winged Warblers and that similar models can benefit management planning for many other species of conservation concern.

Studies in Avian Biology↗
USGS2009

Avian response to wildfire in interior Columbia basin shrubsteppe

Wildfire and conversion of sagebrush (Artemisia spp.) shrublands to cheatgrass (Bromus tectorum) grasslands is a serious threat to the shrubsteppe ecosystem, but few studies have documented wildfire's effects on birds with multiple years of pre- and post-fire data. Using data from avian point counts recorded 4 years before and 7 years after a large-scale, severe wildfire in the Columbia Basin of south-central Washington, we found significant effects of fire on population trends or mean abundance of nearly all species investigated. The Sage Sparrow (Amphispiza belli), a sagebrush obligate, was decreasing at a high rate both pre- and post-fire. Among species inhabiting more open shrubsteppe or grasslands, the mean abundance of three (Grasshopper Sparrow, Ammodramus savannarum; Western Meadowlark, Sturnella neglecta; Vesper Sparrow, Pooecetes gramineus) was lower post-fire and one (Lark Sparrow, Chondestes grammacus) showed an initial, but short-lived, increase post-fire before dropping below pre-fire levels. Only one (Horned Lark, Eremophila alpestris) increased steadily post-fire and had higher post-fire mean abundance. ?? 2009 by The Cooper Ornithological Society. All rights reserved.

Condor↗
USGS2026

Activity, but not size of Black-tailed Praire Dog colonies, is associated with higher Athene cunicularia hypugaea (Western Burrowing Owl) occupancy and reproductive success in the shortgrass prairie

Conservation in fragmented ecosystems, such as grasslands, has historically put more value on larger habitat patches but recent research suggests that small, high-quality habitat patches hold important conservation value. In many grassland systems, Athene cunicularia hypugaea (Western Burrowing Owl) relies on habitat patches created by Cynomys ludovicianus (Black-tailed Prairie Dog; hereafter prairie dog). Prairie dogs create important nesting habitat for A. c. hypugaea and other grassland birds. We examined the effect of size and characteristics of prairie dog colonies on A. c. hypugaea occupancy and reproductive success. We specifically looked at how colony size, prairie dog activity level, and vegetation characteristics influence these population parameters on 175 survey plots throughout eastern Colorado, U.S., across two sample years. Results are based on detections of adult and owlet A. c. hypugaea collected by paired observers traversing transects through study plots during the 2022 and 2023 A. c. hypugaea nesting seasons (May–August). Our top multistate occupancy model indicated that latitude affects A. c. hypugaea occupancy probabilities. Occupancy was higher in southern Colorado compared to northern Colorado. In addition, prairie dog activity was positively associated with A. c. hypugaea reproductive success. Colony size and vegetation characteristics were generally uninformative predictors of A. c. hypugaea occupancy and reproductive success. We compared our results to a previous A. c. hypugaea population assessment conducted within our study area in 2005 and found that active prairie dog colonies positively affected A. c. hypugaea local colonization while local extinction was driven by a transition of active prairie dog colonies to inactive. This study highlights the importance of high-quality prairie dog habitat patches for A. c. hypugaea nesting in fragmented grassland ecosystems, regardless of patch size.

Colorado↗
USGS2017

Shorebirds adjust spring arrival schedules with variable environmental conditions: Four decades of assessment on the Yukon–Kuskokwim Delta, Alaska

Arctic summers are brief, and there has been strong selection for migratory birds to arrive in Arctic nesting areas as early as possible to time breeding with peak food availability and complete reproduction. The timing of emergence of nesting habitat in spring is, however, extremely variable in the Arctic, and few long-term studies have examined the ability of avian migrants to track spring conditions to assure optimal nesting. Such studies require long-term migration monitoring under variable spring habitat conditions. These conditions were met during our long-term (1977–2008) study of the timing of arrival of shorebirds to their nesting grounds on the central Yukon–Kuskokwim (Y-K) Delta, in western Alaska. Over this period, the timing of arrival on the nesting grounds of 12 species of shorebirds varied significantly, with the Black-bellied Plover (Pluvialis squatarola) generally arriving first (mean arrival of 4 May), the Red Phalarope (Phalaropus fulicarius) usually arriving last (mean arrival of 20 May). The Western Sandpiper (Calidris mauri), Dunlin (Calidris alpina), and Red-necked Phalarope (Phalaropus lobatus), the most common breeding shorebird species we studied, all arrived about the same time each year (7–9 May). From year to year, first arrival of all species varied significantly by more than 2 weeks, but there was no long-term trend in arrival times over the length of our study. Shorebird arrival was highly correlated with the timing of the break-up of ice on the Kashunuk River, which in turn was correlated with decreasing snow cover and increasing ambient temperature. The date of break-up of river ice also varied by year but did not advance significantly during our study. After arriving on the breeding grounds, Arctic-nesting shorebirds rely on local food resources, which on the Y-K Delta they achieve by timing their arrival to coincide with availability of snow-free habitat. Temperatures along the terminal portions of the spring migration route were significantly correlated with both conditions on the breeding ground and the timing of shorebirds’ arrival there, which suggests that shorebirds may use environmental cues during spring migration to regulate its pace. Ours is one of the few multi-decadal studies to evaluate the responses of a suite of migrant species to annual variation in conditions in their Arctic breeding habitat. Shorebirds’ adaptations to variable conditions on the Y-K Delta are probably rooted in frequent changes to the landscape since the last glacial maximum. Such inherent flexibility may serve them well under future scenarios associated with a changing climate.

Alaska↗
USGS1985

Organophosphate insecticide (famphur) topically applied to cattle kills magpies and hawks

A systematic field study of a black-billed magpie ( Pica pica ) population revealed that magpies and red-tailed hawks ( Buteo jamaicensis ) were killed by famphur (=famophos, Warbex®) used as a pouron to control cattle warbles ( Hypoderma sp.). Magpie mortality began on treatment day and continued for more than 3 months (38 found dead); mortality peaked between Day 5 and Day 13. Estimates of magpie density (based on transects) decreased in both the control and treatment areas, but the decrease was greater in the treatment area. A red-tailed hawk found dead on Day 10 had eaten a famphur-contaminated magpie. Another red-tailed hawk was found alive but immobilized, and a third died outside the study area. Brain cholinesterase (ChE) activity was 70-92% depressed in all dead birds examined; famphur residues were detected in all 17 magpies and the 2 hawks analyzed. The amount of famphur obtained by the dead magpies was estimated at 5.2-6.1 mg/kg (based on residue concentrations in the gizzard), which was above the acute oral LD50 for several bird species. The cow hair portion (12%) of the pooled gizzard contents from 13 other dead magpies produced extremely high famphur residues (4,600 ppm). The residues persisted on cattle hair for more than 90 days post-treatment. Magpie populations in the far western states declined between 1968 and 1979, which corresponds with widespread use of famphur, although other factors may be involved.

Washington↗
USGS2007

Ecology and behavior of the Midget Faded Rattlesnake (Crotalus oreganus concolor) in Wyoming

We conducted a three-year study to describe the ecology and behavior of the Midget Faded Rattlesnake, Crotalus organus concolor. We encountered 426 and telemetered 50 C. o. concolor between 2000 and 2002. We found that their primary diet was lizards (associated with rock outcrops), though they will consume small mammals and birds. They den in aggregations, although in low numbers when compared to other subspecies. Movements and activity ranges were among the largest reported for rattlesnakes. Minimum convex polygon area was 117.8 ha for males, 63.9 ha for nongravid females, and 4.8 ha for gravid females. Mean distances traveled per year were 2122.0 m for males, 1956.0 m for nongravid females, and 296.7 m for gravid and postpartum females. Following emergence from hibernation, they spent several weeks shedding, often in aggregations before migration, and migrations occurred in early summer. Most snakes made straight-line movements to and from discrete summer activity ranges where short, multidirectional movements ensued, although others made multidirectional movements throughout the active season. We observed mating behavior between 21 July and 12 August. Gravid females gave birth during the third week of August. Mean clutch size was 4.17 (range 2-7). We found that the sex ratio was skewed favoring females 1:1.24, and they were sexually dimorphic in size (males SVL = 44.1 cm; females SVL = 40.8 cm). Our data further illustrate the diversity within the large group of Western Rattlesnakes (Crotalus viridis). Copyright 2007 Society for the Study of Amphibians and Reptiles.

Journal of Herpetology↗
USGS2009

Using simulation to improve wildlife surveys: Wintering mallards in Mississippi, USA

Wildlife conservation plans generally require reliable data about population abundance and density. Aerial surveys often can provide these data; however, associated costs necessitate designing and conducting surveys efficiently. We developed methods to simulate population distributions of mallards (Anas platyrhynchos) wintering in western Mississippi, USA, by combining bird observations from three previous strip-transect surveys and habitat data from three sets of satellite images representing conditions when surveys were conducted. For each simulated population distribution, we compared 12 primary survey designs and two secondary design options by using coefficients of variation (CV) of population indices as the primary criterion for assessing survey performance. In all, 3 of the 12 primary designs provided the best precision (CV???11.7%) and performed equally well (WR08082E1d.gif diff ???0.6%). Features of the designs that provided the largest gains in precision were optimal allocation of sample effort among strata and configuring the study area into five rather than four strata, to more precisely estimate mallard indices in areas of consistently high density. Of the two secondary design options, we found including a second observer to double the size of strip transects increased precision or decreased costs, whereas ratio estimation using auxiliary habitat data from satellite images did not increase precision appreciably. We recommend future surveys of mallard populations in our study area use the strata we developed, optimally allocate samples among strata, employ PPS or EPS sampling, and include two observers when qualified staff are available. More generally, the methods we developed to simulate population distributions from prior survey data provide a cost-effective method to assess performance of alternative wildlife surveys critical to informing management decisions, and could be extended to account for effects of detectability on estimates of true abundance. ?? 2009 CSIRO.

Wildlife Research↗
USGS2014

Pacific Continental Shelf Environmental Assessment (PaCSEA): aerial seabird and marine mammal surveys off northern California, Oregon, and Washington, 2011-2012

Marine birds and mammals comprise an important community of meso- and upper-trophic-level predators within the northern California Current System (NCCS). The NCCS is located within one of the world’s four major eastern boundary currents and is characterized by an abundant and diverse marine ecosystem fuelled seasonally by wind-driven upwelling which supplies nutrient-rich water to abundant phytoplankton inhabiting the surface euphotic zone. The oceanographic conditions throughout the NCCS fluctuate according to well-described seasonal, inter-annual, and decadal cycles. Such oceanographic variability can influence patterns in the distribution, abundance, and habitat use among marine birds and mammals. Although there are an increasing number of studies documenting distributions and abundances among birds and mammals in various portions of the NCCS, there have been no comprehensive, large-scale, multi-seasonal surveys completed throughout this region since the early 1980s (off northern California; Briggs et al. 1987) and early 1990s (off Oregon and Washington; Bonnell et al. 1992, Briggs et al. 1992, Green et al. 1992). During 2011 and 2012, we completed the Pacific Continental Shelf Environmental Assessment (PaCSEA) which included replicated surveys over the continental shelfslope from shore to the 2000-meter (m) isobath along 32 broad-scale transects from Fort Bragg, California (39° N) through Grays Harbor, Washington (47° N). Additionally, surveys at a finer scale were conducted over the continental shelf within six designated Focal Areas: Fort Bragg, CA; Eureka, CA; Siltcoos Bank, OR; Newport, OR; Nehalem Bank, OR; and Grays Harbor, WA. We completed a total of 26,752 km of standardized, low-elevation aerial survey effort across three bathymetric domains: inner-shelf waters (<100-m depth), outer shelf waters (100 – 200-m depth) and continental slope waters (200 – 2000-m depth). Survey effort was similar among seasons (winter, summer, and fall) and between years and varied according to the three bathymetric domains: 47% (12,646 km) covered the continental slope, 33% (8887 km) covered the inner-shelf (0 – 100-m depth), and 20% (5,219 km) covered the outer-shelf. Overall, we recorded 15,403 sightings of 59,466 individual marine birds (12 families, 54 species). During winter, seven species groupings comprised >90% of the total number of birds counted (19,033) with Common Murres (Uria aalge) representing the majority of individuals counted (70.4% of total). The remaining six most abundant taxa included: Surf/White-winged Scoters (Melanitta perspicillata/M. fusca; 4.8% of total), Herring/Thayer’s Gulls (Larus argentatus/L. thayeri; 3.8% of total), Cassin’s Auklets (Ptychoramphus aleuticus; 3.8% of total), Glaucous-winged Gulls (Larus glaucescens; 3.7% of total), Black-legged Kittiwakes (Rissa tridactyla; 2.0% of total), and Western Gulls (Larus occidentalis; 1.9% of total). During summer, five species comprised >95% of the total number of birds counted (17,063) with the majority comprised of Common Murres (54.1% of total) and Sooty Shearwaters (Puffinus griseus; 34.4% of total). The remaining most abundant three taxa included: Fork-tailed Storm-Petrels (Oceanodroma furcata; 3.3% of total), Western Gulls (2.1% of total), and Leach’s Storm-Petrels (Oceanodroma leucorhoa; 1.1% of total). During fall, nine species comprised >85% of the total number of birds counted (23,376) with the majority comprised of Common Murres (50.0% of total) and Sooty Shearwaters (10.5% of total). The remaining seven taxa included Cassin’s Auklets (5.2% of total), Surf/White-winged Scoters (5.1% of total), Fork-tailed Storm-Petrels (3.8% of total), Red/Red-necked Phalaropes (Phalaropus fulicarius/P. lobatus; 3.2% of total), California Gulls (Larus californicus; 3.1% of total), Northern Fulmars (Fulmarus glacialis; 2.7% of total), and Sabine’s Gulls (Xema sabini; 2.2% of total). Throughout the entire PaCSEA survey area, average densities (± SE) at sea for all marine birds combined were similar between fall (23.7 ± 1.9 birds km -2 ) and winter (24.0 ± 1.9 birds km -2 ) and least during summer (16.3 ± 2.2 birds km -2 ). Marine bird densities at sea varied according to bathymetric domain and season. Throughout the entire PaCSEA study area average densities (± SE) for all marine birds combined were greatest over the inner-shelf domain (<100-m depth) during fall (49.4 ± 5.0 birds km -2 ) and similar during winter (37.4 ± 4.6 birds km -2 ) and summer (37.5 ± 6.4 birds km -2 ). Within the outer-shelf domain (100 – 200-m depth), average densities for all marine birds combined were greatest during winter (34.6 ± 4.2 birds km-2), lesser during fall (16.2 ± 1.7 birds km-2), and least during summer (6.9 ± 1.1 birds km-2). Within the farthest offshore waters over the continental slope domain (200 – 2000-m depth) average densities for all marine birds combined were greatest during fall (10.0 ± 2.2 birds km -2 ) and winter (9.3 ± 1.5 birds km -2 ), and lesser during summer (6.2 ± 1.4 birds km -2 ). We observed 16 cetacean species and five pinniped species. Among the Mysticeti (baleen whales), humpback whales (Megaptera novaeangliae) were most frequently observed (114 sightings of 264 individuals) during summer and fall mostly over the outer-shelf and slope waters, however, individuals were also seen within the Siltcoos, Nehalem, Fort Bragg, and Eureka Focal Areas. We recorded 11 Odontoceti (toothed whale) species. Harbor porpoises (Phocoena phocoena) were the most frequently sighted (164 sightings of 270 individuals). Harbor porpoises were present year-round and most frequently sighted within the inner-shelf domain throughout the entire study area in all seasons. Harbor porpoises occurred in all six Focal Areas, with noteworthy aggregations within the Eureka, Siltcoos, and Grays Harbor Focal Areas. We recorded 246 sightings of 375 individual pinnipeds (5 species). California sea lions (Zalophus californianus) were the most frequently sighted and were present year-round with slightly more sightings recorded during the fall. California sea lions showed a decreasing frequency of sightings and relative abundance with distance from shore across the bathymetric domains surveyed, being most frequently observed over the inner-shelf. Northern elephant seals (Mirounga angustirostris), harbor seals (Phoca vitulina), and northern fur seals (Callorhinus ursinus) were observed occasionally during all seasons with harbor seals occurring nearshore (usually within 10 km of the coast) and northern fur seals almost exclusively beyond the shelf break (> 200-m depth), especially during winter off Oregon and Washington. Northern (Steller’s) sea lions (Eumetopias jubatus) were uncommonly sighted during winter and fall.

California;Oregon;Washington↗
USGS2018

Phase 1 studies summary of major findings of the South Bay Salt Pond Restoration Project, South San Francisco Bay, California

Executive Summary The South Bay Salt Pond Restoration Project (Project) is one of the largest restoration efforts in the United States. It is located in South San Francisco Bay of California. It is unique not only for its size—more than 15,000 acres—but also for its location adjacent to one of the nation’s largest urban areas, home to more than 4 million people (Alameda, Santa Clara, and San Mateo Counties). The Project is intended to restore and enhance wetlands in South San Francisco Bay while providing for flood management, wildlife-oriented public access, and recreation. Restoration goals of the project are to provide a mosaic of saltmarsh habitat to benefit marsh species and managed ponds to benefit waterbirds, throughout 3 complexes and 54 former salt ponds. Although much is known about the project area, significant uncertainties remain with a project of this geographic and temporal scale of an estimated 50 years to complete the restoration. For example, in order to convert anywhere from 50 to 90 percent of the existing managed ponds to saltmarsh habitat, conservation managers first enhance the habitat of managed ponds in order to increase use by waterbirds, and provide migratory, wintering, and nesting habitat for more than 90 species of waterbirds. Project managers have concluded that the best way to address these uncertainties is to carefully implement the project in phases and learn from the outcome of each phase. The Adaptive Management Plan (AMP) identifies specific restoration targets for multiple aspects of the Project and defines triggers that would necessitate some type of management action if a particular aspect is trending negatively. U.S. Geological Survey (USGS) biologist Laura Valoppi served as the project Lead Scientist and oversaw implementation of the AMP in coordination with other members of the Project Management Team (PMT), comprised of representatives from the California State Coastal Conservancy, California Department of Fish and Wildlife, the Santa Clara Valley Water District, the U.S. Army Corps of Engineers, and the U.S. Fish and Wildlife Service. To implement the AMP, the PMT have selected and funded applied studies and monitoring projects to address key uncertainties. This information is used by the PMT to make decisions about current management of the project area and future restoration actions in order to meet project. This document summarizes the major scientific findings from studies conducted from 2009 to 2016, as part of the science program that was conducted in conjunction with Phase 1 restoration and management actions. Additionally, this report summarizes the management response to the study results under the guidance of the AMP framework and provides a list of suggested studies to be conducted in “Phase 2–A scorecard summarizing the Project’s progress toward meeting the AMP goals for a range of Project objectives.” The scoring to date indicates that the Project is meeting or exceeding expectations for sediment accretion and western snowy plover ( Charadrius alexandrinus nivosus ) recovery. There is uncertainty with respect to objectives for California gulls ( Larus californicus ), California least tern ( Sternula antillarum ), steelhead trout ( Oncorhynchus mykiss ), and regulatory water quality objectives. Water quality and algal blooms, specifically of the managed ponds, is indicated as trending negative. However, the vast majority of objectives are trending positive, including increased abundance for a number of bird guilds, increasing marsh habitat, maintenance of mudflats, visitor experience, estuarine fish numbers, and special-status marsh species numbers.

California↗
USGS2019

Spatial variation in aquatic invertebrate and riparian songbird mercury exposure across a river-reservoir system with a legacy of mercury contamination

Mercury (Hg) loading and methylation in aquatic systems causes a variety of deleterious effects for fish and wildlife populations. Relatively little research has focused on Hg movement into riparian food webs and how this is modulated by habitat characteristics. This study characterized differences in Hg exposure in aquatic invertebrates and riparian songbirds across a large portion of the Willamette River system in western Oregon, starting at a Hg-contaminated Superfund site in the headwaters (Black Butte Hg Mine) and including a reservoir known to methylate Hg (Cottage Grove Reservoir), all downstream reaches (Coast Fork and Willamette River) and off-channel wetland complexes (Willamette Valley National Wildlife Refuge Complex). After accounting for year, date, and site differences in a mixed effects model, MeHg concentrations in aquatic invertebrates varied spatially among habitat categories and invertebrate orders. Similarly, THg in songbird blood varied by among habitat categories and bird species. The highest Hg concentrations occurred near the Hg mine, but Hg did not decline linearly with distance from the source of contamination. Birds were consistently elevated in Hg in habitats commonly associated with enhanced MeHg production, such as backwater or wetlands. We found a positive but weak correlation between aquatic invertebrate MeHg concentrations and songbird THg concentrations on a site-specific basis. Our findings suggest that Hg risk to riparian songbirds can extend beyond point-source contaminated areas, highlighting the importance of assessing exposure in surrounding habitats where methylmercury production may be elevated, such as reservoirs and wetlands.

Oregon↗
USGS2001

Inability to predict geographic origin of Yellow-headed Blackbirds, Xanthocephalus xanthocephalus, during migration

Yellow-headed Blackbirds (Xanthocephalus xanthocephalus) collected at different breeding locations in Alberta, Saskatchewan, Manitoba, and North Dakota exhibit clearly discernable morphometric differences with larger bodied birds found at more northern and western locations. We reduced eight skeletal measurements and body length from adult female and male Yellow-headed Blackbirds to their first two principal components. Principal component scores progressively increased at more northwestern locations. Principal component scores were also derived from measurements of birds collected in central North Dakota throughout summer and fall. We hypothesized an increase in principal component scores of Yellow-headed Blackbirds from summer through fall within central North Dakota as larger bodied migrants arrived and displaced local breeding birds. However, we were unable to detect an increase in principal component scores from mid-June though mid-September over two years of study. Discriminant models that were developed to distinguish birds breeding in Canada from those breeding in the USA were poor predictors of the migratory status of Yellow-headed Blackbirds. Thus, we were unable to exploit the morphometric differences inherent among Yellow-headed Blackbirds breeding at different geographic locations to quantify the timing or the magnitude of their migration through central North Dakota.

Canadian Field-Naturalist↗
USGS1984

Effects of heptachlor- and lindane-treated seed on Canada geese

A study of Canada geese (B. canadensis) was conducted in the Pacific Northwest from 1978 through 1981. Lowered reproductive success, mortality of adults, and a population decline of resident western Canada geese (B. c. moffitti) at the Umatilla National Wildlife Refuge (Umatilla NWR) Oregon and Washington [USA] were associated with the use of heptachlor-treated wheat. Analyses of eggs and tissues from dead geese provided strong evidence that heptachlor was responsible for the mortality and decreased production. Residues of heptachlor epoxide (HE) in brains of B. c. moffitti found dead in 1978 and 1979 equalled or exceeded the lethal hazard zone of 8-9 .mu.g/g in experimental passerine birds; HE residues of > 10 .mu.g/g in sample eggs were associated with low nest success. The breeding population of Canada geese at Umatilla decreased from 129 pairs in 1974 to about 100 pairs in 1979. The heptachlor problem was restricted to the Umatilla area; HE residues were low in tissues and eggs collected at other sites in Oregon, Washington and Idaho. In Sept., 1979, the use of heptachlor-treated seed was banned in a 1700-km2 area that encompassed both sides of the Columbia River near Umatilla. Lindane was substituted for heptachlor in the restricted area in 1979, and its use was extended to much of the Columbia Basin in 1981. Concurrently, reproductive success of geese increased, mortality decreased, and the nesting population increased to 170 pairs by 1983. There was no evidence for either biomagnification of lindance residues from treated seed to goose tissues or eggs or for induction of adverse effects by this compound.

Oregon, Washington↗
USGS2018

Prevalence and risk factors of Trichomonas gallinae and trichomonosis in golden eagle (Aquila chrysaetos) nestlings in western North America

Avian trichomonosis, caused by the protozoan Trichomonas gallinae , affects bird-eating raptors worldwide. Raptors can develop trichomonosis by feeding on infected prey, particularly Rock Pigeons (C olumba livia ), which are a reservoir for T. gallinae . Raptors may be particularly vulnerable to T. gallinae infection in degraded habitats, where changes in resources may cause raptors to switch from foraging on native prey to synanthropic avian species such as Rock Pigeons. Golden Eagles ( Aquila chrysaetos ) typically forage on mammals; however, habitat across much of their range is experiencing degradation through changes in land use, climate, and human encroachment. In 2015, we examined the prevalence of T. gallinae infection in Golden Eagle nestlings across western North America and conducted an intensive study on factors associated with T. gallinae infection and trichomonosis in southwestern Idaho. We found T. gallinae infection in 13% (12/96) of eagle nestlings across 10 western states and in 41% (13/32) of nestlings in southwestern Idaho. At the Idaho site, the probability of T. gallinae infection increased as the proportion of Rock Pigeons in nestling diet increased. Nestlings with diets that consisted of ≥10% Rock Pigeons had a very high probability of T. gallinae infection. We compared historical (1971–81) and recent (2014–15) diet data and incidence of trichomonosis lesions of nestling eagles in Idaho and found that the proportion of Rock Pigeons in eagle diets was higher in recent versus historical periods, as was the proportion of eagle nestlings with trichomonosis lesions. Our results suggested that localized shifts in eagle diet that result from habitat degradation and loss of historical prey resources have the potential to affect Golden Eagle nestling survival and supported the hypothesis that land use change can alter biologic communities in a way that might have consequences for disease infection and host susceptibility.

Journal of Wildlife Diseases↗
USGS2016

Oak mistletoe ( Phoradendron villosum ) is linked to microhabitat availability and avian diversity in Oregon white oak ( Quercus garryana ) woodlands

Mistletoes are parasitic or hemi-parasitic flowering plants that parasitize woody plants around the globe. Important food and cover resources provided by mistletoes have been related to strong patterns of positive association between wildlife diversity and mistletoe density. Mistletoes also create microhabitat features known to be important to wildlife by causing deformations in their host trees. However, links between availability of mistletoe-formed microhabitat and wildlife diversity has not been well studied. We investigated this relationship by quantifying microhabitat features and avian abundance and diversity related to infection by Oak Mistletoe (Phoradendron villosum) in Oregon White Oak (Quercus garryana). Q. garryana woodlands support several avian species of conservation concern, so an understanding of the influence of mistletoe on wildlife habitat is critical. Our results suggest that 1) structural heterogeneity within tree crowns; 2) avian species richness and abundance are positively associated with mistletoe load; and 3) P. villosum fruit, available is an important food for western bluebird (Sialia mexicana) and other wildlife in late autumn and early winter. If a goal of restoration is to maintain habitat for oak-associated bird species, managers should consider the retention of some oaks hosting mistletoe.

Oregon↗
USGS2004

The distribution of seabirds and pinnipeds in Marguerite Bay and their relationship to physical features during austral winter 2001

The distribution of seabirds and pinnipeds and their relationship to physical oceanographic variables were investigated as part of the US Southern Ocean Global Ocean Ecosystem Dynamics field program along a study grid centered around Marguerite Bay on the west Antarctic Peninsula during late fall (April-May) and winter (July-August), 2001. Sea-ice conditions during the cruises provided an opportunity to compare the relationship among physical oceanographic variables and species distributions before and after the development of pack ice. During the fall cruise before pack ice development, both sea-ice-affiliated species and open-water-affiliated were observed in the area. The most common ice-affiliated species observed at this time were snow petrel (Pagodroma nivea, 0.7 individuals km-2) and Antarctic petrel (Thalassoica antarctica, 0.2 individuals km-2) and the most common open-water-affiliated species were blue petrel (Halobaena caerulea, 0.4 individuals km-2), cape petrel (Daption capense, 0.2 individuals km-2), and southern fulmar (Fulmarus glacialoides, 0.1 individuals km-2). In addition, Antarctic fur seals (Arctocephalus gazella, 0.1 individuals km-2) and crabeater seals (Lobodon carcinophagus, 0.4 individuals km-2) were observed in low numbers. Akaike's information criterion was used to assess competing models that predicted predator distributions based on physical oceanographic variables proposed to structure predator distribution in previous research. These analyses indicated that predator distributions were primarily associated with water-mass structure and variability in bottom depth during the fall cruise. Crabeater seal, snow petrel, Antarctic petrel, and southern fulmar had higher densities in Inner Shelf Water, particularly near Alexander Island where a coastal current was present. Blue petrel, kelp gull (Larus dominicanus), and southern giant petrel (Macronectes giganteus) were positively associated with variability in bottom depth in April-May, suggesting that hydrographic processes influenced by bathymetry may have been important in structuring bird distributions. After the development of pack ice, during July and August, only sea-ice-affiliated species, including snow petrel (1.0 individuals km-2), Antarctic petrel (0.1 individuals km-2), Ade??lie penguin (Pygoscelis adeliae, 0.4 individuals km-2), and crabeater seal (0.3 individuals km-2), were observed. Seabirds were primarily associated with sea-ice characteristics (e.g. sea-ice concentration, sea-ice type) rather than the water-column environment later in the winter. Results from this study suggest that the timing and extent of sea-ice development in the fall may influence over-winter predation by seabirds and pinnipeds on zooplankton and fish on the western Antarctic Peninsula. Delays in sea-ice development may allow seabirds and pinnipeds access to biologically important areas such as the Inner Shelf Water for a longer period of time thereby increasing predation on zooplankton and fish. ?? 2004 Elsevier Ltd. All rights reserved.

Deep-Sea Research Part II: Topical Studies in Ocea↗
USGS1997

Distribution of autumn-staging Lesser Snow Geese on the northeast coastal plain of Alaska

We conducted aerial surveys of Lesser Snow Geese ( Chen caerulescens caerulescens ) during autumn staging on the coastal plain of the Arctic National Wildlife Refuge (ANWR) in northeast Alaska from late August through September, 1982 - 1993. We evaluated numbers and distribution of Snow Geese that staged on the ANWR, compared abundance of birds among 5 x 5-km cells used frequently (5 - 8 yr), periodically (3 - 4 yr), or infrequently (1 - 2 yr), and examined distribution changes within years. Maximum numbers of Snow Geese observed annually were highly variable (range 12,828 - 309,225). Snow Goose flocks occurred across 605,000 ha of the coastal plain, but used some areas more frequently than others. Frequently used cells (38 of 363 cells in the study area) were non-randomly distributed and primarily occurred on the central coastal plain between the wet coastal and steep foothills regions. Abundance of geese was greatest in frequently used, intermediate in periodically used, and lowest in infrequently used cells. Within years, Snow Goose numbers and flock locations varied between surveys, possibly because geese moved to different foraging areas during staging. The widespread distribution and annual variability in numbers of Snow Geese on the coastal plain was likely because birds used foraging habitats that were spatially and temporally heterogeneous. The ANWR coastal plain is an important component of the fall-staging area used by Snow Geese that nest in the western Canadian Arctic. Management decisions that affect the region should reflect its value to migrating Snow Geese.

Alaska↗
USGS1988

Colony attendance and population monitoring of Black-legged Kittiwakes on the Semidi Islands, Alaska

Patterns of colony attendance in Black-legged Kittiwakes ( Rissa tridactyla ) were studied over 5 years on the Semidi Islands, western Gulf of Alaska. A census period of 50 days, extending from first egg laying through final hatching, was appropriate because counts made then were subject to the least amount of daily variation. Five counts during that period were sufficient to detect a 25% change in numbers between years; counts made on all 50 days of the census period would detect a 5 to 7% change. There was little evidence for seasonal trends or serial correlation of counts during the census period, but attendance was negatively correlated with wind speed. Half of an apparent 17% increase in population between 1980 and 1981 was due to birds spending more time at their nest sites in the latter year, thereby increasing the mean of attendance counts. Despite such difficulties in the interpretation of attendance counts, birds were considered to be better counting units for population monitoring than nests, because nest densities were subject to large annual fluctuations in breeding effort.

Alaska↗