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At least 721 records · Page 40Linked to original sources
USGS2021

Synthesis of nest predation impacts of common ravens on sensitive avian species

Decades of mounting scientific evidence have revealed that common raven ( Corvus corax ; raven) population numbers have been increasing across nearly all regions of their geographic range in North America. Concomitantly, numerous native wildlife species have experienced elevated predation rates from ravens as populations have increased and expanded their range. Managers are concerned that increased raven predation of many threatened and endangered avian species in the U.S. and Canada during nesting periods may be hampering species recovery. We explored the literature to aggregate existing knowledge and evaluate the impacts of raven predation on nests and young of sensitive avian species. We used this information to develop a simple relative index for each species, the “Raven Impact Index” (RII). The RII incorporated the species demographic rates, abundance of ravens in relation to each sensitive species’ breeding range, and the degree of overlap between raven and sensitive prey distributions. We also developed a second relative descriptor describing our confidence in each RII, termed a “Impact Credibility Index (ICI).” The species ICI was based on the number of published studies and the type of evidence presented (e.g., circumstantial vs. direct). We found evidence of nest predation on 8 sensitive avian species and suspected nest predation on 1 additional species. All species shared aspects of nesting biology that suggested they would likely be susceptible to raven nest predation. The RII varied among prey species, with greater sage-grouse ( Centrocercus urophasianus ) having the highest relative impact values, followed by snowy plover ( Charadrius nivosus nivosus ), marbled murrelet ( Brachyramphus marmoratus ), and Gunnison sage-grouse ( Centrocercus minimus ). Our species RII is intended to inform management decisions regarding actions that mitigate the negative effects of raven predation of sensitive avian species. Although elevated nest predation may be of high conservation concern, it is important to recognize that all of the sensitive native prey species we established an RII for also face multiple conservation threats.

Human–Wildlife Interactions↗
USGS2024

Ecological and social drivers of Mexican wolf home range size across spatiotemporal scales

Elucidating factors influencing home range size is fundamental to the ecology and management of wildlife species, particularly those of conservation concern, because they can provide insight into how species utilize and interact with their environment. Variation in home range size can be related to intraspecific competition and social organization, energetic requirements in relation to habitat productivity, allometric relationships, and population density. The Mexican Gray Wolf ( Canis lupus baileyi ) is an endangered subspecies of the Gray Wolf whose home range size has not yet been studied. We examined ecological and social drivers of home range size of 22 Mexican Wolf packs between 2017 and 2021 across 4 biological time frames: annual; denning; post-denning; and non-denning. We used a 95% Brownian Bridge Movement Model home range estimator and generalized linear mixed-effect models to assess these relationships. Home range size was inversely correlated with estimated ungulate biomass, which was the most influential driver of home range size at annual and post-denning time frames. Larger packs utilized larger ranges during denning and post-denning time frames, while packs with larger litters had smaller ranges during the denning season. Snow depth was inversely related to home range size during the non-denning season. Our results indicate that both ecological and social factors are important and seasonally dependent in driving Mexican Wolf home range size. Use of a multiscale approach in future home range studies could discern relevant factors for species during time frames of interest.

Journal of Mammology↗
USGS1995

Kodiak brown bears

Brown bears ( Ursus arctos middendorffi ) on the Kodiak Archipelago are famous for their large size and seasonal concentrations at salmon streams. Sport hunting of Kodiak bears has been popular since World War II. Their value as captivating subjects to observe or photograph is a more recent development that is increasing rapidly; visitors from around the world come to experience brown bears on Kodiak, adding substantially to Alaska's economy. An equally important contribution of brown bears is their value as an indicator of ecosystem vitality. Despite high population numbers, Kodiak bears are vulnerable to the environmental effects that have seriously depleted brown bear populations in Europe and parts of North America (Cowan 1972; Servheen 1990). They are long-lived mammals that require large expanses of land to meet biological needs, and their low reproductive rate limits population recovery. Energy development, depletion of salmon resources, and recreational growth are factors that can adversely affect bears and, in doing so, signal a loss of environmental quality affecting many species. Management of Kodiak brown bears is directed at maintaining current density, distribution, and habitat-use patterns. This goal is challenged by growing levels of commercial and private use throughout the region. An immediate concern is cabin and lodge development on 121,500 ha (300,000 acres), formerly part of the Kodiak National Wildlife Refuge, that were deeded to Alaska Natives via the Alaska Native Claims Settlement Act. Much of that Native-conveyed land is coastal or riparian habitat especially important to brown bears during summer and fall. Concurrently, recreational use of the Kodiak refuge is increasing about 10% annually (USFWS 1987). Sport fishing, bear photography, and deer and elk hunting often put bears and humans in direct conflict (Smith et al. 1989). Timber harvest on Afognak Island, uncertain trends of salmon populations due to natural or human-caused events (e.g., Exxon Valdez oil spill), and hydroelectric development (Smith and Van Daele 1990) could impose additional long-term effects on localized bear populations.

Alaska↗
USGS2020

The changing sociocultural context of wildlife conservation

We introduced a multilevel model of value shift to describe the changing social context of wildlife conservation. Our model depicts how cultural-level processes driven by modernization (e.g., increased wealth, education, and urbanization) affect changes in individual-level cognition that prompt a shift from domination to mutualism wildlife values. Domination values promote beliefs that wildlife should be used primarily to benefit humans, whereas mutualism values adopt a view that wildlife are part of one's social network and worthy of care and compassion. Such shifts create emergent effects (e.g., new interest groups) and challenges to wildlife management organizations (e.g., increased conflict) and dramatically alter the sociopolitical context of conservation decisions. Although this model is likely applicable to many modernized countries, we tested it with data from a 2017–2018 nationwide survey (mail and email panel) of 43,949 residents in the United States. We conducted hierarchical linear modeling and correlational analysis to examine relationships. Modernization variables had strong state-level effects on domination and mutualism. Higher levels of education, income, and urbanization were associated with higher percentages of mutualists and lower percentages of traditionalists, who have strong domination values. Values affected attitudes toward wildlife management challenges; for example, states with higher proportions of mutualists were less supportive of lethal control of wolves ( Canis lupus ) and had lower percentages of active hunters, who represent the traditional clientele of state wildlife agencies in the United States. We contend that agencies will need to embrace new strategies to engage and represent a growing segment of the public with mutualism values. Our model merits testing for application in other countries.

Conservation Biology↗
USGS1993

Techniques for research into woodcocks: experiences and recommendations

We describe methods for the study of the American woodcock (Scolopax minor) at the Moosehorn National Wildlife Refuge. Described are techniques for the capture of particular age-sex cohorts during different times of the year, the aging and sexing, the evaluation of habitat components, and the estimation of population size. We describe successful and tried but rejected techniques with radio-telemetry for the study of survival and habitat use.

Biological Report↗
USGS1991

Chufa biology and management

Chufa (Cyperus esculentus) is an emergent perennial sedge that is common in seasonally flooded wetlands. Although chufa is common in many States, it is most abundant in the Southeast, including the Mississippi alluvial valley (Fig. 1). Belowground biomass of chufa, especially the tubers, serves as a valuable food source for waterfowl and cranes. Chufa tubers rank tenth among the most important waterfowl foods in the United States.

Fish and Wildlife Leaflet↗
USGS2015

River corridor science: Hydrologic exchange and ecological consequences from bedforms to basins

Previously regarded as the passive drains of watersheds, over the past 50 years, rivers have progressively been recognized as being actively connected with off-channel environments. These connections prolong physical storage and enhance reactive processing to alter water chemistry and downstream transport of materials and energy. Here we propose river corridor science as a concept that integrates downstream transport with lateral and vertical exchange across interfaces. Thus, the river corridor, rather than the wetted river channel itself, is an increasingly common unit of study. Main channel exchange with recirculating marginal waters, hyporheic exchange, bank storage, and overbank flow onto floodplains are all included under a broad continuum of interactions known as “hydrologic exchange flows.” Hydrologists, geomorphologists, geochemists, and aquatic and terrestrial ecologists are cooperating in studies that reveal the dynamic interactions among hydrologic exchange flows and consequences for water quality improvement, modulation of river metabolism, habitat provision for vegetation, fish, and wildlife, and other valued ecosystem services. The need for better integration of science and management is keenly felt, from testing effectiveness of stream restoration and riparian buffers all the way to reevaluating the definition of the waters of the United States to clarify the regulatory authority under the Clean Water Act. A major challenge for scientists is linking the small-scale physical drivers with their larger-scale fluvial and geomorphic context and ecological consequences. Although the fine scales of field and laboratory studies are best suited to identifying the fundamental physical and biological processes, that understanding must be successfully linked to cumulative effects at watershed to regional and continental scales.

Water Resources Research↗
USGS1996

South Florida wetlands ecosystem; biogeochemical processes in peat

The South Florida wetlands ecosystem is an environment of great size and ecological diversity (figs. 1 and 2). The landscape diversity and subtropical setting of this ecosystem provide a habitat for an abundance of plants and wildlife, some of which are unique to South Florida. South Florida wetlands are currently in crisis, however, due to the combined effects of agriculture, urbanization, and nearly 100 years of water management. Serious problems facing this ecosystem include (1) phosphorus contamination producing nutrient enrichment, which is causing changes in the native vegetation, (2) methylmercury contamination of fish and other wildlife, which poses a potential threat to human health, (3) changes in the natural flow of water in the region, resulting in more frequent drying of wetlands, loss of organic soils, and a reduction in freshwater flow to Florida Bay, (4) hypersalinity, massive algal blooms, and seagrass loss in parts of Florida Bay, and (5) a decrease in wildlife populations, especially those of wading birds. This U.S. Geological Survey (USGS) project focuses on the role of organic-rich sediments (peat) of South Florida wetlands in regulating the concentrations and impact of important chemical species in the environment. The cycling of carbon, nitrogen, phosphorus, and sulfur in peat is an important factor in the regulation of water quality in the South Florida wetlands ecosystem. These elements are central to many of the contamination issues facing South Florida wetlands, such as nutrient enrichment, mercury toxicity, and loss of peat. Many important chemical and biological reactions occur in peat and control the fate of chemical species in wetlands. Wetland scientists often refer to these reactions as biogeochemical processes, because they are chemical reactions usually mediated by microorganisms in a geological environment. An understanding of the biogeochemical processes in peat of South Florida wetlands will provide a basis for evaluating the effects on water quality of (1) constructing buffer wetlands to alleviate nutrient contamination and (2) replumbing the ecosystem to restore natural water flow. The results may also suggest new approaches for solving problems of contamination and water quality in these wetlands. A second focus of this project will be on the geochemical history of the South Florida ecosystem. Peat is a repository of the history of past environmental conditions in the wetland. Before effective action can be taken to correct many of the problems facing these wetlands, we must first study the biogeochemistry of the peat at depth in order to understand whether current problems are the result of recent human activity or are part of a long-term natural cycle. Coordination with other (USGS) projects for South Florida is ongoing. These projects are studying the biological history of the ecosystem by using pollen and shells buried in the peat, together with procedures for dating the peat at various depths, to develop an overall ecosystem history model, with emphasis on the last 100 years.

Fact Sheet↗
USGS2011

Breccia-pipe uranium mining in northern Arizona: Estimate of resources and assessment of historical effects

About 1 million acres of Federal land in the Grand Canyon region of Arizona were temporarily withdrawn from new mining claims in July 2009 by the Secretary of the Interior because of concern that increased uranium mining could have negative impacts on the land, water, people, and wildlife. During a 2-year interval, a Federal team led by the Bureau of Land Management is evaluating the effects of withdrawing these lands for extended periods. As part of this team, the U.S. Geological Survey (USGS) conducted a series of short-term studies to examine the historical effects of breccia-pipe uranium mining in the region. The USGS studies provide estimates of uranium resources affected by the possible land withdrawal, examine the effects of previous breccia-pipe mining, summarize water-chemistry data for streams and springs, and investigate potential biological pathways of exposure to uranium and associated contaminants. This fact sheet summarizes results through December 2009 and outlines further research needs.

Arizona↗
USGS2005

Captive breeding and reintroduction of the endangered masked bobwhite

Efforts to restore the endangered masked bobwhite ( Colinus virginianus ridgwayi ) to its former range have required 1) habitat acquisition, restoration, and preservation; 2) captive propagation; and 3) reintroduction of captive-bred stock. In its role to recover the masked bobwhite, the Patuxent Wildlife Research Center (U.S. Fish and Wildlife Service) has refined captive breeding techniques; provided captive-produced stock for release; conducted field research on the distribution, limiting factors, and habitat characteristics of this species; and developed release methods. Techniques for the husbandry and captive management, breeding, artificial incubation and hatching of eggs, and rearing of young of the masked bobwhite have been developed. Successful reintroduction techniques for the masked bobwhite have included prerelease conditioning and/or cross-fostering of captive-reared masked bobwhite chicks to a wild-caught, related, vasectomized bobwhite species and their release to the wild as family units. In addition, the establishment by the U.S. Fish and Wildlife Service of the Buenos Aires National Wildlife Refuge in 1985 has further enhanced the potential for establishing a self-sustaining population of the masked bobwhite in the U.S. Through continued releases and active management of habitat, therefore, it is believed that the masked bobwhite can become permanently established at the refuge to ensure its continued survival in the wild.

Zoo Biology↗
USGS2015

Assessment of the use of sorbent amendments for reduction of mercury methylation in wetland sediments at Acadia National Park, Maine

Mercury is a contaminant of ecological concern because of its ubiquity and toxicity to fish and wildlife, and is considered a severe and ongoing threat to biota at Acadia National Park in Maine. The formation and biomagnification of methylmercury is the primary concern of resource managers at Acadia, and information is needed to develop strategies for remediation or mitigation of this contaminant. The U.S. Geological Survey in cooperation with Acadia National Park, National Park Service carried out a series of laboratory and field experiments to evaluate the potential of zero-valent iron and granular activated carbon to reduce the rate of the bacterially mediated process of mercury methylation and subsequent biological uptake by the great pond snail Lymnaea stagnalis . The addition of zero-valent iron resulted in an increase in ferrous iron that was then further oxidized to poorly crystalline amorphous ferric iron, as was anticipated. Our original hypothesis was that these reactions would reduce methylation by decreasing the concentrations of substrates for bacterial methylation (sulfide and divalent mercury) through sorption to ferric iron surfaces, formation of iron sulfide compounds, or conversion of mercury to gaseous forms and subsequent evasion. The results of our experiments did not consistently support this hypothesis. In one experiment the application of zero-valent iron increased the amount of methylmercury associated with surficial sediment. In another experiment zero-valent iron decreased the amount of methylmercury associated with surficial sediment. The addition of zero-valent iron may have stimulated mercury methylation by iron reducing bacteria and if that effect outweighed the processes that could have decreased methylation then methylation would not be decreased. The results of field mesocosm experiments indicated that there was a decreasing trend in pore-water methylmercury concentration after application of granular activated carbon but methylation was not affected because there was no corresponding decrease in sediment methylmercury concentration. The application of granular activated carbon resulted in the sorption of methylmercury. The application of granular activated carbon resulted in an increase in the distribution coefficient for methylmercury indicating that this amendment caused a higher proportion of methylmercury to be associated with the sediment than the pore water in comparison to the reference (untreated) condition. Experiments to test whether zero-valent iron or granular activated carbon would reduce the biouptake of methylmercury in snails were inconsistent; zero-valent iron had no effect on uptake in one experiment but resulted in a significant decrease in uptake in a second experiment. Granular activated carbon did not affect biouptake in either experiment.

Maine↗
USGS2011

Setting limits: Using air pollution thresholds to protect and restore U.S. ecosystems

More than four decades of research provide unequivocal evidence that sulfur, nitrogen, and mercury pollution have altered, and will continue to alter, our nation's lands and waters. The emission and deposition of air pollutants harm native plants and animals, degrade water quality, affect forest productivity, and are damaging to human health. Many air quality policies limit emissions at the source but these control measures do not always consider ecosystem impacts. Air pollution thresholds at which ecological effects are observed, such as critical loads, are effective tools for assessing the impacts of air pollution on essential ecosystem services and for informing public policy. U.S. ecosystems can be more effectively protected and restored by using a combination of emissions-based approaches and science-based thresholds of ecosystem damage. Based on the results of a comprehensive review of air pollution thresholds, we conclude: ??? Ecosystem services such as air and water purification, decomposition and detoxification of waste materials, climate regulation, regeneration of soil fertility, production and biodiversity maintenance, as well as crop, timber and fish supplies are impacted by deposition of nitrogen, sulfur, mercury and other pollutants. The consequences of these changes may be difficult or impossible to reverse as impacts cascade throughout affected ecosystems. ??? The effects of too much nitrogen are common across the U.S. and include altered plant and lichen communities, enhanced growth of invasive species, eutrophication and acidification of lands and waters, and habitat deterioration for native species, including endangered species. ??? Lake, stream and soil acidification is widespread across the eastern United States. Up to 65% of lakes within sensitive areas receive acid deposition that exceeds critical loads. ??? Mercury contamination adversely affects fish in many inland and coastal waters. Fish consumption advisories for mercury exist in all 50 states and on many tribal lands. High concentrations of mercury in wildlife are also widespread and have multiple adverse effects. ??? Air quality programs, such as those stemming from the 1990 Clean Air Act Amendments, have helped decrease air pollution even as population and energy demand have increased. Yet, they do not adequately protect ecosystems from long-term damage. Moreover they do not address ammonia emissions. ??? A stronger ecosystem basis for air pollutant policies could be established through adoption of science-based thresholds. Existing monitoring programs track vital information needed to measure the response to policies, and could be expanded to include appropriate chemical and biological indicators for terrestrial and aquatic ecosystems and establishment of a national ecosystem monitoring network for mercury. The development and use of air pollution thresholds for ecosystem protection and management is increasing in the United States, yet threshold approaches remain underutilized. Ecological thresholds for air pollution, such as critical loads for nitrogen and sulfur deposition, are not currently included in the formal regulatory process for emissions controls in the United States, although they are now considered in local management decisions by the National Park Service and U.S. Forest Service. Ecological thresholds offer a scientifically sound approach to protecting and restoring U.S. ecosystems and an important tool for natural resource management and policy. ?? The Ecological Society of America.

Issues in Ecology↗
USGS2026

Landscape connectivity and wildlife access to water across an international border: Barriers and opportunities for facilitating transboundary movement

Rapid global acceleration in the construction of physical barriers along international borders has greatly influenced biodiversity and animal movement. Physical barriers can fragment landscapes, hinder access to essential resources, impact long-distance migrations, and inhibit dispersal and gene flow. The effects of physical barriers on animal movement and landscape connectivity can be exacerbated in dryland environments where access to water is a limiting factor. In recent decades, the construction of border barrier infrastructure has accelerated along the international boundary between the United States and Mexico. Here, we used a landscape connectivity model to investigate the effects of barriers on wildlife access to the river in the Lower Rio Grande Valley. We used a modified omnidirectional connectivity model to compare access to the river for three large, terrestrial mammal species across three border barrier scenarios: (1) a landscape without border barriers; (2) a landscape with the existing barrier system; and (3) a potential future landscape with a continuous barrier system. The existing barrier system includes many discrete sections of barrier within tracts of the Lower Rio Grande Valley National Wildlife Refuge or on lands associated with the region's flood control system. Our results indicate that the existing border barriers can impede connectivity and wildlife access to the river in some areas, while some existing gaps between border barrier sections can serve as conduits for wildlife movement and river access. Our future scenario results show how a potential continuous border barrier system could further impede wildlife access to the river. We discuss management and landscape conservation options for enhancing wildlife access to water and riverine habitats. Collectively, our results illustrate the potential effects of border barriers on wildlife movement and access to water, providing information that can be used to better anticipate and lessen the ecological impacts of transboundary barriers.

Tamaulipas, Texas↗
USGS2024

Low rate of population establishment of a freshwater invertebrate (Gammarus lacustris) in experimental conservation translocations

Conservation translocations may be a useful tool for the restoration of declining freshwater invertebrates, but they are poorly represented in the literature. We conducted a before-after/control-impact (BACI) experiment to test the efficacy of conservation translocation for re-establishing abundant populations of the amphipod Gammarus lacustris , a declining species and wildlife food resource in depressional wetlands in the upper Midwest of the United States of America. Each study site ( n = 19) contained at least one treatment wetland receiving translocated G. lacustris from a local donor and one control wetland. We selected study wetlands based on a suite of wetland characteristics and randomly assigned recipient versus control treatment. Gammarus lacustris was detected post-translocation at only 2 of 22 recipient wetlands (1 of 19 sites). Overall, there was a statistical increase in G. lacustris density in recipient wetlands compared to controls; however, the results were of minimal biological significance due to being driven by a single site with low G. lacustris densities. Accordingly, our results suggest that future conservation translocations of amphipods might be successful if limited to recently restored wetlands or informed by a more complex habitat suitability model to differentiate dispersal limitations from habitat limitations. To develop such a model would involve identifying the fewest, most influential physical and biological factors (e.g. wetland size/structure, fish, aquatic vegetation, and water chemistry) from the numerous inter-related factors that correlate with the abundance of naturally occurring G. lacustris ; candidate wetlands to receive amphipods would be those for which the model predicts abundant G. lacustris but in which they do not presently occur.

Minnesota↗
USGS2014

BatTool: an R package with GUI for assessing the effect of White-nose syndrome and other take events on Myotis spp. of bats

Background: Myotis species of bats such as the Indiana Bat and Little Brown Bat are facing population declines because of White-nose syndrome (WNS). These species also face threats from anthropogenic activities such as wind energy development. Population models may be used to provide insights into threats facing these species. We developed a population model, BatTool, as an R package to help decision makers and natural resource managers examine factors influencing the dynamics of these species. The R package includes two components: 1) a deterministic and stochastic model that are accessible from the command line and 2) a graphical user interface (GUI). Results: BatTool is an R package allowing natural resource managers and decision makers to understand Myotis spp. population dynamics. Through the use of a GUI, the model allows users to understand how WNS and other take events may affect the population. The results are saved both graphically and as data files. Additionally, R-savvy users may access the population functions through the command line and reuse the code as part of future research. This R package could also be used as part of a population dynamics or wildlife management course. Conclusions: BatTool provides access to a Myotis spp. population model. This tool can help natural resource managers and decision makers with the Endangered Species Act deliberations for these species and with issuing take permits as part of regulatory decision making. The tool is available online as part of this publication.

Source Code for Biology and Medicine↗
USGS2006

Understanding barriers to implementation of an adaptive land management program

The Florida Fish and Wildlife Conservation Commission manages over 650,000 ha, including 26 wildlife management and environmental areas. To improve management, they developed an objective-based vegetation management (OBVM) process that focuses on desired conditions of plant communities through an adaptive management framework. Our goals were to understand potential barriers to implementing OBVM and to recommend strategies to overcome barriers. A literature review identified 47 potential barriers in six categories to implementation of adaptive and ecosystem management: logistical, communication, attitudinal, institutional, conceptual, and educational. We explored these barriers through a bureau-wide survey of 90 staff involved in OBVM and personal interviews with area managers, scientists, and administrators. The survey incorporated an organizational culture assessment instrument to gauge how institutional factors might influence OBVM implementation. The survey response rate was 69%. Logistics and communications were the greatest barriers to implementing OBVM. Respondents perceived that the agency had inadequate resources for implementing OBVM and provided inadequate information. About one-third of the respondents believed OBVM would decrease their job flexibility and perceived greater institutional barriers to the approach. The 43% of respondents who believed they would have more responsibility under OBVM also had greater attitudinal barriers. A similar percentage of respondents reported OBVM would not give enough priority to wildlife. Staff believed that current agency culture was hierarchical but preferred a culture that would provide more flexibility for adaptive management and would foster learning from land management activities. In light of the barriers to OBVM, we recommend the following: (1) mitigation of logistical barriers by addressing real and perceived constraints of staff, funds, and other resources in a participatory manner; (2) mitigation of communication barriers through interpersonal and electronic communication channels; (3) development of an OBVM external advisory committee; and (4) adoption of characteristics of an organizational culture that promotes flexibility and learning. ??2006 Society for Conservation Biology.

Conservation Biology↗
USGS2015

Preliminary methodology to assess the national and regional impact of U.S. wind energy development on birds and bats

The U.S. Geological Survey has developed a methodology to assess the impacts of wind energy development on wildlife; it is a probabilistic, quantitative assessment methodology that can communicate to decision makers and the public the magnitude of these effects on species populations. The methodology is currently applicable to birds and bats, focuses primarily on the effects of collisions, and can be applied to any species that breeds in, migrates through, or otherwise uses any part of the United States. The methodology is intended to assess species at the national scale and is fundamentally different from existing methods focusing on impacts at individual facilities. Publicly available fatality information, population estimates, species range maps, turbine location data, biological characteristics, and generic population models are used to generate both a ranked list of species based on relative risk as well as quantitative measures of the magnitude of the effect on species' population trend and size. Three metrics are combined to determine direct and indirect relative risk to populations. A generic population model is used to estimate the expected change in population trend and includes additive mortality from collisions with wind turbines. Lastly, the methodology uses observed fatalities and an estimate of potential biological removal to assess the risk of a decline in population size. Data for six bird species have been processed through the entire methodology as a test case, and the results are presented in this report. Components of the methodology are based on simplifying assumptions and require information that, for many species, may be sparse or unreliable. These assumptions are presented in the report and should be carefully considered when using output from the methodology. In addition, this methodology can be used to recommend species for more intensive demographic modeling or highlight those species that may not require any additional protection because effects of wind energy development on their populations are projected to be small.

Scientific Investigations Report↗
USGS1986

An overview of raptor conservation in Latin America

Prior to the last decade, biological studies of raptorial birds in Latin America were almost nonexistent. For many species little more was known than their general range and habitat type. The last few years have seen the opening of a door to what will surely be a flood of scientific investigations. Ultimately, the survival of raptor communities in Latin America depends not only on research but also on several other equally significant conservation efforts. These typically appear in the following order: first, appropriate legislation must be enacted and enforced to provide legal protection; second, the public must be educated concerning the value of wildlife; third, substantial blocks of favourable habitat must be identified and preserved; fourth, economic incentives must be generated so that the local human populations actually benefit from the preservation of vulnerable wildlife and natural habitats; and finally, the long-term success of all of these efforts in each nation depends on the attainment of political, economic and social stability.

Birds of Prey Bulletin↗