Search USGS⌕ Search

SEARCH · Search USGS

Results for “North American Birds”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 577 records · Page 32Linked to original sources
USGS1989

Population trends of North American shorebirds based on the International Shorebird Survey

Shorebirds Charadrii are prime candidates for population decline because of their dependence on wetlands that are being lost at a rapid pace. Thirty-six of the 49 species of shorebirds that breed in North America spend most of the year in Latin America. Because populations of most species breed and winter at remote sites, it may be most feasible to monitor their numbers at migration stopovers. In this study, we used statistical trend analysis methods, developed for the North America Breeding Bird Survey, to analyze data on shorebird populations during southbound migration in the United States. Survey data were collected by volunteers in the International Shorebird Survey (ISS). The analyses indicate that whimbrels Numenius phaeopus , short-billed dowitchers Limnodromus griseus , and sanderlings Calidris alba have undergone statistically significant declines. Methodological concerns over both the ISS and the trend analysis procedures are discussed in detail and biological interpretations of the results are suggested.

Biological Conservation↗
USGS2025

Landscape changes and declines in Aquila chrysaetos (Golden Eagle) territory occupancy in southwestern Idaho

Rapid loss of native shrubs and expansion of invasive annual plants like cheatgrass ( Bromus tectorum ) have altered North American shrub-steppe systems across extensive areas. Predators, like Aquila chrysaetos (Golden Eagle) that forage on shrub-reliant prey, may abandon historically occupied territories or increase their territory size to cope with degraded habitat. We used a multiseason Bayesian occupancy model that accounted for imperfect detection to investigate the associations between landscape cover, fire history, conspecific neighbor density, and occupancy of 36 A. chrysaetos territories in southwestern Idaho and the Morley Nelson Snake River Birds of Prey National Conservation Area, USA from 1986 to 2022. The probability of A. chrysaetos occupancy at historically occupied territories decreased 25% from 1986 to 2022 (0.83–0.58). Once territories became vacant for 5 yr, they tended to remain vacant, suggesting that they were no longer suitable for eagles, or that no new eagles were recruiting into the population. Territory occupancy was positively associated with shrub cover ( β : 0.90, 95% CrI: 0.12 to 1.71) and negatively (albeit weakly) associated with annual herbaceous cover ( β : –0.63, 95% CrI: –1.32 to 0.05). Territories closer to other occupied territories had a lower probability of occupancy than territories with distant neighbors ( β : –3.89, 95% CrI: –4.61 to –3.14), likely because eagles compensated for degraded habitat by expanding their territories. Years since the territory last burned had a slightly positive effect on occupancy with high uncertainty and a credible interval that overlapped 0 ( β : 0.28, 95% CrI: –0.26 to 0.87). The probability of detecting eagles in an occupied territory was high (0.90) and improved in surveys conducted earlier in the day and later in the breeding season. Shrub conversion to invasive grasslands has negative bottom-up consequences on A. chrysaetos territory occupancy, which may decrease the local carrying capacity for eagles in this area.

Idaho↗
USGS1974

PCB's and p,p'DDE in the blood of cachectic patients

The pheasant, in its North American range, seems to have had its greatest success in glaciated or in other areas associated with calcareous soils. Success has been slight in areas deficient in calcium.....In Lancaster County, Pennsylvania, no environmental difference other than presence or absence of limestone was discovered that might explain the high population in the limestone valley and the scarcity of pheasants in the non-calcareous Piedmont area....Pheasants at the Patuxent Refuge, when given limestone grit, reproduced successfully on a diet roughly comparable to the natural pheasant diet but failed to reproduce adequately on such a diet when granite grit, instead of limestone, was supplied.....A supplement of powdered calcium carbonate in the diet was adequate t,o permit production of eggs by birds on the granite grit.....Birds receiving granite grit had apparently normal eggs in the ovary but failed to ovulate more than a very few eggs. The precise role of calciun~i n permitting ovulation was not investigated.....It is concluded that calcium, which is low in the natural pheasant diet, must be supplemented in some way to permit pheasants to reproduce. Scarcity of this element in non-calcareous areas may well explain the failure of the pheasant in many parts of North America.

Bulletin of Environmental Contamination and Toxico↗
USGS2026

American kestrel population trends and vital rates at the continental scale

The American kestrel ( Falco sparverius , hereafter referred to as kestrel) has declined across much of its North American range since at least the mid-1960s. Kestrel population dynamics have been explored through a multitude of local studies and two broad reviews of available data. Across large geographic extents, however, the demographic cause(s) of kestrel population declines remain(s) largely unknown. As part of a collaborative effort to elucidate the drivers of kestrel population declines, we developed a continental-scale integrated population model using band-recovery data, productivity data, and Breeding Bird Survey indices from 1986 to 2019 to estimate indices of annual population sizes, survival, and productivity rates across the continental United States. We detected a decline in population size of ~1%–2% per year. Overall estimates of population growth from 1986 to 2019 suggest a 29% decline in population size (95% CI = −34% to −23%). There was little evidence of a trend in brood size. However, survival of juvenile birds (mean = −0.015, SD = 0.008 and mean = −0.024, SD = 0.010 for females and males, respectively) and adult males (mean = −0.016, SD = 0.010) in the summer declined, suggesting that these vital rates could be contributing to declines in populations over time. Winter adult survival rates (mean = −0.004, SD = 0.009 and mean = −0.009, SD = 0.010 for females and males, respectively) also declined but to a lesser extent than summer survival. For juvenile birds, winter survival increased (mean = 0.006, SD = 0.008 and mean = 0.002, SD = 0.009 for females and males, respectively); however, this was not enough to offset declines in summer survival and annual survival rates declined over the time series. Annual adult survival was also low relative to previous research on kestrel survival rates. Given the importance of survival to population trends, our findings provide support for several previously proposed broad classes of factors potentially contributing to observed population declines: declines in arthropod prey, second-generation rodenticides, neonicotinoid insecticides, and predation.

Ecosphere↗
USGS1971

Publication dates of the North American Fauna series

The correct date of publication of numbers in the well-known North American Fauna series, begun in 1889, was printed on the cover of each issue through No. 48. After that time dates of publication that appear on the covers are either incomplete or incorrect. For taxonomic purposes, for developing a chronological survey of a subject, or for other reasons, the exact date of publication of numbers in this important series is useful. We think it important to call attention to the correct dates of publication for numbers beyond 48. Those dealing with birds are listed below by number, followed by the author's name for ease of reference, the date printed on the cover of the issue, and the correct date of publication in parentheses. Numbers not listed do not relate to birds (see J. Mammal., 51: 845, 1970).

The Auk↗
USGS2015

Archiving California’s historical duck nesting data

The U.S. Geological Survey (USGS), in partnership with the California Waterfowl Association (CWA) and other organizations, have compiled large datasets on the nesting ecology and management of dabbling ducks and associated upland nesting birds (Northern Harriers [ Circus cyaneus ], Short-eared Owls [ Asio flammeus ], Ring-necked Pheasants [ Phasianus colchicus ], and American Bitterns [ Botaurus lentiginosus ]) throughout California on Federal Refuges, State Wildlife Areas, and private lands, some participating in State and Federal habitat programs. These datasets encompass several long-term monitoring programs at multiple sites throughout California, and include data from more than 26,000 nests and span nearly 30 years. These historical datasets represent some of the longest term datasets on nesting ducks in North America, if not the world. They are extremely valuable for ongoing waterfowl management and habitat conservation efforts in California, as well as throughout the world. However, without organization and electronic access, these data are an untapped resource and are not being used to the full extent possible. Prior to this project, these datasets were scattered among various agencies and organizations, and original paper nest cards were being stored in cardboard boxes in attics and storage containers that were not suitable for long-term archival storage. In addition, most of these data had not been entered into a computerized database and thus were at high risk for permanent data loss. To protect this irreplaceable dataset, we submitted a series of proposals to obtain funds to complete this data archival project over the past 5 years. The Central Valley Joint Venture, USGS Data Rescue Program, and USGS Ecosystems Mission Area funded this data archival project. In addition, we leveraged other USGS projects on nesting shorebirds, songbirds, and seabirds to use further resources to more fully develop the nest database structure for use on nesting waterfowl. Specifically, this large dataset on ducks was archived by USGS, but the dataset is owned and managed by a consortium of organizations. Therefore, any access and use of this data must occur through the principal investigators, who contributed data and resources to this archival project, as detailed in section, “Data Availability.” With the conclusion of this project, most duck nest data have been entered, but all nest-captured hen data and other breeding waterfowl data that were outside the scope of this project have still not been entered and electronically archived. Maintaining an up-to-date archive will require additional resources to archive and enter the new duck nest data each year in an iterative process. Further, data proofing should be conducted whenever possible, and also should be considered an iterative process as there was sometimes missing data that could not be filled in without more direct knowledge of specific projects. Despite these disclaimers, this duck data archive represents a massive and useful dataset to inform future research and management questions.

California↗
USGS1992

Comparison of neotropical migrant landbird populations wintering in tropical forest, isolated forest fragments, and agricultural habitats

Neotropical migrant bird populations were sampled at 76 sites in seven countries by using mist nets and point counts during a six-winter study. Populations in major agricultural habitats were compared with those in extensive forest and isolated forest fragments. Certain Neotropical migrants, such as the Northern Parula, American Redstart, and the Black-throated Blue, Magnolia, Black-and-white, and Hooded warblers, were present in arboreal agricultural habitats such as pine, cacao, citrus, and shade coffee plantations in relatively large numbers. Many north temperate zone shrub-nesting species, such as the Gray Catbird, White-eyed Vireo, Tennessee Warbler, Common Yellowthroat, and Indigo Bunting, also used agricultural habitats in winter, as did resident hummingbirds and migrant orioles. Ground-foraging migrants, such as thrushes and Kentucky Warblers, were rarely found in the agricultural habitats sampled. Although many Neotropical migrants use some croplands, this use might be severely limited by overgrazing by cattle, by intensive management (such as removal of ground cover in an orchard), or by heavy use of insecticides, herbicides, or fungicides.

Book chapter↗
USGS1987

Population ecology of the mallard VIII: Winter distribution patterns and survival rates of winter-banded mallards

In the present report we address questions about winter distribution patterns and survival rates of North American mallards Anas platyrhynchos . Inferences are based on analyses of banding and recovery data from both winter and preseason banding period. The primary wintering range of the mallard was dividded into 45 minor reference areas and 15 major reference areas which were used to summarize winter banding data. Descriptive tables and figures on the recovery distributions of winter-banded mallards are presented. Using winter recoveries of preseason-banded mallards, we found apparent differences between recovery distribution of young versus adult birds from the same breeding ground reference areas. However, we found no sex-specific differences in winter recovery distribution patterns. Winter recovery distributions of preseason-banded birds also provided evidence that mallards exhibited some degree of year-to-year variation in wintering ground location. The age- and sex-specificity of such variation was tested using winter recoveries of winter-banded birds, and results indicated that subadult (first year) birds were less likely to return to the same wintering grounds the following year than adults. Winter recovery distributions of preseason-banded mallards during 1950-58 differed from distributions in 1966-76. These differences could have resulted from either true distributional shifts or geographic changes in hunting pressure. Survival and recovery rates were estimated from winter banding data. We found no evidence of differences in survival or recovery rates between subadult and adult mallards. Thus, the substantial difference between survival rates of preseason-banded young and adult mallards must result almost entirely from higher mortality of young birds during the approximate period, August-January. Male mallards showed higher survival than females, corroborating inferences based on preseason data. Tests with winter banding and band recovery data indicated some degree of year-to-year variation in both survival and recovery rates, a result again consistent with inference from preseason data. Some evidence indication geographic variation in survival rates; however, there were no consistent directional differences between survival rates of mallards from adjacent northern versus southern areas, or eastern versus western areas. In some comparisons, Central Flyway mallards exhibited slightly higher survival rates than mallards from other flyways. Weighted mean estimates of continental survival rates were computed for the period 1960-77 from both winter banding data and preseason banding of adults. Resulting estimates differed significantly for males, but not for females, and the magnitude of the difference between point estimates was relatively small, even for males. The direction of the difference between these estimates was predicted correctly from previous work on the effects of heterogeneous survival an d recovery rates on band recovery model estimates. The similarity of survival estimates from these two independent data sets supports the believe that biases in these estimates are relatively small.

Resource Publication↗
USGS2015

Global trends in emerging viral diseases of wildlife origin

Fifty years ago, infectious diseases were rarely considered threats to wildlife populations, and the study of wildlife diseases was largely a neglected endeavor. Furthermore, public health leaders at that time had declared that “it is time to close the book on infectious diseases and the war against pestilence won,” a quote attributed to Dr. William H. Stewart in 1967. There is some debate whether he actually said these words; however, they reflect the widespread belief at that time (Spellberg, 2008). Leap forward to today, and the book on infectious diseases has been dusted off. There is general consensus that the global environment favors the emergence of infectious diseases, and in particular, diseases of wildlife origin (Taylor et al., 2001). Examples of drivers of these infectious diseases include climate and landscape changes, human demographic and behavior changes, global travel and trade, microbial adaptation, and lack of appropriate infrastructure for wildlife disease control and prevention (Daszak et al., 2001). The consequences of these emerging diseases are global and profound with increased burden on the public health system, negative impacts on the global economy and food security, declines and extinctions of wildlife species, and subsequent loss of ecosystem integrity. For example, 35 million people are currently living with HIV infection globally (http://www.who.int/gho/hiv/en); 400 million poultry have been culled since 2003 as a result of efforts to control highly pathogenic H5N1 avian influenza (http://www.fao.org/avianflu/en/index.html), and there are increasing biological and ecological consequences. Examples of health threats to biodiversity include the “spillover” of human diseases to great ape populations (Köndgen et al., 2008), the near-extirpation of the black-footed ferret from canine distemper and sylvatic plague (for a review see Abbott et al., 2012), and threats to Hawaiian forest birds from introduced pathogens such as avian malaria and avian pox (van Riper et al., 1986, 2002). There are also newly discovered pathogens or diseases that have resulted in population declines, and global extinctions of several species. Examples include Batrachochytrium dendrobatidis, which causes a cutaneous fungal infection of amphibians and is linked to declines of amphibians globally (Kriger and Hero, 2009); and recently discovered Pseudogymnoascus (Geomyces) destructans, the etiologic agent of white-nose syndrome (WNS), which has caused precipitous declines of North American bat species (Blehert et al., 2009). Furthermore, there is increasing evidence of the subsequent impacts on human and ecosystem health; for example, increasing risk of exposure to Lyme disease as a consequence of decreased biodiversity (LoGiudice et al., 2003) as well as the economic cost of the loss of bats due to decreased insect control services (Boyles et al., 2011). Figure A12-1 is a timeline of important diseases investigated by the U.S. Geological Survey since the 1970s, which illustrates three factors: 1. The unprecedented emergence of new pathogens and geographic spread of known pathogens since the 1990s; 2. Diseases are increasingly causing large-scale, negative impacts on wildlife populations and spreading over larger geographic areas rather than remaining localized; and 3. Diseases are increasingly of concern for multiple sectors, including public health, agriculture and wildlife management agencies. Of increasing concern are these novel diseases such as WNS as they are hard to anticipate, particularly devastating to human health or wildlife populations, challenging to manage, spread over large geographic areas in short time periods, and may result in ecological ripple effects that are difficult to predict. The following article provides examples of recently emerged viral diseases of wildlife origin. The examples have been selected to illustrate the drivers of emerging viral diseases, both novel pathogens and previously known diseases, the impacts of these diseases, as well as the role of wildlife both as “villains” or reservoirs as well as “victims” of these viral diseases. The article also discusses potential management strategies for emerging viral diseases in wildlife populations and future science directions in wildlife health to prevent, prepare, respond to, and recover from these disease events. Finally, the concept of One Health and its potential role in developing solutions to these issues of mutual concern is discussed.

Conference Paper↗
USGS1972

Egg measurements for three endangered species

From 1967 through 1969, external dimensions of the eggs of three endangered species of birds were measured. Included were 33 eggs of the Whooping Crane ( Grus americana ), 158 eggs of the Aleutian Canada Goose ( Branta canadensis leucopareia ), and 809 eggs of the Masked Bobwhite Quail ( Colinus virginiana ridgwayi ). In the literature, there are only scattered reports of small samples of Masked Bobwhite Quail and Whooping Crane eggs and, to the best of our knowledge, no measurements of Aleutian Canada Goose eggs have been reported. The information presented herein is intended to augment knowledge of these three threatened forms of North American wildlife. We wish to thank members of the staff of the Endangered Wildlife Re- search Program for assistance in gathering the data.

The Auk↗
USGS2016

Genetic structure of faucet snail, Bithynia tentaculata populations in North Americal based on microsattelite markers

Bithynia tentaculata is believed to have been extirpated from North America during the last glacial maximum. It was reintroduced into North America via the Great Lakes basin in the 1800’s and has recently been expanding its geographic range. This snail serves as intermediate host for three trematodes that cause extensive recurring morbidity and mortality events in migratory water birds along the Mississippi River. Using twelve microsatellite loci for ~200 individual snails from 11 populations in North America and Europe, we examined one of the three major geographic regions from which founding populations into the Great Lakes typically originate. Our data supports a single recolonization of North America into the Great Lakes Basin followed by subsequent introduction events from the Great Lakes to other large watersheds in North America. However, additional watersheds in Europe require sampling to confirm this result. No populations with genetic signatures indicative of North American glacial relics were found. The initial invasion of North America was likely not from the Ponto-Caspian basin, the usual source of freshwater invasive species to the Laurentian Great Lakes.

Freshwater Mollusk Biology and Conservation↗
USGS1958

Calcium, phosphorus and protein levels as factors in the distribution of the pheasant

Summary of work on pheasant nutrition conducted since 1949 at the Patuxent Research Refuge. Pheasant chicks fed experimental diets failed to develop normally on protein levels of 15 and 18%. With 22% protein they grew at a reduced rate as compared to those on 28%. Protein level of the reproductive diet was shown to be important; low production of eggs and young resulted from levels below 25%. Calcium was found to be even more critical than protein level for reproduction; birds on a winter diet that furnished 145 mg./kg. per day had poor reproductive success the following spring. About 600 mg./kg. of Ca per day was necessary in the reproduction diet. Birds on an intermediate level of Ca (about 0.5% of diet) showed evidence of cumulative deficiency. It was concluded that pheasants receiving levels of Ca no higher than 0.5% in nature might display 'straggling failure' such as has been observed in several midwestern areas.

Transactions of the North American Wildlife Confer↗
USGS2008

Contaminant levels in eggs of American white pelicans, Pelecanus erythrorhynchos, from Chase Lake, North Dakota

American White Pelicans (Pelecanus erythrorhynchos) are colonial nesters, making them susceptible to site-specific mortality factors. One of the largest known breeding colonies is at Chase Lake National Wildlife Refuge in North Dakota. In 2004, this colony suffered total reproductive failure. In 2005, we collected abandoned eggs from this colony to test for environmental contaminants. Nine eggs were analyzed for 28 organochlorine pesticides, total polychlorinated biphenyls, and 26 inorganic elements. Based on concentrations in this sample of eggs and levels linked to reproductive problems in birds, adult pelicans in the Chase Lake breeding colony are not at known risk from any of the environmental contaminants we measured.

North Dakota↗
USGS2020

Direct and indirect effects of a keystone engineer on a shrubland-prairie food web

Keystone engineers are critical drivers of biodiversity throughout ecosystems worldwide. Within the North American Great Plains, the black‐tailed prairie dog is an imperiled ecosystem engineer and keystone species with well‐documented impacts on the flora and fauna of rangeland systems. However, because this species affects ecosystem structure and function in myriad ways (i.e., as a consumer, a prey resource, and a disturbance vector), it is unclear which effects are most impactful for any given prairie dog associate. We applied structural equation models (SEM) to disentangle direct and indirect effects of prairie dogs on multiple trophic levels (vegetation, arthropods, and birds) in the Thunder Basin National Grassland. Arthropods did not show any direct response to prairie dog occupation, but multiple bird species and vegetation parameters were directly affected. Surprisingly, the direct impact of prairie dogs on colony‐associated avifauna (Horned Lark [ Eremophila alpestris ] and Mountain Plover [ Charadrius montanus ]) had greater support than a mediated effect via vegetation structure, indicating that prairie dog disturbance may be greater than the sum of its parts in terms of impacts on localized vegetation structure. Overall, our models point to a combination of direct and indirect impacts of prairie dogs on associated vegetation, arthropods, and avifauna. The variation in these impacts highlights the importance of examining the various impacts of keystone engineers, as well as highlighting the diverse ways that black‐tailed prairie dogs are critical for the conservation of associated species.

Wyoming↗
USGS2022

Proceedings of the Highly Pathogenic Avian Influenza and Wild Birds Webinar Series, August 2–5, 2021

In light of ongoing and geographically widespread highly pathogenic avian influenza (HPAI) outbreaks in wild birds throughout much of Eurasia during 2020–21, the Interagency Steering Committee for Avian Influenza Surveillance in Wild Migratory Birds disseminated an informational memorandum in January 2021 to highlight the need for enhanced surveillance and heightened awareness in North America. This was followed by coordination of this August 2021 international HPAI webinar series facilitated by the U.S. Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) Veterinary Services Training Program. In addition to heightening awareness, the webinars provided an opportunity for information exchange and facilitated virtual discussions between Federal, State, academic, and international partners on the ongoing Eurasian outbreak, lessons learned from the 2014–15 North American HPAI outbreak, and associated challenges and opportunities.

Open-File Report↗
USGS2007

Modeling tradeoffs in avian life history traits and consequences for population growth

Variation in population dynamics is inherently related to life history characteristics of species, which vary markedly even within phylogenetic groups such as passerine birds. We computed the finite rate of population change (??) from a matrix projection model and from mark-recapture observations for 23 bird species breeding in northern Arizona. We used sensitivity analyses and a simulation model to separate contributions of different life history traits to population growth rate. In particular we focused on contrasting effects of components of reproduction (nest success, clutch size, number of clutches, and juvenile survival) versus adult survival on ??. We explored how changes in nest success or adult survival coupled to costs in other life history parameters affected ?? over a life history gradient provided by our 23 Arizona species, as well as a broader sample of 121 North American passerine species. We further examined these effects for more than 200 passeriform and piciform populations breeding across North America. Model simulations indicate nest success and juvenile survival exert the largest effects on population growth in species with moderate to high reproductive output, whereas adult survival contributed more to population growth in long-lived species. Our simulations suggest that monitoring breeding success in populations across a broad geographic area provides an important index for identifying neotropical migratory populations at risk of serious population declines and a potential method for identifying large-scale mechanisms regulating population dynamics. ?? 2007 Elsevier B.V. All rights reserved.

Ecological Modelling↗
USGS2013

Case study: Prioritization strategies for reforestation of minelands to benefit Cerulean Warblers

The central Appalachian landscape is being heavily altered by surface coal mining. The practice of Mountaintop Removal/Valley Fill (MTRVF) mining has transformed large areas of mature forest to non-forest and created much forest edge, affecting habitat quality for mature forest wildlife. The Appalachian Regional Reforestation Initiative is working to restore mined areas to native hardwood forest conditions, and strategies are needed to prioritize restoration efforts for wildlife. We present mineland reforestation guidelines for the imperiled Cerulean Warbler, considered a useful umbrella species, in its breeding range. In 2009, we surveyed forest predicted to have Cerulean Warblers near mined areas in the MTRVF region of West Virginia and Kentucky. We visited 36 transect routes and completed songbird surveys on 151 points along these routes. Cerulean Warblers were present at points with fewer large-scale canopy disturbances and more mature oak-hickory forest. We tested the accuracy of a predictive map for this species and demonstrated that it can be useful to guide reforestation efforts. We then developed a map of hot spot locations that can be used to determine potential habitat suitability. Restoration efforts would have greatest benefit for Cerulean Warblers and other mature forest birds if concentrated near a relative-abundance hot spot, on north- and east-facing ridgetops surrounded by mature deciduous forest, and prioritized to reduce edges and connect isolated forest patches. Our multi-scale approach for prioritizing restoration efforts using an umbrella species may be applied to restore habitat impacted by a variety of landscape disturbances.

Journal American Society of Mining and Reclamation↗
USGS1994

Emperor goose (Chen canagica)

Early naturalists exploring western Alaska were intrigued to find a stocky, blue-gray species of coastal goose unique to that area and nearby Russia. As E. W. Nelson (1887) wrote, "Among the various species of birds more or less peculiar to Alaska this goose is perhaps the most noteworthy." The Emperor Goose nests in the extensive coastal salt marsh habitats of arctic and sub-arctic Alaska and Russia and winters primarily on coastal beaches along ice-free areas of the Aleutian Islands and the Alaska Peninsula. Locally known as the "Beach Goose" from its habit of roosting and feeding near the waters' edge, the diet of this species consists largely of clams, mussels, and algae when wintering and staging in marine and estuarine habitats. When nesting in terrestrial habitats, it eats mostly roots, bulbs, and shoots of vegetation. Although the breeding biology and habitat requirements of this goose have been examined in detail, mostly on the Yukon-Kuskokwim Delta (Y-K Delta) of Alaska, there have been no intensive studies of its wintering or staging biology. Recent studies of migration have confirmed pathways and timing between the Y-K Delta and staging areas on the Alaska Peninsula and wintering areas largely on the Aleutian Islands (Hupp et al. 2007). Observations of substantial molt migrations to the Chukotka Peninsula in eastern Russia (Hupp et al. 2007) suggest a possible change in distribution, or at least a clarification, and raise the possibility of harvest mortality on both continents. Alaska's Emperor Goose population declined precipitously from 139,000 in 1964 to 42,000 in 1986, although its numbers have recovered slightly since then (Fischer et al. 2008). The factors responsible for this quick decline and slow recovery remain poorly known. Hunting, especially subsistence hunting by Native Americans, is probably a factor (Hupp et al. 2008b); coastal oil pollution could also be reducing the survival of overwintering individuals (Byrd et al. 1995); and interspecific competition among brood rearing geese may limit recovery through recruitment (Schmutz and Laing 2002, Lake et al. 2008).

Birds of North America↗