Geology Reports⌕ Search

SEARCH · Geology Reports

Results for “Bird Populations”

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 1,027 records · Page 57Linked to original sources
USGS1995

[Book review] Skua and penguin: Predator and prey

The skua and penguin with title billing in this book are specifically the South Polar Skua ( Catharacta maccormicki ) and the Adélie Penguin ( Pygoscelis adeliae ), More specifically, they are the populations of those two species that breed at Cape Bird on Ross Island, Antarctica (77°14'S, 16628'E), where the author and his students and colleagues conducted research during 1965-1970, Young presents the results of that research (with apologies for the long delay), using later research conducted by others on these species to help evaluate and interpret the findings from his program,

The Auk↗
USGS2017

Program MAMO: Models for avian management optimization-user guide

The following chapters describe the structure and code of MAMO, and walk the reader through running the different components of the program with sample data. This manual should be used alongside a computer running R, so that the reader can copy and paste code into R, observe the output, and follow along interactively. Taken together, chapters 2–4 will allow the user to replicate a simulation study investigating the consequences of climate change and two potential management actions on the population dynamics of a vulnerable and iconic Hawaiian forest bird, the ‘I‘iwi (Drepanis coccinea; hereafter IIWI).

Technical Report↗
USGS2013

Golden eagle population trends in the western United States: 1968-2010

In 2009, the United States Fish and Wildlife Service promulgated permit regulations for the unintentional lethal take (anthropogenic mortality) and disturbance of golden eagles (Aquila chrysaetos). Accurate population trend and size information for golden eagles are needed so agency biologists can make informed decisions when eagle take permits are requested. To address this need with available data, we used a log-linear hierarchical model to average data from a late-summer aerial-line-transect distance-sampling survey (WGES) of golden eagles in the United States portions of Bird Conservation Region (BCR) 9 (Great Basin), BCR 10 (Northern Rockies), BCR 16 (Southern Rockies/Colorado Plateau), and BCR 17 (Badlands and Prairies) from 2006 to 2010 with late-spring, early summer Breeding Bird Survey (BBS) data for the same BCRs and years to estimate summer golden eagle population size and trends in these BCRs. We used the ratio of the density estimates from the WGES to the BBS index to calculate a BCR-specific adjustment factor that scaled the BBS index (i.e., birds per route) to a density estimate. Our results indicated golden eagle populations were generally stable from 2006 to 2010 in the 4 BCRs, with an estimated average rate of population change of −0.41% (95% credible interval [CI]: −4.17% to 3.40%) per year. For the 4 BCRs and years, we estimated annual golden eagle population size to range from 28,220 (95% CI: 23,250–35,110) in 2007 to 26,490 (95% CI: 21,760–32,680) in 2008. We found a general correspondence in trends between WGES and BBS data for these 4 BCRs, which suggested BBS data were providing useful trend information. We used the overall adjustment factor calculated from the 4 BCRs and years to scale BBS golden eagle counts from 1968 to 2005 for the 4 BCRs and for 1968 to 2010 for the 8 other BCRs (without WGES data) to estimate golden eagle population size and trends across the western United States for the period 1968 to 2010. In general, we noted slightly declining trends in southern BCRs and slightly increasing trends in northern BCRs. However, we estimated the average rate of golden eagle population change across all 12 BCRs for the period 1968–2010 as +0.40% per year (95% CI = −0.27% to 1.00%), suggesting a stable population. We also estimated the average rate of population change for the period 1990–2010 was +0.5% per year (95% CI = −0.33% to 1.3%). Our annual estimates of population size for the most recent decade range from 31,370 (95% CI: 25,450–39,310) in 2004 to 33,460 (95% CI: 27,380–41,710) in 2007. Our results clarify that golden eagles are not declining widely in the western United States. © 2013 The Wildlife Society.

Arizona;California;Colorado;Idaho;Iowa;Kansas;Minn↗
USGS2025

Population estimates and land cover use of wintering Mountain Plovers in Texas

Conservation of migratory birds throughout the full annual cycle requires a comprehensive understanding of abundance and distribution in interconnected breeding, migration, and wintering habitats. The Mountain Plover ( Anarhynchus montanus ) is a rare endemic breeder of the Rocky Mountain and Great Plains regions that migrates to wintering grounds in the southwestern USA and northern Mexico. Information regarding its wintering abundance and distribution, particularly in Texas, is limited. This study provides the first population estimate for Mountain Plovers wintering in Texas and examines factors influencing their land cover use. Through distance sampling surveys in six ecoregions of Texas, we estimated an annual wintering population of 3096 (95% CI 1464–6547) Mountain Plovers during 2019–2020, with the greatest abundances in the Southern Texas Plains and Western Gulf Coastal Plain ecoregions. The highest plover densities were in the Southern Texas Plains and Central Great Plains ecoregions. Most plovers were found in cultivated crops, particularly tilled fields and sod farms, and plovers preferentially selected crop fields without residual vegetation or stubble. Grass/hay fields were used less, perhaps because of tall vegetation. Our findings highlight the significance of Texas as a wintering area for Mountain Plovers and emphasize the importance of specific cropland habitats for this species. These results provide crucial insights for conservation and management efforts aimed at protecting Mountain Plovers throughout their annual cycle.

Texas↗
USGS2000

An evaluation strategy for conservation goals of the Mississippi Alluvial Valley

The population goals and habitat objectives established by the Mississippi Alluvial Valley Migratory Bird Initiative are based on several unverified assumptions. We have developed an evaluation strategy that identifies research needed to verify these assumptions. We also have outlined a monitoring strategy designed to track progress toward achieving habitat objectives and population goals.

Book chapter↗
USGS2026

Bird breeding success in restored grasslands compared to croplands and natural grasslands: A meta-analysis

Reproductive success is central to long-term population persistence, yet it is rarely assessed in ecosystem restoration. We performed a multilevel meta-analysis to assess whether bird breeding success increases from croplands to restored grasslands or from restored grasslands to natural grasslands. We quantified five comparisons of two breeding success variables between croplands and restored grasslands in three species, and 228 comparisons of nine variables between natural and restored grasslands in 22 species using 14 datasets from North America and Europe. For the few grassland birds that nest in croplands, clutch size was higher in restored fields than in croplands. Most importantly, breeding success did not differ between restored and natural grasslands in nine species and for all species combined. In 13 species, breeding success differed between restored and natural grasslands, and it was often higher in restored grasslands during early breeding stages, but higher in natural grasslands during later stages. Eight species did better in restored grasslands (Clay-colored Sparrow, Dickcissel, Eastern Meadowlark, Lesser Prairie-chicken, Mourning Dove, Red-winged Blackbird, Sprague's Pipit, Western Meadowlark), whereas four species did better in natural grasslands (Baird's Sparrow, Common Nighthawk, Lark Bunting, Savannah Sparrow). Our results suggest that bird breeding success can be as high in restored grasslands as in natural ones, and certainly higher than in croplands. While restored grasslands differ widely by geography, climate, method and management, our results offer hope for ecosystem restoration. However, the differences found also imply that species requirements should be considered in grassland ecosystem restoration and management.

Biological Conservation↗
USGS2014

Chromic and iron oxides as fecal markers to identify individual whooping cranes

The whooping crane ( Grus americana ) is listed as endangered under the IUCN Red List, the United States Endangered Species Act, and the Canadian Species at Risk Act (BirdLife International 2012, CWS and USFWS 2007). A major focus of recovery efforts for this endangered species is reintroduction to establish new populations (CWS and USFWS 2007). Captive populations are critical as a source of individuals for reintroduction efforts and also serve as insurance populations. Currently, there are a total of 157 whooping cranes held in captive breeding centers across North America, with the largest at the USGS Patuxent Wildlife Research Center (PWRC) in Laurel, Maryland. Birds produced in this facility are currently being released as part of efforts to establish the Eastern Migratory Population (EMP, Urbanek et al. 2005) and in an effort to establish a non-migratory population in Louisiana. In the past decade, PWRC has produced and released annually an average of 18 birds into the wild; however, reproductive performance of birds at this facility is lower than desired. PWRC had a 60% fertility rate for eggs laid from 2000 through 2010 (J. N. Chandler, personal communication, 2011). Furthermore, reproductive onset in this captive population appears to be delayed compared to wild populations. In wild populations, reproductive onset (production of sperm and eggs) normally occurs ~5 years of age in both males and females, ~2 years after initial pair formation occurs (Ellis et al., 1996), while some females in the EMP have laid eggs earlier than 5 years of age (Converse et al. 2011). However, PWRC females in some cases do not start to lay eggs until 7 years of age (Mirande et al. 1996). Currently, the PWRC population consists of a total of 74 whooping cranes, including 22 pairs. Six of these pairs (27%) are consistently infertile (i.e., no production of fertile eggs) and 3 other pairs (14%) have low fertility (30- 45% fertility in eggs laid), which is variable from year to year. Six pairs (27%) are recently formed and have not produced eggs, and so have unknown fertility. This leaves only 7 pairs (33%) which contribute maximally to PWRC’s chick production (J. N. Chandler, personal communication, 2011). Because of the challenges occurring within this captive colony, PWRC and Smithsonian National Zoo have initiated a joint research project to identify potential underlying causes of poor reproduction in captive whooping cranes.

Conference Paper↗
USGS2011

Geographic variation in morphology of Alaska-breeding Bar-tailed Godwits ( Limosa lapponica ) is not maintained on their nonbreeding grounds in New Zealand

Among scolopacid shorebirds, Bar-tailed Godwits ( Limosa lapponica ) have unusually high intra- and intersexual differences in size and breeding plumage. Despite historical evidence for population structure among Alaska-breeding Bar-tailed Godwits ( L. l. baueri ), no thorough analysis, or comparison with the population's nonbreeding distribution, has been undertaken. We used live captures, field photography, museum specimens, and individuals tracked from New Zealand to describe geographic variation in size and plumage within the Alaska breeding range. We found a north-south cline in body size in Alaska, in which the smallest individuals of each sex occurred at the highest latitudes. Extent of male breeding plumage (proportion of nonbreeding contour feathers replaced) also increased with latitude, but female breeding plumage was most extensive at mid-latitudes. This population structure was not maintained in the nonbreeding season: morphometrics of captured birds and timing of migratory departures indicated that individuals from a wide range of breeding latitudes occur in each region and site in New Zealand. Links among morphology, phenology, and breeding location suggest the possibility of distinct Alaska breeding populations that mix freely in the nonbreeding season, and also imply that the strongest selection for size occurs in the breeding season.

The Auk↗
USGS2006

Demography, genetics, and the value of mixed messages

Iverson et al. (2004) used estimates of the homing rate for molting adult Harlequin Ducks ( Histrionicus histrionicus ) in Alaska to draw inferences about population structure. Homing rates, defined as one minus the ratio of birds recaptured elsewhere to those recaptured at the original banding site, were high (0.95–1.00) for males and females. Iverson et al. (2004) concluded that these high rates of homing are indicative of demographic independence among molting groups separated by small distances (tens to hundreds of kilometers) and that conservation efforts should recognize this fine-scale population structure. We re-examined their use of the homing rate, because their assumption of equal detection probability across a wide sampling area could have led to an upward bias in their estimates of site fidelity. As a result, we are hesitant to agree with their conclusion of high adult homing to molting areas and that molt-site fidelity is evidence for demographic independence. Our hesitancy stems from the fact that little is known about juvenile and adult movements within and among years, breeding area origins, and the variation of demographic parameters (e.g., survival and productivity) among molting groups. Furthermore, population genetic data of these molting groups suggest gene flow at both nuclear and mitochondrial loci. Such mixed messages between demographic (i.e., banding) and genetic data are increasingly common in ornithological studies and offer unique opportunities to reassess predictions and make more robust inferences about population structure across broad temporal and spatial scales. Thus, we stress that it is this broader scale perspective, which combines both demography and genetics, that biologists should seek to quantify and conservation efforts should seek to recognize.

Condor↗
USGS2018

Estimating apparent survival of songbirds crossing the Gulf of Mexico during autumn migration

Many migratory bird species are declining, and the migratory period may limit populations because of the risk in traversing large geographical features during passage. Using automated radio-telemetry, we tracked 139 Swainson's thrushes ( Catharus ustulatus ) departing coastal Alabama, USA and crossing the Gulf of Mexico to arrive in the Yucatan Peninsula, Mexico during autumn. We estimated apparent survival and examined how extrinsic (weather variables and day of year) and intrinsic (fat load, sex and age) factors influenced survival using a mark-recapture approach. We also examined how favourability of winds for crossing the Gulf varied over the past 25 years. Fat load, day of year and wind profit were important factors in predicting which individuals survived crossing the Gulf. Survival estimates varied with wind profit and fat, but generally, fat birds departing on days with favourable wind profits had an apparent survival probability of greater than 0.90, while lean individuals with no or negative wind profits had less than 0.33. The proportion of favourable nights varied within and among years, but has increased over the last 25 years. While conservation strategies cannot improve extrinsic factors, they can provide opportunities for birds to refuel before crossing large geographical features through protecting and creating high-quality stopover sites.

Gulf of Mexico↗
USGS2010

Avian malaria Plasmodium relictum in native Hawaiian forest birds: epizootiology and demographic impacts on ‵apapane Himatione sanguinea

The role of introduced avian malaria Plasmodium relictum in the decline and extinction of native Hawaiian forest birds has become a classic example of the potential effect of invasive diseases on biological diversity of naïve populations. However, empirical evidence describing the impact of avian malaria on fitness of Hawai‵i's endemic forest birds is limited, making it difficult to determine the importance of disease among the suite of potential limiting factors affecting the distribution and abundance of this threatened avifauna. We combined epidemiological force-of-infection with multistate capture––recapture models to evaluate a 7-year longitudinal study of avian malaria in ‵apapane, a relatively common native honeycreeper within mid-elevation Hawaiian forests. We found that malaria transmission was seasonal in this mid-elevation forest; transmission peaked during fall and during some years produced epizootic mortality events. Estimated annual mortality of hatch-year birds typically exceeded 50% and mortality of adults exceeded 25% during epizootics. The substantial impact of avian malaria on this relatively common native species demonstrates the key role this disease has played in the decline and extinction of Hawaiian forest birds.

Journal of Avian Biology↗
USGS2018

Making do with less: Must sparse data preclude informed harvest strategies for European waterbirds?

The demography of many European waterbirds is not well understood because most countries have conducted little monitoring and assessment, and coordination among countries on waterbird management has little precedent. Yet intergovernmental treaties now mandate the use of sustainable, adaptive harvest strategies, whose development is challenged by a paucity of demographic information. In this study, we explore how a combination of allometric relationships, fragmentary monitoring and research information, and expert judgment can be used to estimate the parameters of a theta-logistic population model, which in turn can be used in a Markov decision process to derive optimal harvesting strategies. We show how to account for considerable parametric uncertainty, as well as for different management objectives. We illustrate our methodology with a poorly understood population of taiga bean geese ( Anser fabalis fabalis ), which is a popular game bird in Fennoscandia. Our results for taiga bean geese suggest that they may have demographic rates similar to other, well-studied species of geese, and our model-based predictions of population size are consistent with the limited monitoring information available. Importantly, we found that by using a Markov decision process, a simple scalar population model may be sufficient to guide harvest management of this species, even if its demography is age-structured. Finally, we demonstrated how two different management objectives can lead to very different optimal harvesting strategies, and how conflicting objectives may be traded off with each other. This approach will have broad application for European waterbirds by providing preliminary estimates of key demographic parameters, by providing insights into the monitoring and research activities needed to corroborate those estimates, and by producing harvest management strategies that are optimal with respect to the managers’ objectives, options, and available demographic information.

Ecological Applications↗
USGS1998

An individual-based, spatially-explicit simulation model of the population dynamics of the endangered red-cockaded woodpecker, Picoides borealis

Spatially-explicit population models allow a link between demography and the landscape. We developed a spatially-explicit simulation model for the red-cockaded woodpecker, Picoides borealis , an endangered and territorial cooperative breeder endemic to the southeastern United States. This kind of model is especially appropriate for this species because it can incorporate the spatial constraints on dispersal of helpers, and because territory locations are predictable. The model combines demographic data from a long-term study with a description of the spatial location of territories. Sensitivity analysis of demographic parameters revealed that population stability was most sensitive to changes in female breeder mortality, mortality of female dispersers and the number of fledglings produced per brood. Population behavior was insensitive to initial stage distribution; reducing the initial number of birds by one-half had a negligible effect. Most importantly, we found that the spatial distribution of territories had as strong an effect on response to demographic stochasticity as territory number. Populations were stable when territories were highly aggregated, with as few as 49 territories. When territories were highly dispersed, more than 169 territories were required to achieve stability. Model results indicate the importance of considering the spatial distribution of territories in management plans, and suggest that this approach is worthy of further development.

North Carolina↗
USGS1997

Seasonal and annual survival of adult Pacific brant

Declining mid-winter counts of Pacific brant ( Branta bernicla nigricans ) and reduced numbers of nesting birds on their main breeding grounds prompted us to assess factors that may be limiting recovery of this population. We estimated seasonal and annual survival rates of adult brant in 1986-93 from resightings of leg-banded birds. Brant were banded at a major colony on the Yukon-Kuskokwim Delta, Alaska (Y-K Delta) in 1986-92, and resighted there in 1987-93 as well as at major fall and spring migration and wintering areas in 1990-93. Seasonal survival was the same for males and females. Mean monthly survival rate was lowest (P ≤ 0.05) in late spring migration (15 Apr-1 Jun), the period of greatest subsistence harvest on the breeding grounds, and highest in winter (1 Jan-1 Mar), the period of greatest sport harvest. Annual survival rate did not vary among years (F = 0.51; 5, 718 df; P = 0.91) and averaged 0.840 (SE = 0.031) from 1986 to 1993. Subsistence harvest has contributed to low population levels of Pacific brant.

Alaska↗
USGS2009

Filling a void: abundance estimation of North American populations of arctic geese using hunter recoveries

We consider use of recoveries of marked birds harvested by hunters, in conjunction with continental harvest estimates, for drawing inferences about continental abundance of a select number of goose species. We review assumptions of this method, a version of the Lincoln?Petersen approach, and consider its utility as a tool for making decisions about harvest management in comparison to current sources of information. Finally, we compare such estimates with existing count data, photographic estimates, or other abundance estimates. In most cases, Lincoln estimates are far higher than abundances assumed or perhaps accepted by many waterfowl biologists and managers. Nevertheless, depending on the geographic scope of inference, we suggest that this approach for abundance estimation of arctic geese may have usefulness for retrospective purposes or to assist with harvest management decisions for some species. Lincoln?s estimates may be as close or closer to truth than count, index, or photo data, and can be used with marking efforts currently in place for estimation of survival and harvest rates. Although there are bias issues associated with estimates of both harvest and harvest rate, some of the latter can be addressed with proper allocation of marks to spatially structured populations if subpopulations show heterogeneity in harvest rates.

Book chapter↗
USGS2021

American Woodcock singing-ground survey: Comparison of four models for trend in population size

Wildlife biologists monitor the status and trends of American woodcock Scolopax minor populations in the eastern and central United States and Canada via a singing-ground survey, conducted just after sunset along roadsides in spring. Annual analyses of the survey produce estimates of trend and annual indexes of abundance for 25 states and provinces, management regions, and survey-wide. In recent years, researchers have used a log-linear hierarchical model that defines year effects as random effects in the context of a slope parameter (the S model) to model population change. Recently, researchers have proposed alternative models suitable for analysis of singing-ground survey data. Analysis of a similar roadside survey, the North American Breeding Bird Survey, has indicated that alternative models are preferable for almost all species analyzed in the Breeding Bird Survey. Here, we use leave-one-out cross-validation to compare model fit for the present singing-ground survey model to fits of three alternative models, including a model that describes population change as the difference in expected counts between successive years (the D model) and two models that include t -distributed extra-Poisson overdispersion effects (H models) as opposed to normally distributed extra-Poisson overdispersion. Leave-one-out cross-validation results indicate that the Bayesian predictive information criterion favored the D model, but a pairwise t -test indicated that the D model was not significantly better-fitting to singing-ground survey data than the S model. The H models are not preferable to the alternatives with normally distributed overdispersion. All models provided generally similar estimates of trend and annual indexes suggesting that, within this model set, choice of model will not lead to alternative conclusions regarding population change. However, as in Breeding Bird Survey analyses, we note a tendency for S model results to provide slightly more extreme estimates of trend relative to D models. We recommend use of the D model for future singing-ground survey analyses.

Eastern and Central United States and Canada↗
USGS2024

Effects of insecticide spray drift on arthropod prey resources of birds in grasslands in Minnesota

Soybean aphid ( Aphis glycines ) insecticides are used throughout the Upper Midwest and Great Plains regions of North America, including the farmland region of Minnesota, USA, to combat insect pests. These broad-spectrum, foliar spray insecticides have the potential to drift beyond target fields into nearby grassland cover where birds and other insectivores forage. Arthropods serve important roles in grassland ecology and are susceptible to mortality and sublethal effects from exposure to these pesticides. Our objective was to assess effects of soybean aphid insecticides on grassland arthropods, especially those that are important in grassland bird diets. We measured the abundance, consumable biomass, and family richness of insects and spiders in grasslands adjacent to soybean fields in an agricultural landscape. Soybean fields were treated with chlorpyrifos and lambda-cyhalothrin, which were the 2 most common foliar pesticides used to control soybean aphids in Minnesota. We compared measures at focal sites to samples collected at reference sites adjacent to corn fields not sprayed for aphids during 3 periods in mid-to-late summer: 1–3 days before spraying, 3–5 days post-spraying, and 19–21 days post-spraying. The abundance of arthropods in focal grasslands was lower 3–5 days after pesticide applications. Coleoptera family richness at focal sites was also lower than at reference sites 3–5 days after pesticide applications. These measures 19–21 days after application were similar to pre-spraying levels, indicating that arthropod populations rebounded during this period. Measures of consumable dry biomass, bird prey abundance, bird prey biomass, family richness of Araneae, family richness of Hemiptera, and family richness of Orthoptera were not different between focal and reference sites after spraying. Our results reveal that reductions in arthropod food abundance for grassland birds are associated with pesticide applications up to 5 days after spraying. We suggest that natural resource managers factor proximity to row crop fields and susceptibility to pesticide drift into decisions about where to add grassland cover to landscapes.

Minnesota↗
USGS1989

Annual survival rates of breeding adult roseate terns

Analyses of the capture-recapture data on 910 individual Roseate Terns ( Sterna dougallii ) trapped from 1978-1987 as breeding adults on nests on Falkner Island, Connecticut, estimate the average annual minimum adult survival rate to be 0.74-0.75. There was weak evidence of year-to-year variation in annual survival rates during the study period. The Jolly-Seber models used to estimate survival rates also generated estimates of population size and capture probabilities. To determine the relative importance of adult mortality and permanent emigration in contributing to the estimated annual loss of one-fourth of the breeding population will require further study of intercolony movement between all the major colony sites. Assuming that the loss of birds from the Falkner Island colony site is due mostly to mortality rather than permanent emigration, and that the survival rate of this breeding population is typical of the entire North Atlantic breeding population, then the survival rate of this endangered species is low in comparison to the survival rates of several other marine bird species in the orders Procellariiformes, Pelecaniformes, and Charadriiformes.

The Auk↗