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At least 181 records · Page 10Linked to original sources
USGS1988

Nutritional values of waterfowl foods

wetland habitats throughout their annual cycles. Survival, reproduction, and growth are dependent on the availability of foods that meet nutritional requirements for recurring biological events. These requirements occur among a wide variety of environmental conditions that also influence nutritional demands. Recent work on nesting waterfowl has identified the female’s general nutrient needs for egg laying and incubation. Far less is known about nutritional requirements for molt and other portions of the life cycle, particularly those during the nonbreeding season. Although information on specific requirements for amino acids and micronutrients of wild birds is meager, the available information on waterfowl requirements can be used to develop waterfowl management strategies. For example, nutrient content of foods, nutritional requirements of waterfowl, and the cues waterfowl use in locating and selecting foods are all kinds of information that managers need to encourage use of habitats by feeding waterfowl. Waterfowl nutritional needs during the annual cycle and the nutritional values of natural foods and crops will be discussed below.

Fish and Wildlife Leaflet↗
USGS2010

Unifying quantitative life-history theory and field endocrinology to assess prudent parenthood in a long-lived seabird

Question: Can field measurements of stress hormones help us to assess the prudent parent hypothesis in a long-lived seabird? Organism: Black-legged kittiwake, Rissa tridactyla . Location: Duck and Gull Islands, Cook Inlet, Alaska, USA. Methods: We examined the statistical relationship between the stress hormone corticosterone and mortality in black-legged kittiwakes. We built a demographic model of the kittiwake life cycle to determine whether the mortality rates associated with persisting in a breeding attempt despite high corticosterone caused the birds to sacrifice more lifetime reproductive output than they gain from one year’s breeding. Results: The probability of apparent mortality increased with corticosterone, suggesting some birds incurred increased mortality risk for the sake of breeding. For Duck Island (low reproductive success), it appears birds sacrificed more lifetime reproductive success than a prudent parent would. On Gull Island, it appears most but possibly not all birds were behaving in ways consistent with theory, although definitive statements require larger samples of highly stressed birds.

Alaska↗
USGS1958

Growth and development of the king rail

Growth and development of the King Rail ( Rallus elegans ) from hatching to first flight were studied by observations and measurements of captive birds and by observations of natural nests in the field. This is the fourth in a series of reports on the life history of the King Rail (Meanley 1953, 1956, and 1957). Information in this paper is intended to supplement the data of Bent (1925) on growth and development and the description of juvenal plumage given by Friedmann (1941).

The Auk↗
USGS2020

Bug flows: Don’t count your midges until they hatch

Usually when people hear about a “bug problem” it’s due to an undesirable overabundance of insects (think plague of locusts). In the Colorado River in Grand Canyon, however, we are faced with the opposite predicament: the river is essentially devoid of bugs. Aquatic insects are a fundamental component of a healthy river ecosystem. Most aquatic insects spend their juvenile life stages (egg, larva, pupa) in the river and their winged adult life stage flying along the riparian corridor. Throughout these metamorphoses one thing is for certain: aquatic insects are prey for fish, birds, bats, lizards, and even other invertebrates. In Grand Canyon, food web studies conducted by the US Geological Survey (USGS) have demonstrated that populations of both native and sport fish are food limited (Cross et al. 2013, Kennedy et al. 2013). In other words, fish in Grand Canyon are consistently facing a calorie deficit. Indeed, the US Fish and Wildlife Service has cited the inadequate and unreliable food supply as the single greatest problem facing endangered Humpback Chub populations in the Grand Canyon (USFWS 2019).

Boatman's Quarterly Review↗
USGS2024

Body mass changes of dabbling and diving ducks wintering in California

Bird body mass is often used as an index of body condition and fluctuates throughout the year in response to environmental conditions and avian life-history events. We examined the body mass of 59,572 ducks representing 13 species (7 dabbling duck species and 6 diving duck species) harvested within the 3 regions of the Central Valley in California, USA (Sacramento Valley, Suisun Marsh, San Joaquin Valley). Data collection occurred in winter during 5 hunting seasons (2014–2015, 2015–2016, 2017–2018, 2018–2019, 2019–2020). For all species, age, and sex classes, the body mass of dabbling ducks varied temporally and was lowest at the end of the hunting season in late January, declining from the beginning of the hunting season in mid-October (northern pintail [ Anas acuta ]: −11.4% to −20.4%; northern shoveler [ Spatula clypeata ]: −3.5% to −17.3%; cinnamon teal [ Anas cyanoptera ]: −5.0% to −17.1%; American wigeon [ Mareca americana ]: −6.9% to −12.2%; American green-winged teal [ Anas carolinensis ]: −5.9% to −11.9%; mallard [ Anas platyrhynchos ]: −1.8% to −9.6%; gadwall [ Mareca strepera ]: −2.2% to −8.4%). As expected, adults (after hatch-year) were heavier than immature (hatch-year) birds (within males: 0.6–8.6%; within females: 0.1–6.6%) and males were heavier than females (within adults: 3.1–38.6%; within immatures: 5.4–33.5%) at the end of the hunting season in all species. Within dabbling duck species, body masses did not differ among regions at the beginning of the hunting season but were heavier in the Sacramento Valley (0.5–14.4%) than other areas by the end of the hunting season. In contrast, body masses of diving ducks did not vary substantially during the hunting season or among regions. Diving ducks demonstrated inconsistent changes in mass from the beginning to the end of the season (lesser scaup [ Aythya affinis ]: 3.4% to 12.3%; canvasback [ Aythya valisineria ]: 5.1% to 6.1%; bufflehead [ Bucephala albeola ]: −3.2% to 1.6%; ring-necked duck [ Aythya collaris ]: −4.9% to 2.6%; common goldeneye [ Bucephala clangula ]: −3.2% to −2.4%; ruddy duck [ Oxyura jamaicensis ]: −16.5% to 5.5%). The substantial temporal and spatial differences in dabbling duck body masses suggest that habitat quality (as measured by caloric value of the available food) or quantity may decline during winter and varies regionally within California's Central Valley.

California↗
USGS2008

Mercury in precipitation in Indiana, January 2004–December 2005

Mercury in precipitation was monitored during 2004–2005 at five locations in Indiana as part of the National Atmospheric Deposition Program–Mercury Deposition Network (NADP–MDN). Monitoring stations were operated at Roush Lake near Huntington, Clifty Falls State Park near Madison, Fort Harrison State Park near Indianapolis, Monroe County Regional Airport near Bloomington, and Indiana Dunes National Lakeshore near Porter. At these monitoring stations, precipitation amounts were measured continuously and weekly samples were collected for analysis of mercury by methods achieving detection limits as low as 0.05 ng/L (nanograms per liter). Wet deposition was computed as the product of mercury concentration and precipitation. The data were analyzed for seasonal patterns, temporal trends, and geographic differences. In the 2 years, 520 weekly samples were collected at the 5 monitoring stations and 448 of these samples had sufficient precipitation to compute mercury wet deposition. The 2-year mean mercury concentration at the five monitoring stations (normalized to the sample volume) was 10.6 ng/L. As a reference for comparison, the total mercury concentration in 41 percent of the samples analyzed was greater than the statewide Indiana water-quality standard for mercury (12 ng/L, protecting aquatic life) and 99 percent of the concentrations exceeded the most conservative Indiana water-quality criterion (1.3 ng/L, protecting wild mammals and birds). The normalized annual mercury concentration at Clifty Falls in 2004 was the fourth highest in the NADP–MDN in eastern North America that year. In 2005, the mercury concentrations at Clifty Falls and Indiana Dunes were the ninth highest in the NADP–MDN in eastern North America. At the five monitoring stations during the study period, the mean weekly total mercury deposition was 0.208 µg/m 2 (micrograms per square meter) and mean annual total mercury deposition was 10.8 µg/m 2 . The annual mercury deposition at Clifty Falls in 2004 and 2005 was in the top 25 percent of the NADP–MDN stations in eastern North America. Mercury concentrations and deposition varied at the five monitoring stations during 2004–2005. Mercury concentrations in wet-deposition samples ranged from 1.2 to 116.6 ng/L and weekly mercury deposition ranged from 0.002 to 1.74 µg/m 2 . Data from weekly samples exhibited seasonal patterns. During April through September, total mercury concentrations and deposition were higher than the median for all samples. Annual precipitation at four of the five monitoring stations was within 10 percent of normal both years, with the exception of Indiana Dunes, where precipitation was 23 percent below normal in 2005. Episodes of high mercury deposition, which were the top 10 percent of weekly mercury deposition at the five monitoring stations, contributed 39 percent of all mercury deposition during 2004–2005. Mercury deposition more than 1.04 µg/m 2 (5 times the mean weekly deposition) was recorded for 12 samples. These episodes of highest mercury deposition were recorded at all five monitoring stations, but the most (7 of 12) were at Clifty Falls and contributed 34.4 percent of the total deposition at that station during 2004–2005. Weekly samples with high mercury deposition may help to explain the differences in annual mercury deposition among the five monitoring stations in Indiana. A statistical evaluation of the monitoring data for 2001–2005 indicated several statistically significant temporal trends. A statewide (5-station) decrease (p = 0.007) in mercury deposition and a statewide decrease (p = 0.059) in mercury concentration were shown. Decreases in mercury deposition (p = 0.061 and p = 0.083) were observed at Roush Lake and Bloomington. A statistically significant trend was not observed for precipitation at the five monitoring stations during this 5-year period. A potential explanation for part of the statewide decrease in mercury concentration and mercury deposition was a 28 percent decrease in the total estimated annual mercury emissions in Indiana between 2002 and 2005. Mercury deposition statistically was correlated most closely to precipitation in the 448 samples, 2004–2005, and this relation was demonstrated by statewide maps of annual precipitation and annual mercury deposition based on precipitation data from 127 National Weather Service Cooperative Observer Program stations. However, one area in southeastern Indiana in the vicinity of Clifty Falls exhibited high mercury deposition that might be related more to mercury concentration than to precipitation. This is because areas with the same range of precipitation as southeastern Indiana were mapped with less mercury deposition. Other data demonstrate a geographic difference for mercury in precipitation in the vicinity of the Clifty Falls monitoring station. The weekly mercury concentrations at Clifty Falls were statistically higher than concentrations at Roush Lake, Fort Harrison, and Bloomington. Clifty Falls data ranked highest among the five monitoring stations for mercury concentration and mercury deposition, 2004–2005, and in the previous 3 years. Episodes of high mercury deposition were recorded most often at Clifty Falls in 2004–2005 and in the previous 3 years. Statistical trends in mercury concentration or mercury deposition were not observed for the Clifty Falls data. A potential explanation for this geographic difference is that annual mercury emissions from sources in the vicinity of Clifty Falls were higher than those at the other stations. Other factors may help explain the differences in total mercury concentrations, such as the types of mercury emissions, mercury transport from stationary sources outside Indiana, and meteorological conditions. Additional data are needed to assign a localized or regional boundary to the area affected by high deposition of mercury near Clifty Falls.

Indiana↗
USGS2002

Marine predator surveys in Glacier Bay National Park and Preserve

Since 1999, vessel based surveys to estimate species composition, distribution and relative abundance of marine birds and mammals have been conducted along coastal and pelagic (offshore) transects in Glacier Bay, Alaska. Surveys have been conducted during winter (November-March) and summer (June). This annual report presents the results of those surveys conducted in March and June of 2001. Following completion of surveys in 2002 we will provide a final report of the results of all surveys conducted between 1999 and 2002. Glacier Bay supports diverse and abundant assemblages of marine birds and mammals. In 2001 we identified 58 species of bird, 7 species of marine mammal, and 6 species of terrestrial mammal on transects sampled during winter and summer. Of course all species are not equally abundant. Among all taxa, in both seasons, sea ducks were the numerically dominant group. In their roles as consumers and because of their generally large size, marine mammals are also likely important in the consumption of energy produced in the Glacier Bay ecosystem. Most common and abundant marine birds and mammals can be placed in either a fish based (e.g. alcids and pinnipeds), or a benthic invertebrate (e.g. sea ducks and sea otters) based food web. Distinct differences in the species composition and abundance of marine birds were observed between winter and summer surveys. Winter marine bird assemblages were dominated numerically (> 11,000; 65% of all birds) by a relatively few species of sea ducks (scoters, goldeneye, Bufflehead, Harlequin and Long-tailed ducks). The sea ducks were distributed almost exclusively along near shore habitats. The prevalence of sea ducks during the March surveys indicates the importance of Glacier Bay as a wintering area for this poorly understood group of animals that occupy a high trophic position in a principally benthic invertebrate (mussel and clam) food web. Marine mammal assemblages were generally consistent between seasons, although Humpback and Killer whales were not observed in winter 2001. Summer marine bird assemblages remained numerically dominated by sea ducks, but species composition shifted between the goldeneye whose density was 44/m 2 in winter to < 0.2/m 2 in summer, to scoters, whose density was 29/m 2 in winter to > 60/m 2 in summer. Large increases in Black-legged kittiwake, murrelet (Marbled and Kittlitz’s) and Common merganser densities were detected during summer surveys. Seasonal differences in abundance of species likely reflected differences in life history attributes (e.g. reproductive biology, foraging ecology) among species. Because of differences observed in species composition between the winter and summer, it is apparent that a single annual survey cannot accurately describe the populations of marine birds and mammals that occur in Glacier Bay. Preliminary analysis further suggests that interpretations of data resulting from this type of survey may depend to a large extent on the individual species. Because species exhibit differences in behavior, morphology, coloration, and distribution, accuracy and precision of abundance estimates likely vary among species. Confidence in survey results should be evaluated in consideration of life history and detection probabilities at the species level. However, survey results likely provide reasonable estimates of species composition and relative abundance, as well as accurate abundance estimates for those species whose detection closely approximates one.

Alaska↗
USGS2013

Demographic variation, reintroduction, and persistence of an island duck ( Anas laysanensis )

Population variation in life history can be important for predicting successful establishment and persistence of reintroduced populations of endangered species. The Laysan duck (Anas laysanensis) is an endangered bird native to the Hawaiian Archipelago that was extirpated from most islands after the introduction of mammalian predators. Laysan ducks were restricted to a single remote island, Laysan Island (4.1 km 2 ), for nearly 150 years. Since the species is not known to disperse between distant Hawaiian Islands today, 42 wild birds from Laysan Island were translocated to another mammalian predator-free low-lying atoll (Midway Atoll; 6.0 km 2 ) to reduce extinction risk. We explored how variation in demography influences establishment and longer-term retention of genetic diversity (rare alleles) for reintroductions of this species. We observed dramatic differences in population growth between the source (λ = 1.18) and reintroduced (λ = 3.28) population. The number of eggs hatched at Midway Atoll was greater than at Laysan Island, however, we found no difference in hatching success (proportion of clutch hatched) between populations. Adult females produced 3 times as many fledglings per breeding year on Midway Atoll compared to Laysan Island. We estimated population abundance of both populations until 2010 and applied a Gompertz model with a Bayesian approach to infer density dependence, process variation, observation error, and carrying capacity for the Laysan Island and Midway Atoll populations. The carrying capacity from the Gompertz model for Midway Atoll (K = 883 ± 210 SD) was estimated to be greater than that of Laysan Island (K = 598 ± 76 SD). Translocations with small numbers of founders and no immigration can create population bottlenecks, leading to loss of genetic variation over time, and potentially reducing the reintroduced population's viability or its potential to serve as a source for future translocations. Therefore, we also assessed the probability of retaining rare alleles in an isolated reintroduced Laysan duck population using life history parameters observed from the Laysan Island and Midway Atoll populations; we concluded that additional founders are needed under scenarios using demographic estimates from both Laysan Island and Midway Atoll to retain either 90% or 95% of source population genetic diversity.

Laysan Island;Midway Atoll↗
USGS2023

Critical review of the phytohemagglutinin assay for assessing amphibian immunity

Infectious diseases are a major driver of the global amphibian decline. In addition, many factors, including genetics, stress, pollution, and climate change can influence the response to pathogens. Therefore, it is important to be able to evaluate amphibian immunity in the laboratory and in the field. The phytohemagglutinin (PHA) assay is an inexpensive and relatively non-invasive tool that has been used extensively to assess immunocompetence, especially in birds, and more recently in amphibians. However, there is substantial variation in experimental methodology among amphibian PHA studies in terms of species and life stages, PHA doses and injection sites, and use of experimental controls. Here, we compile and compare all known PHA studies in amphibians to identify knowledge gaps and develop best practices for future work. We found that research has only been conducted on a limited number of species, which may not reflect the diversity of amphibians. There is also a lack of validation studies in most species, so that doses and timing of PHA injection and subsequent swelling measurements may not effectively evaluate immunocompetence. Based on these and other findings, we put forward a set of recommendations to make future PHA studies more consistent and improve the ability to utilize this assay in wild populations, where immune surveillance is greatly needed.

Conservation Physiology↗
USGS2002

Role of selenium toxicity and oxidative stress in aquatic birds

Adverse effects of selenium (Se) in wild aquatic birds have been documented as a consequence of pollution of the aquatic environment by subsurface agricultural drainwater and other sources. These effects include mortality, impaired reproduction with teratogenesis, reduced growth, histopathological lesions and alterations in hepatic glutathione metabolism. A review is provided, relating adverse biological effects of Se in aquatic birds to altered glutathione metabolism and oxidative stress. Laboratory studies, mainly with an organic form of Se, selenomethionine, have revealed oxidative stress in different stages of the mallard (Anas platyrhynchos) life cycle. As dietary and tissue concentrations of Se increase, increases in plasma and hepatic GSH peroxidase activities occur, followed by dose-dependent increases in the ratio of hepatic oxidized to reduced glutathione (GSSG:GSH) and ultimately hepatic lipid peroxidation measured as an increase in thiobarbituric acid reactive substances (TBARS). One or more of these oxidative effects were associated with teratogenesis (4.6 ppm wet weight Se in eggs), reduced growth in ducklings (15 ppm Se in liver), diminished immune function (5 ppm Se in liver) and histopathological lesions (29 ppm Se in liver) in adults. Manifestations of Serelated effects on glutathione metabolism were also apparent in field studies in seven species of aquatic birds. Reduced growth and possibly immune function but increased liver:body weight and hepatic GSSG:GSH ratios were apparent in American avocet (Recurvirostra americana) hatchlings from eggs containing 9 ppm Se. In blacknecked stilts (Himantopus mexicanus), which contained somewhat lower Se concentrations, a decrease in hepatic GSH was apparent with few other effects. In adult American coots (Fulica americana), signs of Se toxicosis included emaciation, abnormal feather loss and histopathological lesions. Mean liver concentrations of 28 ppm Se (ww) in the coots were associated with elevated hepatic GSH peroxidase, depletion of hepatic protein bound thiols and total thiols, but a small increase in GSH. Diving ducks in the San Francisco Bay area exhibited a positive correlation between hepatic Se concentration and GSH peroxidase activity (r=0.63, P<0.05), but a negative correlation between hepatic Se and GSH concentration (r=0.740, P<0.05). In willets (Catoptrophorus semipalmatus) from the San Diego area, positive correlations occurred between hepatic Se concentration and GSSG (r=0.70, P<0.001), GSSG:GSH ratio, and TBARS. In emperor geese (Chen canagica) from western Alaska, blood levels of up to 9.4 ppm occurred and were associated with increased plasma GSH peroxidase activity (r=0.62, P<0.001), but with decreased plasma GSSG reductase activity. When evaluating Se toxicity, interactive nutritional factors, including other elements and dietary protein, should also be taken into consideration. Further studies are needed to examine the relationship between different forms of environmentally occurring selenium, arsenic and mercury on reproduction, hepatotoxicity and immune function of aquatic birds. Further selenium nutritional interaction studies may also help to illucidate the mechanism of selenium induced teratogenesis, by optimizing GSH and other antioxidant defense mechanisms in a manner that would stabilize or raise the cell's threshold for susceptibility to toxic attack from excess selenium. It is concluded that Se-related manifestations of oxidative stress may serve as useful bioindicators of Se exposure and toxicity in wild aquatic birds.

Aquatic Toxicology↗
USGS2009

Peptide synthesis in early earth hydrothermal systems

We report here results from experiments and thermodynamic calculations that demonstrate a rapid, temperature-enhanced synthesis of oligopeptides from the condensation of aqueous glycine. Experiments were conducted in custom-made hydrothermal reactors, and organic compounds were characterized with ultraviolet-visible procedures. A comparison of peptide yields at 260??C with those obtained at more moderate temperatures (160??C) gives evidence of a significant (13 kJ ?? mol -1 ) exergonic shift. In contrast to previous hydrothermal studies, we demonstrate that peptide synthesis is favored in hydrothermal fluids and that rates of peptide hydrolysis are controlled by the stability of the parent amino acid, with a critical dependence on reactor surface composition. From our study, we predict that rapid recycling of product peptides from cool into near-supercritical fluids in mid-ocean ridge hydrothermal systems will enhance peptide chain elongation. It is anticipated that the abundant hydrothermal systems on early Earth could have provided a substantial source of biomolecules required for the origin of life. Astrobiology 9, 141-146. ?? 2009 Mary Ann Liebert, Inc. 2009.

Astrobiology↗
USGS1999

Mountain chickadee (Poecile gambeli)

The Mountain Chickadee (Poecile gambeli), a small, cavity-nesting songbird, is one of the most common birds of montane and coniferous forest from southern Arizona and Baja California north to British Columbia and the Yukon territory. This publication describes the life history of the Mountain Chickadee.

Report↗
USGS2002

Influence of hydrology on life-history parameters of common freshwater fishes from southern Florida

Fishes are essential to the successful functioning of wetland food webs in southern Florida through their roles as prey and predators. Any changes that reduce the population sizes, community composition, or availability of aquatic animals will affect all facets of the ecology of these wetlands. In particular, small and medium-size fishes are important food items for most wading bird species. For this reason, fishes have been recognized by the multi-agency groups responsible for guiding the Everglades restoration process as a key indicator group by which to measure restoration success. Despite the importance of fish for management, gaps in baseline knowledge remain. Basic demographic information, termed life-history parameters, is needed to make predictions about their resilience under alternative management scenarios. These parameters include growth rate, age at maturation, fecundity and life expectancy. However, basic life-history parameters remain to be characterized, even for abundant fish species. Adding to the challenge, life-history characteristics of important Everglades species are known to be plastic in response to environmental conditions and survivorship and recruitment schedules are certain to be influenced by variation in hydroperiod. We intend to study the effect of hydroperiod on recruitment, size/age structure, growth, and fecundity, which, in turn, determine fish population dynamics. At present, data on fish reproduction, age and growth, and other life history characteristics are confined to a few species from a limited area of long-hydroperiod marsh in central Shark River Slough. As we continue the analysis and synthesis of data from the long-term fish collections, life-history information will help explain patterns of fluctuations in the time series. Accurate life-history data are also very important in building credible simulation models like ATLSS. Without empirical life-history data from a range of environments, the model will be simplistic and inadequate.

Florida↗
USGS2014

Habitat prioritization across large landscapes, multiple seasons, and novel areas: an example using greater sage-grouse in Wyoming

Animal habitat selection is an important and expansive area of research in ecology. In particular, the study of habitat selection is critical in habitat prioritization efforts for species of conservation concern. Landscape planning for species is happening at ever-increasing extents because of the appreciation for the role of landscape-scale patterns in species persistence coupled to improved datasets for species and habitats, and the expanding and intensifying footprint of human land uses on the landscape. We present a large-scale collaborative effort to develop habitat selection models across large landscapes and multiple seasons for prioritizing habitat for a species of conservation concern. Greater sage-grouse ( Centrocercus urophasianus , hereafter sage-grouse) occur in western semi-arid landscapes in North America. Range-wide population declines of this species have been documented, and it is currently considered as “warranted but precluded” from listing under the United States Endangered Species Act. Wyoming is predicted to remain a stronghold for sage-grouse populations and contains approximately 37% of remaining birds. We compiled location data from 14 unique radiotelemetry studies (data collected 1994–2010) and habitat data from high-quality, biologically relevant, geographic information system (GIS) layers across Wyoming. We developed habitat selection models for greater sage-grouse across Wyoming for 3 distinct life stages: 1) nesting, 2) summer, and 3) winter. We developed patch and landscape models across 4 extents, producing statewide and regional (southwest, central, northeast) models for Wyoming. Habitat selection varied among regions and seasons, yet preferred habitat attributes generally matched the extensive literature on sage-grouse seasonal habitat requirements. Across seasons and regions, birds preferred areas with greater percentage sagebrush cover and avoided paved roads, agriculture, and forested areas. Birds consistently preferred areas with higher precipitation in the summer and avoided rugged terrain in the winter. Selection for sagebrush cover varied regionally with stronger selection in the Northeast region, likely because of limited availability, whereas avoidance of paved roads was fairly consistent across regions. We chose resource selection function (RSF) thresholds for each model set (seasonal × regional combination) that delineated important seasonal habitats for sage-grouse. Each model set showed good validation and discriminatory capabilities within study-site boundaries. We applied the nesting-season models to a novel area not included in model development. The percentage of independent nest locations that fell directly within identified important habitat was not overly impressive in the novel area (49%); however, including a 500-m buffer around important habitat captured 98% of independent nest locations within the novel area. We also used leks and associated peak male counts as a proxy for nesting habitat outside of the study sites used to develop the models. A 1.5-km buffer around the important nesting habitat boundaries included 77% of males counted at leks in Wyoming outside of the study sites. Data were not available to quantitatively test the performance of the summer and winter models outside our study sites. The collection of models presented here represents large-scale resource-management planning tools that are a significant advancement to previous tools in terms of spatial and temporal resolution.

Wyoming↗
USGS2021

A decision tool to identify population management strategies for common ravens and other avian predators

Some avian species have developed the capacity to leverage resource subsidies associated with human manipulated landscapes to increase population densities in habitats with naturally low carrying capacities. Elevated corvid densities and new territory establishment have led to an unsustainable increase in depredation pressure on sympatric native wildlife prey populations as well as in crop damage. Yet, subsidized predator removal programs aimed at reducing densities are likely most effective longer-term when conducted in tandem with subsidy control, habitat management, and robust assessment monitoring programs. We developed decision support software that leverages stage structured Lefkovitch population matrices to compare and identify treatment strategies that reduce subsidized avian predator densities most efficiently, in terms of limiting both cost and take levels. The StallPOPd (Version 4; available at https://doi.org/10.7298/sk2e-0c38.4) software enables managers to enter the area of their management stratum and the demographic properties (vital rates) of target bird population(s) of interest to evaluate strategies to decrease or curtail further population growth. Strategies explicitly include the reduction in fertility (i.e., eggs hatched) and/or the culling of hatchlings, non-breeders and/or breeders, but implicitly comprise reduction in survival or reproduction through subsidy denial. We illustrate the utilities of the software with examples using common ravens ( Corvus corax; ravens) in the Mojave Desert of California, USA. Unfortunately, the survival and reproduction effects of each unit of a particular subsidy in that system have remained elusive, though this is the priority of current research. Because the software leverages a life history representation that is known to characterize hundreds of wildlife species in addition to ravens, the work expands the suite of tools available to wildlife managers and agricultural industry specialists to abate bird damage and impacts on sensitive wildlife in habitats with persistent human subsidies.

Human-Wildlife Interactions↗
USGS2017

Use of North American Breeding Bird Survey data in avian conservation assessments

Conservation resources are limited, and prioritizing species based on their relative vulnerability and risk of extinction is a fundamental component of conservation planning. In North America, the conservation consortium Partners in Flight (PIF) has developed and implemented a data-driven species assessment process, at global and regional scales, based on quantitative vulnerability criteria. This species assessment process has formed the biological basis for PIF's continental and regional planning and has informed the ranking and legal listing of bird species for conservation protection by state, provincial, and national agencies in Canada, the U.S., and Mexico. Because of its long time series, extensive geographic and species coverage, standardized survey methods, and prompt availability of results, the North American Breeding Bird Survey (BBS) has been an invaluable source of data, allowing PIF to assign objective vulnerability scores calibrated across more than 460 landbird species. BBS data have been most valuable for assessing long-term population trends (PT score). PIF has also developed methods for estimating population size by extrapolating from BBS abundance indices, allowing the assignment of categorical population size (PS) scores for landbird species. At regional scales, BBS relative abundance indices have allowed PIF to assess the area importance (i.e. stewardship responsibility) of each Bird Conservation Region (BCR) for each species, using measures of both relative density and percent of total population in each BCR. Besides direct applicability to assessment scores, PIF has recently used BBS trend data to create new metrics of conservation urgency (e.g., ‘half-life'), as well as for setting population objectives for tracking progress toward meeting conservation goals. Future directions include integrating BBS data with other sources (e.g., eBird) to assess additional species and nonbreeding season measures, working closely with BBS coordinators to expand surveys into Mexico, and providing assessment scores at implementation-relevant scales, such as for migratory bird joint ventures.

The Condor↗
USGS2004

Species Conservation and Management: Case Studies

This edited volume is a collection of population and metapopulation models for a wide variety of species, including plants, invertebrates, fishes, amphibians, reptiles, birds, and mammals. Each chapter of the book describes the application of RAMAS GIS 4.0 to one species, with the aim of demonstrating how various life history characteristics of the species are incorporated into the model, and how the results of the model has been or can be used in conservation and management of the species. The book comes with a CD that includes a demo version of the program, and the data files for each species.

Book↗
USGS2002

Test for age-specificity in survival of the common tern

Much effort in life-history theory has been addressed to the dependence of life-history traits on age, especially the phenomenon of senescence and its evolution. Although senescent declines in survival are well documented in humans and in domestic and laboratory animals, evidence for their occurrence and importance in wild animal species remains limited and equivocal. Several recent papers have suggested that methodological issues may contribute to this problem, and have encouraged investigators to improve sampling designs and to analyse their data using recently developed approaches to modelling of capture-mark-recapture data. Here we report on a three-year, two-site, mark-recapture study of known-aged common terns (Sterna hirundo) in the north-eastern USA. The study was nested within a long-term ecological study in which large numbers of chicks had been banded in each year for > 25 years. We used a range of models to test the hypothesis of an influence of age on survival probability. We also tested for a possible influence of sex on survival. The cross-sectional design of the study (one year's parameter estimates) avoided the possible confounding of effects of age and time. The study was conducted at a time when one of the study sites was being colonized and numbers were increasing rapidly. We detected two-way movements between the sites and estimated movement probabilities in the year for which they could be modelled. We also obtained limited data on emigration from our study area to more distant sites. We found no evidence that survival depended on either sex or age, except that survival was lower among the youngest birds (ages 2-3 years). Despite the large number of birds included in the study (1599 known-aged birds, 2367 total), confidence limits on estimates of survival probability were wide, especially for the oldest age-classes, so that a slight decline in survival late in life could not have been detected. In addition, the cross-sectional design of this study meant that a decline in survival probability within individuals (actuarial senescence) could have been masked by heterogeneity in survival probability among individuals (mortality selection). This emphasizes the need for the development of modelling tools permitting separation of these two phenomena, valid under field conditions in which the recapture probabilities are less than one.

Book chapter↗