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At least 343 records · Page 19Linked to original sources
USGS2017

The role of the North American Breeding Bird Survey in conservation

The North American Breeding Bird Survey (BBS) was established in 1966 in response to a lack of quantitative data on changes in the populations of many bird species at a continental scale, especially songbirds. The BBS now provides the most reliable regional and continental trends and annual indices of abundance available for >500 bird species. This paper reviews some of the ways in which BBS data have contributed to bird conservation in North America over the past 50 yr, and highlights future program enhancement opportunities. BBS data have contributed to the listing of species under the Canadian Species at Risk Act and, in a few cases, have informed species assessments under the U.S. Endangered Species Act. By raising awareness of population changes, the BBS has helped to motivate bird conservation efforts through the creation of Partners in Flight. BBS data have been used to determine priority species and locations for conservation action at regional and national scales through Bird Conservation Region strategies and Joint Ventures. Data from the BBS have provided the quantitative foundation for North American State of the Birds reports, and have informed the public with regard to environmental health through multiple indicators, such as the Canadian Environmental Sustainability Indicators and the U.S. Environmental Protection Agency's Report on the Environment. BBS data have been analyzed with other data (e.g., environmental, land cover, and demographic) to evaluate potential drivers of population change, which have then informed conservation actions. In a few cases, BBS data have contributed to the evaluation of management actions, including informing the management of Mourning Doves ( Zenaida macroura ), Wood Ducks ( Aix sponsa ), and Golden Eagles ( Aquila chrysaetos ). Improving geographic coverage in northern Canada and in Mexico, improving the analytical approaches required to integrate data from other sources and to address variation in detectability, and completing the database, by adding historical bird data at each point count location and pinpointing the current point count locations would further enhance the survey's value.

Condor↗
USGS2017

Combined analysis of roadside and off-road breeding bird survey data to assess population change in Alaska

Management interest in North American birds has increasingly focused on species that breed in Alaska, USA, and Canada, where habitats are changing rapidly in response to climatic and anthropogenic factors. We used a series of hierarchical models to estimate rates of population change in 2 forested Bird Conservation Regions (BCRs) in Alaska based on data from the roadside North American Breeding Bird Survey (BBS) and the Alaska Landbird Monitoring Survey, which samples off-road areas on public resource lands. We estimated long-term (1993–2015) population trends for 84 bird species from the BBS and short-term (2003–2015) trends for 31 species from both surveys. Among the 84 species with long-term estimates, 11 had positive trends and 17 had negative trends in 1 or both BCRs; negative trends were primarily found among aerial insectivores and wetland-associated species, confirming range-wide negative continental trends for many of these birds. Three species with negative trends in the contiguous United States and southern Canada had positive trends in Alaska, suggesting different population dynamics at the northern edges of their ranges. Regional population trends within Alaska differed for several species, particularly those represented by different subspecies in the 2 BCRs, which are separated by rugged, glaciated mountain ranges. Analysis of the roadside and off-road data in a joint hierarchical model with shared parameters resulted in improved precision of trend estimates and suggested a roadside-related difference in underlying population trends for several species, particularly within the Northwestern Interior Forest BCR. The combined analysis highlights the importance of considering population structure, physiographic barriers, and spatial heterogeneity in habitat change when assessing patterns of population change across a landscape as broad as Alaska. Combined analysis of roadside and off-road survey data in a hierarchical framework may be particularly useful for evaluating patterns of population change in relatively undeveloped regions with sparse roadside BBS coverage.

Condor↗
USGS2017

Integrating Breeding Bird Survey and demographic data to estimate Wood Duck population size in the Atlantic Flyway

The U.S. Fish and Wildlife Service (USFWS) uses data from the North American Breeding Bird Survey (BBS) to assist in monitoring and management of some migratory birds. However, BBS analyses provide indices of population change rather than estimates of population size, precluding their use in developing abundance-based objectives and limiting applicability to harvest management. Wood Ducks ( Aix sponsa ) are important harvested birds in the Atlantic Flyway (AF) that are difficult to detect during aerial surveys because they prefer forested habitat. We integrated Wood Duck count data from a ground-plot survey in the northeastern U.S. with AF-wide BBS, banding, parts collection, and harvest data to derive estimates of population size for the AF. Overlapping results between the smaller-scale intensive ground-plot survey and the BBS in the northeastern U.S. provided a means for scaling BBS indices to the breeding population size estimates. We applied these scaling factors to BBS results for portions of the AF lacking intensive surveys. Banding data provided estimates of annual survival and harvest rates; the latter, when combined with parts-collection data, provided estimates of recruitment. We used the harvest data to estimate fall population size. Our estimates of breeding population size and variability from the integrated population model (N̄ = 0.99 million, SD = 0.04) were similar to estimates of breeding population size based solely on data from the AF ground-plot surveys and the BBS (N̄ = 1.01 million, SD = 0.04) from 1998 to 2015. Integrating BBS data with other data provided reliable population size estimates for Wood Ducks at a scale useful for harvest and habitat management in the AF, and allowed us to derive estimates of important demographic parameters (e.g., seasonal survival rates, sex ratio) that were not directly informed by data.

The Condor↗
USGS2018

Demographic rates of two southeastern populations of Painted Bunting, 2007–2015

Painted Buntings ( Passerina ciris ) have been declining in the southeastern United States since the 1970s. A recent demographic assessment highlighted the importance of estimating demographic parameters, which have received little attention to date. The dearth of information is troublesome because attempts to reverse declining trends require a better understanding of the relationship between habitat quality and age- and sex-specific survival and recruitment rates. We used capture–mark–recapture data collected from 2007 to 2015 on Bald Head Island (BHI) and at Hammocks Beach State Park (HBSP) in North Carolina, USA, to estimate local age- and sex-specific annual survival rates and local population size and recruitment rates using programs MARK and LOLASURVIV. Juveniles had lower local survival rates than adults (HBSP: 0.28 ± 0.14 vs. 0.67 ± 0.06; BHI: 0.28 ± 0.04 vs. 0.57 ± 0.02). Local annual survival rates for males on BHI (0.50 ± 0.03) were lower than those for females (0.57 ± 0.02). Age-specific differences were consistent with known differential age-dependent survival skills, and sex-specific differences were consistent with the potential influence of sexual dichromism. Conservative estimates of population size on BHI averaged 101 juveniles and 263 adults annually. Annual in situ reproductive recruitment averaged 28 individuals plus an additional 120 new immigrants, indicating successful reproduction and connectivity with neighboring coastal populations. Local adult survival estimates from our 2 North Carolinian study populations were similar to high-end estimates from across the eastern and western range of the species (∼0.60). Finite observed population growth rate estimates between the BHI population (λ = 1.10) and a South Carolinian population (λ = 0.87) underscore the potential role of differential habitat quality and the importance of information from multiple sites, including nonbreeding grounds, for proper inferences about the status of the species. Reported vital rates provide a stronger foundation on which to base habitat quality as assessed with demographic parameters and to guide Painted Bunting conservation regionally.

North Carolina↗
USGS2018

Opportunistically collected data reveal habitat selection by migrating Whooping Cranes in the U.S. Northern Plains

The Whooping Crane ( Grus americana ) is a federally endangered species in the United States and Canada that relies on wetland, grassland, and cropland habitat during its long migration between wintering grounds in coastal Texas, USA, and breeding sites in Alberta and Northwest Territories, Canada. We combined opportunistic Whooping Crane sightings with landscape data to identify correlates of Whooping Crane occurrence along the migration corridor in North Dakota and South Dakota, USA. Whooping Cranes selected landscapes characterized by diverse wetland communities and upland foraging opportunities. Model performance substantially improved when variables related to detection were included, emphasizing the importance of accounting for biases associated with detection and reporting of birds in opportunistic datasets. We created a predictive map showing relative probability of occurrence across the study region by applying our model to GIS data layers; validation using independent, unbiased locations from birds equipped with platform transmitting terminals indicated that our final model adequately predicted habitat use by migrant Whooping Cranes. The probability map demonstrated that existing conservation efforts have protected much top-tier Whooping Crane habitat, especially in the portions of North Dakota and South Dakota that lie east of the Missouri River. Our results can support species recovery by informing prioritization for acquisition and restoration of landscapes that provide safe roosting and foraging habitats. Our results can also guide the siting of structures such as wind towers and electrical transmission and distribution lines, which pose a strike and mortality risk to migrating Whooping Cranes.

North Dakota, South Dakota↗
USGS2018

Response of beach-nesting American Oystercatchers to off-road vehicles: An experimental approach reveals physiological nuances and decreased nest attendance

Shorebird populations face increasing challenges as rising sea levels and growing human populations constrain their breeding habitats. On recreational beaches, the nesting season often coincides with a season of high visitor use, increasing the potential for conflict, which may negatively influence beach-nesting shorebird species. We designed a field experiment to study the responses of nesting American Oystercatchers ( Haematopus palliatus ) to off-road passenger vehicles (ORVs) at Cape Hatteras and Cape Lookout National Seashores in North Carolina, USA. We used continuous video and heart rate recordings to assess changes in the behavior and physiology of incubating oystercatchers. We conducted driving experiments affecting 7 nesting pairs in 2014 and 19 nesting pairs in 2015, between April and July of each year. Experimental treatments were repeated throughout the incubation period for each nest. Although responses were highly variable within and among pairs, paired randomized permutation tests indicated that, overall, oystercatcher pairs spent a greater proportion of time with their heads up and exhibited slower heart rates during driving treatments. Pairs also left their nests more frequently and attended their nests for a lower proportion of time during driving treatments, although these responses diminished over time. Higher nest attendance and lower departure rates late in incubation may have reflected a stronger attachment to nests closer to hatching or habituation to the driving treatment, although individuals continued to exhibit physiological responses to passing vehicles throughout incubation. Beach-nesting birds may benefit from reduced vehicle traffic at their nesting sites, allowing parents to spend more time attending the nest and less time on defensive behaviors.

North Carolina↗
USGS2018

Spatial patterns in occupancy and reproduction of Golden Eagles during drought: Prospects for conservation in changing environments

We used a broad-scale sampling design to investigate spatial patterns in occupancy and breeding success of territorial pairs of Golden Eagles ( Aquila chrysaetos ) in the Diablo Range, California, USA, during a period of exceptional drought (2014–2016). We surveyed 138 randomly selected sample sites over 4 occasions each year and identified 199 pairs of eagles, 100 of which were detected in focal sample sites. We then used dynamic multistate modeling to identify relationships between site occupancy and reproduction of Golden Eagles relative to spatial variability in landscape composition and drought conditions. We observed little variability among years in site occupancy (3-yr mean = 0.74), but the estimated annual probability of successful reproduction was relatively low during the study period and declined from 0.39 (± 0.08 SE) to 0.18 (± 0.07 SE). Probabilities of site occupancy and reproduction were substantially greater at sample sites that were occupied by successful breeders in the previous year, indicating the presence of sites that were consistently used by successfully reproducing eagles. We found strong evidence for nonrandom spatial distribution in both occupancy and reproduction: Sites with the greatest potential for occupancy were characterized by rugged terrain conditions with intermediate amounts of grassland interspersed with patches of oak woodland and coniferous forest, whereas successful reproduction was most strongly associated with the amount of precipitation that a site received during the nesting period. Our findings highlight the contribution of consistently occupied and productive breeding sites to overall productivity of the local breeding population, and show that both occupancy and reproduction at these sites were maintained even during a period of exceptional drought. Our approach to quantifying and mapping site quality should be especially useful for the spatial prioritization of compensation measures intended to help offset the impacts of increasing human land use and development on Golden Eagles and their habitats.

California↗
USGS2018

Research and management priorities for Hawaiian forest birds

Hawai‘i's forest birds face a number of conservation challenges that, if unaddressed, will likely lead to the extinction of multiple species in the coming decades. Threats include habitat loss, invasive plants, non-native predators, and introduced diseases. Climate change is predicted to increase the geographic extent and intensity of these threats, adding urgency to implementation of tractable conservation strategies. We present a set of actionable research and management approaches, identified by conservation practitioners in Hawai'i, that will be critical for the conservation of Hawaiian forest birds in the coming years. We also summarize recent progress on these conservation priorities. The threats facing Hawai‘i's forest birds are not unique to Hawai‘i, and successful conservation strategies developed in Hawai‘i can serve as a model for other imperiled communities around the world, especially on islands.

Hawai‘i↗
USGS2018

Evaluating time-removal models for estimating availability of boreal birds during point count surveys: Sample size requirements and model complexity

We used conventional and finite mixture removal models with and without time-varying covariates to evaluate availability given presence for 152 bird species using data from point counts in boreal North America. We found that the choice of model had an impact on the estimability of unknown model parameters and affected the bias and variance of corrected counts. Finite mixture models provided better fit than conventional removal models and better adjusted for count duration. However, reliably estimating parameters and minimizing variance using mixture models required at least 200–1,000 detections. Mixture models with time-varying proportions of infrequent singers were best supported across species, indicating that accounting for date- and time-related heterogeneity is important when combining data across studies over large spatial scales, multiple sampling time frames, or variable survey protocols. Our flexible and continuous time-removal modeling framework can be used to account for such heterogeneity through the incorporation of easily obtainable covariates, such as methods, date, time, and location. Accounting for availability bias in bird surveys allows for better integration of disparate studies at large spatial scales and better adjustment of local, regional, and continental population size estimates.

Condor↗
USGS2018

A new approach to automated incubation recess detection using temperature loggers

Nest attendance during incubation is an important facet of avian nesting behavior, and understanding the number, timing, and duration of incubation recesses can improve our understanding of the factors determining avian reproductive success. Temperature loggers are a low-cost, noninvasive method for studying nest attendance, but processing and interpreting the data present logistical challenges for investigators. We developed an accurate automated method for processing data from temperature loggers to identify incubation recesses. This automated method combines absolute changes in nest temperature over time and changes relative to daily nest-specific variation in temperature to identify incubation recesses. We validated this method through comparison with recesses observed during continuous infrared video monitoring of 3 Mallard ( Anas platyrhynchos ) and 7 Gadwall ( Mareca strepera ) nests in northern California, USA. Of 116 recesses observed on camera, we detected 102 (88%) with automated recess detection. After excluding 7 recesses in which nest temperature did not decrease during the recess, and which would therefore have been undetectable without ancillary data, we detected 102 of 109 (94%) recesses with automated recess detection. The time lag in detecting a hen's departure from her nest (i.e. when the recess had begun) was influenced by ambient temperature, although detection of the recess itself was not. The lag in detecting the start of a recess was (mean ± SD) 6.9 ± 2.7 min when ambient temperatures were below 30°C, and 13.7 ± 3.2 min at temperatures above 30°C. The lag in detecting the end of a recess was 1.7 ± 3.2 min and was not affected by ambient temperature. Recesses observed on camera were slightly longer (178.3 ± 122.2 min) than those estimated with automated recess detection (158.7 ± 93.1 min), with the time lag in detecting the start of a recess under warm ambient temperatures contributing the most to the difference. These results demonstrate the accuracy of the automated method that we have developed for identifying the timing and duration of incubation recesses using nest temperature data. This method was developed using data from dabbling ducks but is readily adaptable to other avian taxa with appropriate changes in user-defined criteria for identifying incubation recesses.

The Condor↗
USGS2018

Interisland genetic structure of two endangered Hawaiian waterbirds: The Hawaiian Coot and Hawaiian Gallinule

Most of Hawaii's endemic avifauna are species of conservation concern. Some of Hawaii's endangered waterbirds, however, have increased in number as a result of intensive management of wetlands. To inform these conservation efforts, we examined interisland genetic structure and gene flow within 2 Hawaiian endemic waterbirds, the Hawaiian Coot ( Fulica alai ) and the Hawaiian subspecies of the Common Gallinule ( Gallinula galeata sandvicensis ), using microsatellite and mitochondrial loci. Hawaiian Coots and Hawaiian Gallinules occupy coastal wetlands and exhibit similar life history characteristics and generation times, although they may differ in dispersal propensity. Mark–resight data for Hawaiian Coot indicate interisland movements, whereas Hawaiian Gallinules are sedentary. Genetic diversity is partitioned across the landscape differently for Hawaiian Coots and Hawaiian Gallinules; patterns of variation are likely influenced by behavioral and ecological mechanisms. Hawaiian Coots exhibit low levels of structure at microsatellite loci ( F ST = 0.029) and high levels of gene flow among islands. Conversely, Hawaiian Gallinules are highly structured across marker types (microsatellite F ST = 0.205, mtDNA control region F ST = 0.370, mtDNA ND2 F ST = 0.087), with restricted recent gene flow. Patterns of gene flow have changed after the population declines in the early to mid-1900s. Gene flow estimates indicate historical dispersal from Kauai to Oahu in both species, while recent estimates show individual Hawaiian Coots dispersing from Oahu and restricted gene flow between islands for the Hawaiian Gallinule. Changes in gene flow through time suggest that patterns of dispersal may be an artifact of the availability of habitat, which may be indirectly associated with the synergistic influences of population density and wetland quality. Despite recent population size increases for both species, continued threats to Hawaiian waterbirds (i.e. nonnative mammalian predators and invasive plants, avian disease, altered hydrology, and saltwater inundation of freshwater wetlands) will likely require continued active management to maintain viable populations.

Hawaii↗
USGS1944

Food habits of blue grouse

The food habits of Blue Grouse vary from a simple winter diet that is made up predominantly of coniferous needles to a complex diet during the summer months, characterized by great variety of foods including green leaves, fruits and seeds, flowers, animal matter and coniferous needles. The spring and fall, which represent the transition periods between these two, are characterized by feeding habits that are generally intermediate. The diets of the two species of Blue Grouse, Dendrugapus obscurus and Dendragapus juliginosus, are quite similar as far as major types of food are concerned, but they differ considerably in the species that are taken. Such differences reflect differences in the vegetation within the ecologic and geographic ranges occupied by the two species.

Condor↗
USGS1966

Spermatogenesis in bald eagles experimentally fed a diet containing DDT

When Bald Eagles were fed DDT in the diet at the level of 10 ppm (dry weight basis) for periods of 60 and 120 days, there was no interference with spermatogenic activity. Degenerative testicular changes were produced only by levels of DDT that produced abnormal neurological signs and usually resulted in death. Histological examination of these testes indicates that Bald Eagles have a seasonal testicular cycle similar to that reported for many other birds of the Northern Hemisphere.

Condor↗
USGS1973

Distribution of two western clapper rail races as determined by responses to taped calls

During 1969 and 1970, surveys of the endangered Yuma Clapper Rail were conducted using taped calls to elicit responses from the birds. During the two summers, more than 158 Yuma clappers were located in cattailtule marshes along the Colorado River south of Needles, California, to the International Boundary, a distance of about 240 miles. Clappers (probably of the same race) were also found in estuarian marshes of the Colorado River Delta of Mexico; in the Salton Sea; in two freshwater marsh areas near Phoenix, Arizona; and in two freshwater marshes adjacent to the lower Gila River near Tacna, Arizona.....Populations of Sonora Clapper Rails were discovered as permanent residents in five separate mangrove swamps along the west coast of Mexico in the vicinity of Kino Bay, Sonora. These observations were farther north than any heretofore reported for the race R. l. rhizophorae, and the swamps also represent the extreme northward limit of mangroves in Sonora.....During the winter, Yuma clappers did not respond to taped calls north of the International Boundary, whereas clappers along the coast of Sonora readily answered the calls during the same period of time. We conclude that most Yuma Clapper Rails migrate from their summer habitat along the Colorado River in September and do not return to the breeding areas until late April.

Condor↗