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Results for “Wilson Journal of Ornithology”

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At least 109 records · Page 6Linked to original sources
USGS2017

Timing of autumn migration of Sora (Porzana carolina) in Missouri

Monitoring and conserving waterbirds, including Sora ( Porzana carolina ), in Missouri, is constrained by the lack of information on migration phenology. We performed nocturnal distance sampling surveys by ATV across 11 state and federal managed wetlands in Missouri, USA from 2012–2015 to compare the timing of Sora' autumn migration among years. Migration of Sora in Missouri began in the first week of August, on average it peaked on 25 September, and continued through the last week of October. We detected migration of Sora earlier in autumn than did previous work. We found the start and end of migration did not vary annually in 3 of 4 years. With our results, wetland managers should be able to better time their management for rails in Missouri.

Missouri↗
USGS2018

Visual cues for woodpeckers: light reflectance of decayed wood varies by decay fungus

The appearance of wood substrates is likely relevant to bird species with life histories that require regular interactions with wood for food and shelter. Woodpeckers detect decayed wood for cavity placement or foraging, and some species may be capable of detecting trees decayed by specific fungi; however, a mechanism allowing for such specificity remains unidentified. We hypothesized that decay fungi associated with woodpecker cavity sites alter the substrate reflectance in a species-specific manner that is visually discriminable by woodpeckers. We grew 10 species of wood decay fungi from pure cultures on sterile wood substrates of 3 tree species. We then measured the relative reflectance spectra of decayed and control wood wafers and compared them using the receptor noise-limited (RNL) color discrimination model. The RNL model has been used in studies of feather coloration, egg shells, flowers, and fruit to model how the colors of objects appear to birds. Our analyses indicated 6 of 10 decayed substrate/control comparisons were above the threshold of discrimination (i.e., indicating differences discriminable by avian viewers), and 12 of 13 decayed substrate comparisons were also above threshold for a hypothetical woodpecker. We conclude that woodpeckers should be capable of visually detecting decayed wood on trees where bark is absent, and they should also be able to detect visually species-specific differences in wood substrates decayed by fungi used in this study. Our results provide evidence for a visual mechanism by which woodpeckers could identify and select substrates decayed by specific fungi, which has implications for understanding ecologically important woodpecker–fungus interactions.

Wilson Journal of Ornithology↗
USGS2018

Rapid departure of Roseate Terns (Sterna dougallii) following large-scale nest failure

Nest failure of most pairs of Roseate Terns (Sterna dougallii) at Falkner Island, Connecticut, in 2002-2003 (due mainly to predation by Black-crowned Night-herons [Nycticorax nycticorax]) was followed by the rapid departure of many of the failed individuals in both years. Nine failed pairs (16.7%) stayed while 40 (74.1%) of 54 unsuccessful pairs left within 2 d following nest failure in 2002, and 7 pairs (21.9%) stayed while 25 (78.1%) of 32 unsuccessful pairs left within 2 d in 2003. Individuals that departed this colony site by the end of June likely had time to prospect and renest at another colony site in the same year, and individuals that successfully renested at another colony site could have shown reduced colony-site fidelity to Falkner Island in subsequent years.

Connecticut↗
USGS2018

Nest mortality of sagebrush songbirds due to a severe hailstorm

Demographic assessments of nesting birds typically focus on failures due to nest predation or brood parasitism. Extreme weather events such as hailstorms, however, can also destroy eggs and injure or kill juvenile and adult birds at the nest. We documented the effects of a severe hailstorm on 3 species of sagebrush-associated songbirds: Sage Thrasher ( Oreoscoptes montanus ), Brewer's Sparrow ( Spizella breweri ), and Vesper Sparrow ( Pooecetes gramineus ), nesting at eight 24 ha study plots in central Wyoming, USA. Across all plots, 17% of 128 nests failed due to the hailstorm; however, all failed nests were located at a subset of study plots ( n = 3) where the hailstorm was most intense, and 45% of all nests failures on those plots were due to hail. Mortality rates varied by species, nest architecture, and nest placement. Nests with more robust architecture and those sited more deeply under the shrub canopy were more likely to survive the hailstorm, suggesting that natural history traits may modulate mortality risk due to hailstorms. While sporadic in nature, hailstorms may represent a significant source of nest failure to songbirds in certain locations, especially with increasing storm frequency and severity forecasted in some regions with ongoing climate change.

Wilson Journal of Ornithology↗
USGS2018

Confirmation of diving and swimming behavior in the Sora (Porzana carolina)

We first observed Sora ( Porzana carolina ) swimming and diving under water while capturing them with hand nets at night. Since that time, we have observed the behavior several times and documented it with photos and video. Rails are among the most elusive birds. Despite living in wetlands, water depth has often been discussed as a factor limiting habitat use by rails, with the assumption that when water levels are too deep, rails walk on top of floating or emergent vegetation. Here we present new photo and video evidence that confirms previous observations that Sora are adept at swimming and diving in deep water wetland environments, which should alter how we think about their ability to avoid predators and use deeper water habitats.

Wilson Journal of Ornithology↗
USGS2018

Post-fledging movements and habitat associations of White-tailed Sea Eagles (Haliaeetus albicilla) in Central Asia

Behavior of young birds can have important consequences for population dynamics. We investigated the autumnal post-fledging movements of 3 White-tailed Sea Eagles (Haliaeetus albicilla) hatched in Kazakhstan. All 3 eagles traveled south, flying on average 25–108 km/d. Movement was nonrandom, with eagles generally traveling near mosaics of forest, open areas, and water, and rarely using areas with little vegetation. As the first study of movements of White-tailed Sea Eagles in arid Central Asia, this study provides insight into potential limiting factors and how these birds interact with their environment during long-distance movements.

Wilson Journal of Ornithology↗
USGS2019

Characteristics of feeding sites of California Condors (Gymnogyps californianus) in the human-dominated landscape of Southern California

Wildlife conservation is often improved by understanding the movement ecology of species and adapting management strategies to dynamic conditions associated with movement. Despite a remarkable recovery over the past 30 year, the establishment of self-sustaining populations of California Condors (Gymnogyps californianus) has been challenging in the human-dominated landscapes of southern California. Among these challenges are those imposed by condor ground-foraging behavior that exposes them to environmental contamination. These include lead poisoning from the ingestion of spent ammunition and micro-trash ingestion and, during takeoff and landing, collisions with human structures. We tracked 28 California Condors for 24 months with patagially mounted GPS telemetry units to investigate the characteristics of ground sites condors visited and to identify spatiotemporal trends that might aid in conservation of this critically endangered species. Ground sites occurred on a wide variety of land cover types, primarily on steep slopes, and those more frequently used were associated with open cover. Condors concentrated their visits to ground sites around a 3 h period near midday, and usage increased from winter to late summer. Our study is the first to use remotely sensed telemetry data to describe fine-scale ecological correlates of condor ground-foraging ecology and therefore has important relevance for ongoing conservation and management strategies for this species. The descriptions of ground sites we provide can be used to target conservation or management actions.

California↗
USGS2019

Reproductive biology of Grey-breasted Wood-Wren (Henicorhina leucophrys): A comparative study of tropical and temperate wrens

We provide a detailed breeding biology account for the Grey-breasted Wood-Wren ( Henicorhina leucophrys ) and a comparison of the reproductive life history of tropical and temperate wrens using literature data. We conducted this study at Yacambú National Park in Venezuela from 2002 to 2008. Clutch size was 1.99 (SE 0.01) and fresh egg mass was 2.35 g (0.02). Females incubated the eggs for 19.74 d (0.37), and nestlings left nests at 17.37 d (0.18). Nest attentiveness (percent time spent on the nest) increased across the incubation period while brooding attentiveness decreased as nestlings aged. Brooding effort began with similar attentiveness as at the end of incubation. Food provisioning rate and feeding rate per nestling increased as nestlings aged. Growth rates ( K ) based on mass, tarsus, and wing chord were relatively slow at 0.375, 0.246, and 0.257, respectively. The nesting season extended from mid-March to late June for 7 years and the average nesting season length was 64.5 d (3.68) with a median of May 4. Nest success was 22%. Nest predation was the cause of 77% of nest failures with a total daily predation rate of 0.030 (0.002). Results obtained from the literature demonstrated that tropical wrens averaged smaller clutch sizes and longer incubation periods than relatives in the temperate region.

Yacambú National Park↗
USGS2019

Roost- and perch-site selection by Golden Eagles (Aquila chrysaetos) in eastern North America

Birds select critical resources to meet needs that vary in response to spatial, temporal, and individual variation. As an example, perch or roost sites may be at locations that provide protection from predators, mobbing, or inclement weather. Applied to large, soaring predators, this theory suggests that they may select perch and roost sites near food resources or at sites where environmental updrafts develop. To test these theories, we characterized selection of nonflight locations throughout the annual cycle for Golden Eagles ( Aquila chrysaetos ) in eastern North America. We determined factors associated with selection of perching (daytime) and roosting (nighttime) sites by eagles by comparing land cover and topographic characteristics of GPS telemetry locations for eagles (used) with random (available) locations. We separately assessed selection for perch and roost sites during each of 4 seasons (winter, summer, and spring and fall migration). Golden Eagles showed different selection patterns for perching by season and age. Throughout the year, eagles selected perch sites on steep slopes. The direction these slopes faced differed among seasons, with eagles selecting south-facing slopes in summer and east-facing slopes during migration. Adults showed greater preferences for broadleaf forests in summer and for ridges in fall. Patterns of perch-site use were consistent with selection for sites that provide thermal protection and access to thermal updrafts. We found few patterns of selection for roosting sites. Our analysis provides insight into decision-making by a longdistance migrant across its annual cycle and throughout its geographic range, and thus into how resource selection changes seasonally.

Wilson Journal of Ornithology↗
USGS2019

Novel ectoparasite infestation on Yuma ridgway's rails (Rallus obsoletus yumanensis)

Yuma Ridgway's Rails ( Rallus obsoletus yumanensis ) are federally endangered birds endemic to wetlands throughout the Lower Colorado River Basin in Nevada, California, Arizona, and Mexico. The U.S. population has declined in recent years for unknown reasons. We documented a novel and severe chigger mite infestation in the Yuma Ridgway's Rails in southwestern Arizona in 2017. Prevalence of the infestation was spatially heterogeneous: 92% (48 of 52) of the Yuma Ridgway's Rails that we captured at Imperial National Wildlife Refuge were infested, whereas only 11% (2 of 18) of the Yuma Ridgway's Rails at Cibola National Wildlife Refuge were chigger infested. We know little about the origin of this infestation or the impacts of the parasites on the behavior and fitness of Yuma Ridgway's Rails. However, ectoparasite infestations in other species have caused population declines and the intensity and novelty of this ectoparasite infestation, combined with population status of this species, warrants immediate attention to this issue and further study of these ectoparasites.

Arizona, California↗
USGS2019

Annual survival, site fidelity, and longevity in the eastern coastal population of the Painted Bunting (Passerina ciris) based on a 20-year mark-recapture/resighting study

A long-term study of annual survival, longevity, and site fidelity in the eastern coastal population of the Painted Bunting (Passerina ciris) during the breeding season was conducted from 1999 through 2018 in the outer coastal plain of the southeastern Atlantic coast of the United States. Painted Buntings were uniquely color-banded from 1999 through 2003 at 40 study sites that were paired at 20 locations from southeastern North Carolina south to northeastern Florida. Survival analysis used capture histories through 2005 for 994 birds banded as hatch-year and 2420 birds banded as post-hatch-year (adults). Annual estimates of apparent survival (1999-2004) averaged 0.71 and 0.66 for adult males and females, respectively, and 0.33 for hatch-year birds. We did not find evidence that survival differed in relation to latitude or extent of human development near study sites, although estimates for adult females were higher for birds banded on sheltered islands compared to the mainland. Expected time in the population, based on estimated survival, was 3.9 and 3.4 years for adult males and females, respectively. The oldest observed birds were a 14-year old male observed in June 2016 at Harris Neck NWR, Georgia, the site at which he had been banded in July 2003 as a second-year bird, and a 13-year old male seen at Ft. George Island, Florida in June 2016, 2 km across a tidal estuary from the site where the bird was banded in August 2003 as hatch-year. The males were sighted at these two sites in 9 and 11 different years, respectively. Overall, 78% (males) and 81% (females) of re-sightings and re-captures of birds banded as adults occurred at the same study site where individuals were banded, compared to 59% (males) and 60% (females) of birds banded as hatch-year. Known mortalities of banded buntings included nine birds trapped for the caged-bird trade. This study shows the potential for high survival and longevity in the eastern coastal population of the Painted Bunting, and given evidence of high site fidelity in the breeding range, the vulnerability of the population to human development along the southeastern U.S. coast as well as to illegal trapping.

Wilson Journal of Ornithology↗
USGS2019

Louisiana Waterthrush (Parkesia motacilla) survival and site fidelity in an area undergoing shale gas development

We quantified Louisiana Waterthrush ( Parkesia motacilla ) site fidelity and apparent survival across a 6 year period in an area undergoing shale gas development.Waterthrush initially exhibited high site fidelity that declined over time. At the same time, the number of unpaired males defending territories increased as did natal fidelity. We identified site fidelity factors that influenced if adult males and females returned. More males returned either due to or regardless of amount of shale gas disturbance and lower riparian habitat quality. Females were less likely to return with increased number of breeding attempts. Females in shale gas disturbed areas had a higher number of breeding attempts and lower individual productivity. We saw a general nonsignificant trend in declining apparent survival over time. Overall apparent survival estimates for adult males (0.56) and females (0.44) were similar to those reported for other populations. Apparent survival candidate models suggested weak, positive relationships of increased survival with shale gas territory disturbance, disturbance with year, and year for adult males, and a positive relationship of increased survival with hydraulic fracturing runoff for adult females although regression coefficients overlapped zero for all model-supported covariates implying no statistical significance. Since waterthrush can maintain pair bonds from the previous year and females must pick a nest site within the defended male's territory, there are potential conflicts between factors that influence adult survival and site fidelity that may affect long-term population persistence. Our study adds to previous evidence that shale gas disturbed areas may serve as sink habitats.

West Virginia↗
USGS2021

Local fruit availability and en route wind conditions are poor predictors of bird abundance and composition during fall migration in coastal Yucatán Peninsula

In migratory stopover habitats, bird abundance and composition change on a near daily basis. On any given day, the local bird community should reflect local environmental conditions but also the environments that birds encountered previously along their migratory route. For example, during fall migration, the coast of the Yucatán Peninsula in Mexico receives birds that have just crossed the Gulf of Mexico and their abundance and composition may be associated with regional factors such as wind conditions experienced on previous dates. Other factors, such as local fruit availability, may also influence daily variation in bird abundance and composition. Using mist net data from 2 coastal national parks in the Yucatán Peninsula during fall migration in 2016 and 2017, we did not find a strong association between daily changes in bird abundance or community composition with wind conditions and ripe fruit availability. Thus, despite wind and fruit being known to be important to individual birds (influencing stopover duration and departure decisions), their effects might not scale up to be drivers of population and community level variation. On the other hand, we found that the 2 sites shared only about half of their species and those shared species had different temporal abundance patterns at each site. Site and year differences in temporal patterns of migration might arise because populations of the same species are on different migration routes and schedules. While bird arrival is not timed to hit peaks in fruit production in our study sites, whether bird–resource mismatch is a general characteristic of tropical coastal stopover habitats requires further research. If birds on migration have adapted to seasonal variation in food availability, they might be equipped to deal with the additional variability in food supply that is expected to occur with climate change.

Yucatan Peninsula↗
USGS2021

Nest site selection of White-tailed Hawks (Geranoaetus albicaudatus) on Texas barrier islands

The distribution of the White-tailed Hawk ( Geranoaetus albicaudatus ) in the United States is restricted to the prairies and savannas of the Gulf Coastal Plain of Texas. Although listed as a state threatened species, it remains one of the least studied raptors in North America. It appears to reach high densities on some Texas barrier islands despite the island vegetation communities being structurally simple and providing few nesting substrates. We compared vegetation and landscape characteristics for sets of White-tailed Hawk nest sites and random sites on 3 Texas barrier islands (Matagorda, Mustang, and North Padre) representing a gradient of low to high human presence and impact. We constructed model sets consisting of vegetation and landscape features measured at a random subsample of nest sites and random sites, then assessed model sets with logistic regression. Our best constructed model correctly differentiated 83% of nest sites from random sites on Matagorda Island, 70% on Mustang Island, and 50% on North Padre Island. Overall, it appears that the structure of nest substrates was important to White-tailed Hawk nest-site selection: shrubs categorized as densely structured with or without thorns accounted for 78% of nest substrates compared to only 13% of paired, random potential substrates. The most frequently selected nest substrates overall were yaupon ( Ilex vomitoria ; 43%) and Macartney rose ( Rosa bracteata ; 24%). If White-tailed Hawks are to be conserved on the barrier islands, a balance will need to be found between continued anthropogenic development, maintenance of habitat patches, and availability of suitable nesting substrates.

Texas↗
USGS2021

Spatial and temporal overlap between foraging shorebirds and spawning horseshoe crabs (Limulus polyphemus) in the Cape Romain-Santee Delta Region of the U.S. Atlantic coast

Shorebird use of horseshoe crab ( Limulus polyphemus ) eggs as food items has been well documented along the Atlantic coast of the United States at northeastern stopover sites such as the Delaware Bay. However, the relationship between migratory shorebirds and horseshoe crab eggs has not been well studied in the South Atlantic Bight. The objective of our study was to assess the spatial and temporal overlap between the density of horseshoe crab eggs and the relative abundance of foraging shorebirds during spring migration in the Cape Romain-Santee Delta Region (CRSD), South Carolina, USA. The CRSD is a site of international importance for shorebirds that supports ∼100,000 shorebirds annually. We also sought to determine if horseshoe crab eggs were present in the diets of shorebirds at these sites. We monitored study plots between March and June 2015–2016 at predicted horseshoe crab spawning sites on beaches throughout Cape Romain National Wildlife Refuge. We conducted weekly shorebird surveys and collected core samples of beach substrate twice per month to measure densities of horseshoe crab eggs. We found a positive correlation between number of foraging shorebirds and horseshoe crab eggs for both years. In a molecular analysis of shorebird fecal samples, 95% of the samples tested contained DNA from horseshoe crab eggs. The spatial and temporal overlap between shorebirds and horseshoe crab eggs, and the dietary analysis of fecal samples, suggest that there are areas of localized horseshoe crab spawning that shorebirds can utilize as a food source during spring in Cape Romain National Wildlife Refuge.

South Carolina↗
USGS2022

Intrabrood variation in nestling mass among three sagebrush-associated songbirds

The young of some altricial bird species hatch asynchronously, which can lead to considerable size differences among siblings. Nestling traits such as body mass, moreover, can carry over and influence post-fledging survival. Despite the potential importance of nestling mass for reproductive outcomes, however, variation in nestling mass and relationships with brood size has been described and quantified rarely. We weighed 453 nestlings from 148 nests of 3 sympatric, sagebrush-associated songbird species in Wyoming, USA, to describe the range of intrabrood mass differences. Intrabrood differences in nestling mass were greatest for the largest species, the Sage Thrasher ( Oreoscoptes montanus ), for which the smallest nestling in a brood was on average 26.2% smaller than the largest. The smaller Vesper Sparrow ( Pooecetes gramineus ) and Brewer's Sparrow ( Spizella breweri ) exhibited similar intrabrood mass ratios, with the smallest nestling being 17.4% and 18.4% smaller on average than the largest for the 2 species, respectively. For each additional nestling within a brood, the smallest nestling was an additional 6.6–13.6% smaller than the largest nestling, depending on species. Understanding the extent of intrabrood variation in nestling traits has important implications for the productivity of species facing unpredictable environments.

The Wilson Journal of Ornithology↗
USGS2021

Egg morphometrics and egg shape coefficients for White-faced Ibis (Plegadis chihi)

Egg size is a useful metric for maternal investment, offspring quality, and contaminant studies. Yet these values and the egg shape coefficients required to estimate egg size are not available for many species, including White-faced-Ibis ( Plegadis chihi ). We provide egg morphometrics derived from 319 White-faced Ibis eggs sampled at Bear River Migratory Bird Refuge, Great Salt Lake, Utah, from 2010 to 2012. Measured egg length (mean ± SD) was 51.20 ± 1.99 mm, egg width was 36.08 ± 1.15 mm, and whole egg mass was 34.1 ± 3.3 g. Estimated whole egg volume was 34.63 ± 3.73 cm 3 and estimated egg shape coefficients were 0.507 for K v (whole egg and egg contents), 0.547 for K w (whole egg), and 0.524 for K w (egg contents only). In addition, we documented expected declines in egg mass over time due to incubation (–0.22 g/d) and desiccation during storage (–0.03 g/d), that should be accounted for prior to analyses that use egg mass of freshly laid eggs.

Utah↗
USGS2022

Molt patterns, aging criteria, and molt-breeding seasonality of 8 native forest birds from the Island of Hawaiʻi

Much of our knowledge on the patterns and timing of breeding and molting come from studies of temperate region birds, yet tropical birds can have markedly different phenologies. The Hawaiian Islands support multiple endemic bird species that have evolved for millions of years in isolation to a tropical environment with minimal seasonality. We examined data from multiple studies (1994–2020) conducted across the avian annual cycle, from multiple locations, to evaluate molt patterns and establish criteria for assignment of age and sex based on the WRP, or molt-cycle age classification system designed specifically for tropical species. In addition, we describe the phenologies of molt and breeding and quantify the differences in males and females based on plumage coloration and morphometrics for 8 native species. We were able to validate the WRP tropical bird aging system as an appropriate method for aging forest birds from the Island of Hawaiʻi and separate all 8 species examined into juvenile, formative, and definitive plumages based on feather patterns and molt limits. Additionally, 2 species had distinctive second basic plumages. All 8 species examined also had extended periods of breeding and molting unlike their familial temperate counterparts, but these high energy activities are largely partitioned into separate time periods. Each species had some degree of overlap in breeding and molting, but the frequency of individuals that were simultaneously in breeding condition and molting was low with only 2 species displaying a proportion of overlap greater than 10% among all captures. Accurate aging and sexing techniques improve the quality of data from banding studies and provide important information on how species adapt to their environments.

Hawai'i↗