bluuebunny/crossref_metadata_2025_split huggingface dataset:
Survival and Natal Dispersal of Juvenile Snowy Plovers (Charadrius Alexandrinus) in Central Coastal California
Authors: Stenzel Lynne E. , Page Gary W. , Warriner Jane C. , Warriner John S. , George Douglas E. , Eyster Carleton R. , Ramer Bernadette A. , Neuman Kristina K. 
Published: September 2019

AbstractJuvenile survival and dispersal rates are important demographic parameters in predicting the viability of avian populations, but estimates are seldom available because mortality is usually confounded with permanent natal dispersal in analyses of live-encounter data. We used the Barker model for combined captures, recoveries, and resightings to estimate juvenile survival in fledgling Snowy Plover (Charadrius alexandrinus) for the 6.5-to-10.5-month period between fledging at 28 days and 1 April the following year, on the central California coast, for a 16-year period, 1984-1999. By using a large body of year-round sighting data from throughout the species' Pacific-coast range, we estimated true survival and quantified natal dispersal rates and distances. Juvenile survival estimates varied annually between 0.283 ± 0.028 (mean ± SE) and 0.575 ± 0.061 with no trend over the study, and paralleled higher adult survival in our most parsimonious models. In comparison, annual survival of banded chicks from hatching to fledging at age 28 days was 0.285–0.483 (x̄ = 0.382 ± 0.014 SE) for those 16 years. Males were more likely to disperse from Monterey Bay for winter and females were more likely to disperse for breeding. Dispersal distances to breeding sites were usually within 10 km of natal sites (64%) and seldom >50 km (16%). The present study provides the first estimate of true survival for a juvenile shorebird and new information on survival and dispersal rates that will be useful for modeling Snowy Plover population viability. Studies of local winter residents, focused on predator pressure and weather conditions, could further advance our understanding of factors determining Snowy Plover survival.Supervivencia y Dispersión Natal de Juveniles de Charadrius alexandrinus en la Costa Central de California
Detecting Population Trends in Migratory Birds of Prey
Authors: Farmer Christopher J. , Hussell David J. T. , Mizrahi David 
Published: September 2019

Abstract
Counts of visible migrants at traditional watchsites throughout North America provide an opportunity to augment population-monitoring efforts for birds of prey. We analyzed hourly counts of migrating raptors at one inland (Hawk Mountain Sanctuary, Pennsylvania) and one coastal (Cape May Point, New Jersey) watchsite in northeastern North America. Hourly counts of migrants have been collected for 38 years at Hawk Mountain Sanctuary and for 28 years at Cape May Point. We compared effort-adjusted, arithmetic-mean passage rates to five geometric-mean indexes for 12 species. We used reparameterized polynomial regression to estimate trends in the indexes and to test the significance of trends from 1976–1978 (average index over three-year period) to 2001–2003. Effort-adjusted, arithmetic-mean indexes corresponded to more sophisticated indexes on the complete data sets but did not perform well on simulated data with missing observation days. We recommend the use of a regression-based, date-adjusted index for the analysis of hawk-count data. This index produced trends similar to other geometric-mean indexes, performed well on data sets simulating reduced sampling frequency, and outperformed other indexes on data sets with large blocks of missing observation days. Correspondence between trends at the watchsites and trends from Breeding Bird Surveys (BBSs) suggests that migration counts provide robust estimates of population trends for raptors. Furthermore, migration counts allow the monitoring of species not detected by BBS and produce trends with greater precision for species sampled by both methods. Analysis of migration counts with appropriate methods holds considerable promise for contributing to the development of integrated strategies to monitor raptor populations.
Detección de Tendencias Poblacionales en Aves de Presa Migratorias
Stopover Habitat use by Spring Migrant Landbirds: The Roles of Habitat Structure, Leaf Development, and Food Availability
Authors: Rodewald Paul G. , Brittingham Margaret C. 
Published: September 2019

AbstractStopover habitat quality may influence the abundance of migrant landbirds, yet little is known about how spatial and temporal changes in stopover habitat quality influence the use of habitats by migrant landbirds. From late April to late May, 1997–1999, we surveyed migrant landbirds within five habitats (early successional shrub-sapling-stage forest, midsuccessional pole-stage forest, mature forest interior, mature forest-agricultural edge, and mature suburban forest) in central Pennsylvania. To assess relative quality of stopover habitats, we measured species abundance, species richness, and foraging behavior of Yellow-rumped Warblers (Dendroica coronata). We measured vegetation structure and phenology to examine proximate cues of potential importance in habitat selection. Of nine transient (nonbreeding) species analyzed, seven-Least Flycatcher (Empidonax minimus), Nashville Warbler (Vermivora ruficapilla), Northern Parula (Parula americana), Magnolia Warbler (D. magnolia), Black-throated Blue Warbler (D. caerulescens), Yellow-rumped Warbler, and Blackpoll Warbler (D. striata)-were most abundant in mature forests, and especially edge-dominated mature forests (forest-agricultural edge and suburban forest). Habitats used by mature-forest-breeding transients changed between years, but edge-dominated forest types were used most frequently in all three years. Although canopy leaf development at mature forest sites showed little relationship to site use by mature-forest-breeding transients within weekly intervals, year-to-year differences in leaf phenology were consistent with year-to-year changes in habitat use by migrant landbirds. Foraging behavior of Yellow-rumped Warblers suggested higher food availability and quality in forest-agricultural edges, compared with suburban forest and forest interior. Mature-forest-breeding transients were positively associated with sites that had large trees (>38 cm diameter at breast height) and denser understory vegetation (stems 0–2.5 cm in diameter). Extensive use of mature edge-dominated forests by migrating forest birds during spring suggests that these habitats may be important for the conservation of migrant landbirds.Uso de Hábitat durante las Escalas Migratorias por Aves Migratorias Terrestres: el Papel de la Estructura del Hábitat, el Desarrollo de las Hojas y la Disponibilidad de Alimento
Parrots of the World: An Identification Guide.
Authors: Iñigo-Elias Eduardo E. 
Published: September 2019

Abstract
The following critiques express the opinions of the individual evaluators regarding the strengths, weaknesses, and value of the books they review. As such, the appraisals are subjective assessments and do not necessarily reflect the opinions of the editors or any official policy of the American Ornithologists' Union.
A Distinctive New Species of Tyrant Flycatcher (Passeriformes: Tyrannidae: Cnipodectes) From Southeastern Peru
Authors: Lane Daniel F. , Servat Grace P. , Valqui H. Thomas , Lambert Frank R. 
Published: September 2019

AbstractWe describe a distinctive new species of twistwing (Tyrannidae: Cnipodectes) from southeastern Peru. Despite extensive ornithological research in the region, this species has escaped notice, which suggests that it may be restricted to larger blocks of forest dominated by bamboo (Guadua spp.), a habitat poorly surveyed in Amazonia. Currently known from only a few sites in the departments of Madre de Dios and Cuzco, the species appears to be a Guadua specialist, though its life history is very poorly known. To date, the only other species of Cnipodectes, C. subbrunneus (Brownish Twistwing), is not known from most of southeastern Peru.Una Nueva Especie Distintiva del Género Cnipodectes (Passeriformes: Tyrannidae) del Sureste de Perú
Short-Term Response of Forest Birds to Experimental Clearcut Edges
Authors: Villard Marc-André , Schmiegelow Fiona K. A. , Trzcinski M. Kurtis 
Published: September 2019

Abstract
Numerous studies have addressed the potential consequences of increasing the density of edges through human activities, but most have documented responses to existing edges. Here, we monitored the response of seven forest bird species to experimentally created edges around five plots (10 ha, n = 3; 25 ha, n = 2) in the boreal mixed-wood forest of Alberta, Canada. We also mapped bird detections in six control plots (10 ha, n = 5; 25 ha, n = 1). The focal species were Least Flycatcher (Empidonax minimus), Red-eyed Vireo (Vireo olivaceus), Yellow-rumped Warbler (Dendroica coronata), Black-throated Green Warbler (D. virens), Ovenbird (Seiurus aurocapilla), Mourning Warbler (Oporornis philadelphia), and White-throated Sparrow (Zonotrichia albicollis). In the two breeding seasons following experimental clearcutting, we quantified birds' responses to edges in the absence of substantial edge-induced changes in vegetation by comparing the distribution of detections between treatment and control plots. We predicted that forest-edge specialists would be attracted to edges, forest-interior specialists would avoid them, and interior-edge generalists would show a neutral response. None of these predictions was consistently supported among plots and years, except in the Mourning Warbler. However, none of the significant responses was the opposite of predictions. We also predicted that postharvest colonization of treated plots would mainly involve forest-edge specialists, whereas most local extinctions would involve forest-interior specialists. Only the colonization of 10-ha fragments followed the predicted pattern. The relatively neutral response to forest edges we observed suggests that, in general, boreal forest birds do not respond to the edge itself or to proximate cues of edge proximity. Rather, significant responses may be delayed until edge-to-interior gradients in vegetation are established.
Respuestas a Corto Plazo de las Aves de Bosque a Bordes Creados Experimentalmente por Tala Rasa
Behavioral Paternity Predicts Genetic Paternity in Satin Bowerbirds (Ptilonorhynchus Violaceus), A Species With a Non-Resource-Based Mating System
Authors: Reynolds Sheila M. , Dryer Katie , Bollback Jonathan , Uy J. Albert C. , Patricelli Gail L. , Robson Timothy , Borgia Gerald , Braun Michael J. 
Published: September 2019

AbstractThe potential for differences between genetic paternity and paternity inferred from behavioral observation has long been recognized. These differences are associated with the challenge for females of seeking both genetic and material benefits; this challenge is less severe in species with polygynous, non-resource-based mating systems (such as leks) than in those with resource-based systems. We present the first study of paternity patterns in a non-resource-based species that does not form true leks. We compared paternity inferred from observed mating behavior to genetically assigned paternity in the Satin Bowerbird (Ptilonorhynchus violaceus) using eight microsatellite markers. Mating behavior was observed and recorded via automated video-cameras positioned at all bowers (29–34 bowers each year) in the study site throughout each mating season. We obtained blood samples and identified mothers for 11 chicks in 9 nests. For all chicks, the most likely genetic father had been observed to mate with the mother in the year the chick was sampled. All most likely genetic fathers were assigned with high confidence and all were bower-holding males. These results demonstrate that genetic paternity can be inferred from observed mating behavior with reasonable confidence in Satin Bowerbirds. Observed male mating-success is therefore a reliable predictor of reproductive success, and this suggests that high skew in observed male mating-success translates directly to high skew in reproductive success.La Paternidad Comportamental Predice la Paternidad Genética en Ptilonorhynchus violaceus, una Especie con un Sistema de Apareamiento que No Está Basado en los Recursos
Flyway-Scale Variation in Plasma Triglyceride Levels as an Index of Refueling Rate in Spring-Migrating Western Sandpipers (Calidris Mauri)
Authors: Williams Tony D. , Warnock Nils , Takekawa John Y. , Bishop Mary Anne 
Published: September 2019

Abstract
We combined radiotelemetry, plasma metabolite analyses, and macro-invertebrate prey sampling to investigate variation in putative fattening rates (estimated as plasma triglyceride levels) at the flyway scale in Western Sandpipers (Calidris mauri) migrating between Punta Banda, Mexico (31°N), and Hartney Bay, Alaska (60°N), a distance of 4,240 km. Birds were caught at a wintering site (San Francisco Bay) and eight stopover sites along this Pacific Flyway. Body mass was higher in females than in males at six sites, but variation was not correlated with latitude for either sex, and the relationship of change in mass by date within sites was uninformative with regard to possible latitudinal variation in fattening rates. At San Francisco Bay, triglyceride levels were higher in the spring than in the winter. Mean plasma triglyceride varied among stopover sites, and there was a significant linear trend of increasing triglyceride levels with latitude as birds migrated north. At San Francisco Bay, length of stay was negatively related to triglyceride levels. However, plasma triglyceride levels at wintering or initial stopover sites (San Francisco and Punta Banda) did not predict individual variation in subsequent rates of travel during migration. We found no significant relationship between triglyceride levels and prey biomass at different stopover sites, which suggests that the latitudinal pattern is not explained by latitudinal changes in food availability. Rather, we suggest that differences in physiology of migratory birds at southern versus northern stopover sites or behavioral differences may allow birds to sustain higher fattening rates closer to the breeding grounds.
Variación a la Escala de Corredores de Vuelo en los Niveles de Triglicéridos Plasmáticos como un Índice de la Tasa de Reabastecimiento durante la Migración de Primavera en Calidris mauri
Early Infestation by Bot Flies (Philornis Seguyi) Decreases Chick Survival and Nesting Success in Chalk-Browed Mockingbirds (Mimus Saturninus)
Authors: Rabuffetti Fabián L. , Reboreda Juan C. 
Published: September 2019

AbstractBot flies (Diptera: Muscidae: Philornis spp.) are a group of flies comprising mostly species with a Neotropical distribution. Their larvae parasitize several species of birds, living subcutaneously on altricial chicks. We investigated the effect of parasitism by bot flies (P. seguyi) on the reproductive success of Chalk-browed Mockingbirds (Mimus saturninus) in temperate grasslands near the southern limit of bot fly distributions. We analyzed seasonal variation of bot fly prevalence during three consecutive years and how the timing and intensity of bot fly infestation affected growth and survival of Chalk-browed Mockingbird nestlings. Bot fly prevalence was 58.3%, 30.7%, and 45.5% each year, and in all years, it increased with time of breeding. Most of the infested nests fledged no chicks. In these nests, chicks had a lower tarsus growth rate than in noninfested nests and died 3–4 days after parasitism. The average time from hatching of the first chick until infestation was 4.4 days. The age of the chicks at the time of infestation was associated positively with nesting success and negatively with intensity of parasitism. Bot fly parasitism also reduced the survival of Shiny Cowbird (Molothrus bonariensis) chicks present in Chalk-browed Mockingbird nests, but the presence of Shiny Cowbird chicks did not affect timing of infestation or fledging success of Chalk-browed Mockingbird chicks. Our results show that an intermediate prevalence of bot fly parasitism produces an important decrease in the reproductive success of Chalk-browed Mockingbirds and suggest that bot flies may play an important role as selective agents in the evolution of host life-history strategies.La Infestación Temprana con Larvas de Philornis seguyi Disminuye la Supervivencia de los Pichones y el Éxito de Nidificación de Mimus saturninus
Use of Juvenal Plumage in Diagnosing Species Limits: An Example Using Buntings in the Genus Plectrophenax
Authors: Maley James M. , Winker Kevin 
Published: September 2019

AbstractSpecies limits in the genus Plectrophenax have been difficult to assess. McKay’s Buntings (Plectrophenax hyperboreus) are very similar both morphologically and behaviorally to Snow Buntings (P. nivalis). However, their breeding ranges are allopatric, and there is limited evidence of gene flow. The juvenal plumage of McKay’s Buntings has never been described as different from that of Snow Buntings. Comparison of a series of McKay’s Buntings in juvenal plumage with a series of Snow Buntings in juvenal plumage showed clear differences between the two forms. We used color spectrophotometry to quantify the differences between the two taxa in two areas of the body that appeared to be consistently different, the throat and back. The relative magnitude of the difference between McKay’s and Snow buntings was greater than homologous differences between two subspecies of Snow Bunting (P. n. nivalis and P. n. townsendi). Four out of six variables were significantly different between McKay’s and Snow buntings, whereas none of the variables were significantly different between the two subspecies of Snow Bunting. Bonferroni corrected t-tests of sexual dimorphism and regression of the variables against year of collection showed that these factors were not associated with these differences. Discriminant analysis accurately separated 100% of the specimens into their respective groups. These differences are notable given the evolutionarily conservative nature of juvenal plumage. Our results support continued recognition of McKay’s Bunting as a species and reconfirm the use of juvenal plumage to help determine species limits.Uso del Plumaje Juvenil para Diagnosticar los Límites entre Especies: un Ejemplo en el Género Plectrophenax
An Assessment of Song Admixture as an Indicator of Hybridization in Black-Capped Chickadees (Poecile Atricapillus) and Carolina Chickadees (P. Carolinensis)
Authors: Sattler Gene D. , Sawaya Patricia , Braun Michael J. 
Published: September 2019

AbstractVocal admixture often occurs where differentiated populations or species of birds meet. This may entail song sympatry, bilingually singing birds, and songs with intermediate or atypical characteristics. Different levels of vocal admixture at the range interface between Black-capped Chickadees (Poecile atricapillus) and Carolina Chickadees (P. carolinensis) have been interpreted as indicating that hybridization is frequent at some locations but not others. However, song ontogeny in these birds has a strong nongenetic component, so that inferences regarding hybridization based on vocal admixture require confirmation. We used diagnostic genetic markers and quantitative analyses of song to characterize population samples along two transects of the chickadee contact zone in the Appalachian Mountains. More than 50% of individuals at the range interface were of hybrid ancestry, yet only 20% were observed to be bilingual or to sing atypical songs. Principal component analysis revealed minimal song intermediacy. This result contrasts with an earlier analysis of the hybrid zone in Missouri that found considerable song intermediacy. Re-analysis of the Missouri data confirmed this difference. Correlation between an individual’s genetic composition and its song type was weak in Appalachian hybrid populations, and genetic introgression in both forms extended far beyond the limits of vocal admixture. Therefore, song is not a reliable indicator of levels of hybridization or genetic introgression at this contact zone. Varying ecological factors may play a role in producing variable levels of song admixture in different regions of the range interface.Una Evaluación de la Mixtura de Cantos como Indicador de Hibridación en Poecile atricapillus y P. carolinensis
Stable-Isotope (C, N, H) Analyses Help Locate the Winter Range of the Coastal Plain Swamp Sparrow (Melospiza Georgiana Nigrescens)
Authors: Greenberg Russell , Marra Peter P. , Wooller Matthew J. 
Published: September 2019

Abstract
Some taxa of North American birds have unknown winter ranges, because of the difficulty in tracking individuals between seasons. Stable isotopes may provide clues to help locate these nonbreeding populations. Previously, no valid records existed for the Coastal Plain Swamp Sparrow (Melospiza georgiana nigrescens) from October to late April. We used stable-isotope (C, N, and H) analyses to provide estimates of where molt occurs and then searched those areas for individuals of this species. The δ13C and δ15N of rump feathers were consistent with the Coastal Plain Swamp Sparrow molting in more saline marshes than the nominate subspecies after the breeding season, which confirms what was already known. The values for the same isotopes from crown feathers revealed that winter molt in the Coastal Plain Swamp Sparrow probably occurred in similar coastal brackish habitats. The δD of crown feathers indicated that prebreeding molt occurred at latitudes between South Carolina and Virginia. A subsequent search of this region located 18 Coastal Plain Swamp Sparrows, all of which were found in North Carolina or southeastern Virginia. Coastal Plain Swamp Sparrows were found predominantly in brackish marshes similar to their breeding habitat. On the basis of these observations, it appears that Coastal Plain Swamp Sparrows undergo a short southerly migration to a coastal region with substantially warmer winter conditions. This study is the first to make a specific geographic prediction based on stable-isotope analysis and to test the prediction in the field.
Análisis de Isótopos Estables (C, N, H) Ayudan a Localizar la Distribución Invernal de Melospiza georgiana nigrescens
Subcolony Variation in Breeding Success in the Tufted Puffin (Fratercula Cirrhata): Association With Foraging Ecology and Implications
Authors: Hipfner J. Mark , Charette Mathieu R. , Blackburn Gwylim S. 
Published: September 2019

AbstractLarge-scale oceanographic processes are the main drivers of seabird breeding success, but small-scale processes, though not as well understood, can also be important. We compared the success of Tufted Puffins (Fratercula cirrhata) breeding at two subcolonies only 1.5 km apart on Triangle Island, British Columbia, Canada, 2002–2005. In addition, we used stable-isotope analysis to test the hypothesis that parental foraging strategies differed between the two subcolonies, potentially underlying the variation in breeding success. Success was concordant across years at the two sites but, overall, Tufted Puffins bred more successfully at Strata Rock than at Puffin Rock. They raised chicks in all four years at Strata Rock, but in only three years at Puffin Rock; in two of those three years, Strata Rock chicks were, on average, 60 g and 100 g heavier than Puffin Rock chicks just before fledging. Discriminant analysis of carbon and nitrogen stable-isotope ratios in egg yolk and chick blood in 2004 and 2005 indicated that parental foraging differed between the two subcolonies, with both spatial (δ13C) and trophic-level (δ15N) differences involved. Thus, our study demonstrates the existence of foraging asymmetries in a pelagic seabird at a small spatial scale (between subcolonies), complementing patterns found at larger scales (between colonies). Moreover, the foraging asymmetries were associated with inequalities in fitness measures. We conclude that small-scale processes—in this case, systematic differences in the foraging ecology of local groups—can interact with large-scale oceanographic processes to determine seabird breeding success.Variation sous-coloniale du succès de reproduction de Fratercula cirrhata: Association avec l'écologie de la quête alimentaire et implications