bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phylogenetic Position and Generic Placement of The Socorro Wren (Thryomanes Sissonii)
Authors: Gómez Juan E. Martínez , Barber Brian R. , Peterson A. Townsend 
Published: September 2019

AbstractSince early in its taxonomic history, placement of the Socorro Wren (Thryomanes sissonii) has been an object of contention. Of particular interest is its current placement in the genus Thryomanes, which makes that genus ditypic and leads to an odd biogeographic scenario for the Socorro Wren's colonization of Socorro Island. We assessed its phylogenetic position by analyzing 516 base pairs of mitochondrial DNA sequences from the ND2 gene of this species and 14 additional wren taxa. Contrary to its present placement, the Socorro Wren is nested phylogenetically within the House Wren species complex, being placed as sister to the clade Troglodytes aedon + T. musculus. The current hypothesis (i.e. sister to Thryomanes bewickii) is strongly invalidated by our analysis. Our analyses indicate that the most appropriate taxonomic classification for the Socorro Wren is Troglodytes sissonii.Posición Filogenética y Ubicación Genérica de Thryomanes sissonii
Sexual Preferences of Female Brown-Headed Cowbirds (Molothrus Ater) for Perched Song Repertoires
Authors: Hosoi S. Aki , Rothstein Stephen I. , O'Loghlen Adrian L. 
Published: September 2019

AbstractThe importance of repertoire size to mate choice by female songbirds has been widely debated but has not been addressed in Brown-headed Cowbirds (Molothrus ater; hereafter ”cowbirds”), despite extensive work on this species' songs. Male cowbirds cycle through repertoires of 2–8 perched song (PS) types in rapid sequences immediately prior to and during copulation, which suggests that repertoire size or content is important in mating contexts. Because male mating success in one well-studied cowbird population is correlated with large PS repertoires, we predicted that repertoire size is a cue in female mate choice. To test that prediction, we played three repetitions of conspecific songs in rapid succession to estradiol-primed female cowbirds (M. a. obscurus), to simulate the rapid song sequences that accompany naturally occurring matings. Females were presented with three different PS types, three repetitions of the same type, and heterospecific control songs of the same duration as the conspecific playbacks. Females gave longer copulation solicitation displays to three different PS types than to three repetitions of a single PS type, regardless of whether the playback songs were local or foreign. This is one of the few experimental studies on songbirds to show greater female responsiveness to a song repertoire presented so as to mimic singing in a natural mating context, and the first to present such a result for cowbirds. We conclude that presentation of multiple PS types is more sexually stimulating to females than a single type, because females prefer larger repertoires or singing patterns with a higher frequency of song-type switching.Preferencias Sexuales de Hembras de Molothrus ater por Repertorios de Canto de Percha
Concordance Between Morphological and Molecular Markers in Assessing Hybridization Between Sharp-Tailed Sparrows in New England
Authors: Shriver W. Gregory , Gibbs James P. , Vickery Peter D. , Gibbs H. Lisle , Hodgman Thomas P. , Jones Peter T. , Jacques Christopher N. 
Published: September 2019

AbstractHybridization is pivotal in framing ideas about species concepts and has the potential to produce novel genotypes that may serve as starting points for new evolutionary trajectories. Presently, Nelson’s Sharp-tailed Sparrows (Ammodramus nelsoni subvirgatus) and Saltmarsh Sharp-tailed Sparrows (A. caudacutus caudacutus) are in contact in salt marshes of Maine, New Hampshire, and northern Massachusetts. These two species hybridize, but the extent and direction of introgression has not been determined. We assessed morphological and genetic variation of 123 sharp-tailed sparrows from 5 salt marshes in New England. We used six morphological variables, including a plumage-scoring index, and five mic-rosatellite primers to assess the extent of introgression and to determine whether there was concordance between phenotypic and genotypic variation. We identified apparent hybrids and each of the two sharp-tailed sparrow species using a plumagescoring index. In general, we found that hybrids were more similar morphologically and genetically to Saltmarsh Sharp-tailed Sparrows. The alleles of hybrids were 62% Saltmarsh and 38% Nelson’s Sharp-tailed Sparrows, supporting the asymmetrical hybridization hypothesis.Concordancia entre Marcadores Morfológicos y Moleculares al Evaluar la Hibridación entre Ammodramus nelsoni subvirgatus y A. caudacutus caudacutus en Nueva Inglaterra
Scytalopus Stilesi, A New Species of Tapaculo (Rhinocryptidae) From the Cordillera Central of Colombia
Authors: Cuervo Andrés M. , Cadena Carlos Daniel , Krabbe Niels , Renjifo Luis Miguel 
Published: September 2019

AbstractWe describe Scytalopus stilesi, an overlooked species of tapaculo endemic to Colombia, on the basis of a series of eight specimens taken in 2002 and comparative analyses of its vocalizations, mitochondrial DNA sequences, and distribution. The new species ranges in the northern half of the Cordillera Central of the Colombian Andes in the Departments of Antioquia, Caldas, and Risaralda, in cloud forests between 1,420 and 2,130 m above sea level. The song, calls, and female song of the new species differ distinctly from those of all other known Scytalopus taxa. Phylogenetic analyses based on sequences of the cytochrome-b gene strongly suggest affinities with S. robbinsi of southwestern Ecuador and with two as-yet-undescribed tapaculos from the Colombian Andes. Scytalopus stilesi coexists locally with, though it is ecologically segregated from, S. atratus, S. latrans, and S. spillmanni. The mid-elevation premontane wet forests to which the new species is restricted have been subject to severe deforestation and fragmentation. The species is, however, relatively common in continuous mature-forest remnants, large primary-forest fragments, riparian forests, and tall secondary-forest patches. We employed a geographic information system (GIS) approach to model the potential distribution of the new species and assess its conservation status under the International Union for the Conservation of Nature (IUCN) criteria. Scytalopus stilesi does not qualify as threatened according to those criteria, but it should be regarded as near threatened. The new species coexists with numerous threatened bird species that are in need of more effective conservation.
Cerulean Warbler (Dendroica Cerulea) Microhabitat and Landscape-Level Habitat Characteristics in Southern West Virginia
Authors: Weakland Cathy A. , Wood Petra Bohall 
Published: September 2019

AbstractThe Cerulean Warbler (Dendroica cerulea) is a species of conservation concern in eastern North America, where declines in its population have been documented over the past several decades. A high proportion of the population occurs in forested areas of southern West Virginia, where it may be threatened by loss and degradation of forested habitat from mountaintop mining and valley fill (MTMVF). We examined, from a landscape perspective, the effects of forest fragmentation (in particular, effects of fragment size and response to edges) on Cerulean Warblers, using territory mapping techniques and geographic information system (GIS) technology in portions of four counties in southwestern West Virginia. We quantified landscape characteristics from digitized aerial photographs and measured microhabitat characteristics on spot-mapping plots. Territory density of Cerulean Warblers was 4.6 territories per 10 ha in intact forest and 0.7 territories per 10 ha in fragmented forest. The best habitat model included both landscape and microhabitat variables and indicated that territory density increased with increasing snag density, percentage of canopy cover >6–12 m and >24 m in height, and distance from mine edge. Models for predicting microhabitat use at the territory level were weak, indicating that microhabitat characteristics of territories were similar to habitat available on spot-mapping plots. The species did not appear to avoid internal edges, such as natural canopy gaps and open-canopy or partially open-canopy roads. Territory placement on ridges was greater than expected, and in bottomlands (ravines) and midslopes less than expected, given availability. Fifty percent of all territories were on ridges. Preference for ridges suggests that MTMVF may have a greater effect on Cerulean Warbler populations than other sources of forest fragmentation, given that ridges are removed in MTMVF. Our data indicate that Cerulean Warblers are negatively affected by mountaintop mining from loss of forested habitat, particularly ridgetops, and from degradation of remaining forests, as evidenced by lower territory density in fragmented forests and lower territory density closer to mine edges.
Laying Plasticity in an Avian Brood Parasite
Authors: Forman Dan W. 
Published: September 2019

AbstractFemales of some bird species “steal“ the parental care of other breeding individuals by laying eggs parasitically in their nests. In most populations, conspecific brood parasites lay parasitically before laying in their own nests. By contrast, in a young and expanding Common Moorhen (Gallinula chloropus) population, 17.4% (n = 8) of brood parasites laid parasitically when their own clutches were currently being incubated, and 13.1% (n = 6) laid parasitically when they were tending to their young. This result differs from previous data on conspecific brood parasitism in this (and other) avian species and suggests that sitespecific ecological conditions exert differing selective influences on the behavioral development of populations. The behavior adopted by individual vertebrate species may not, therefore, be rigidly fixed throughout their geographic range.
Effects of Weather and Population Density on Reproductive Success and Population Dynamics in a Song Sparrow (Melospiza Melodia) Population: A Long-Term Study
Authors: Chase Mary K. , Nur Nadav , Geupel Geoffrey R. 
Published: September 2019

AbstractWe studied the relationships among weather, reproductive success, and population density over 21 years (1980-2000) in a resident Song Sparrow (Melospiza melodia) population in coastal scrub habitat. Our goals were to test potential relationships between annual variation in weather and reproductive success, to evaluate whether reproductive success is density dependent, and to explore the effects of weather and population density on population dynamics. We analyzed the following components of reproductive success: clutch size, hatching success, fledging success, number of young fledged per successful nest, nestling weight, number of fledglings produced per female, number of broods per female, and probability of nest survival. During the study period, several very wet El Niño-Southern Oscillation (ENSO) events as well as an eight-year period of below-average rainfall occurred. Annual reproductive success and population density showed strong positive relationships to annual rainfall levels. Song Sparrow reproductive success increased with increasing rainfall and peaked at above-average rainfall levels. However, no component of reproductive success was related to an index of variation in the ENSO (i.e. Southern Oscillation Index). The components of reproductive success most strongly associated with rainfall were probability of nest survival and length of the breeding season. Nest predation rates were lower in wetter years. Song Sparrows nested over a longer period in years with higher rainfall and lower summer temperatures, and there was an increase in the number of successful broods per female in wetter, cooler years. Nestling weight was not associated with annual rainfall. Neither clutch size nor the onset of laying was associated with spring temperatures. Warmer summer temperatures were associated with a decrease in number of young fledged per successful nest. We found no evidence for decreased reproductive success in years of higher population density, which suggests that reproductive success was limited primarily by density-independent factors, such as weather. Changes in population density from one year to the next were positively related to rainfall-associated variation in reproductive success and negatively related to population density in the previous year. Rainfall in the previous year explained at least 49% of the annual variation in population density. Thus, population dynamics appeared to be driven both by density-independent and density-dependent factors.
Homing Success of Migrant Versus Nonmigrant Dark-Eyed Juncos (Junco Hyemalis)
Authors: Keiser Jeffrey T. , Ziegenfus Charles W. S. , Cristol Daniel A. 
Published: September 2019

AbstractWithin a population, the evolution of migratory behavior is accompanied by a suite of physiological, behavioral, and cognitive adaptations. Spatial memory is associated with the hippocampus in mammals and birds; in some cases, hippocampal neuroanatomy correlates with differences in behavior. In a recent study, a migratory subspecies of sparrow, the Dark-eyed Junco (Junco hyemalis hyemalis), performed better on room-scale spatial memory tests than did a nonmigratory conspecific. Migrants collected after migration also possessed greater hippocampal neuron density, which suggests a neurological basis for differences in spatial memory and a link between migratory behavior and enhanced spatial memory. It is likely that homing behavior, like migration, relies to some extent on spatial memory. In some instances, spatial memory performance has generalized across spatial scales, with pronounced differences at larger scales. We tested whether differences in spatial memory between migrants and nonmigrants, previously observed at a room scale, were detectable at a landscape scale; specifically, we investigated whether differences in homing ability could be detected after displacements of 1–40 km. We found no difference in number of returning individuals or in duration of return. Our results suggest that homing in this species may not rely on aspects of spatial memory that differed in aviary tests.
Edge Avoidance by Nesting Grassland Birds: A Futile Strategy in a Fragmented Landscape
Authors: Renfrew Rosalind B. , Ribic Christine A. , Nack Jamie L. 
Published: September 2019

Abstract
Some grassland passerine species are considered area-sensitive, but the mechanisms underlying that phenomenon are not understood, particularly on grazed grasslands. Area sensitivity may result from edge avoidance or higher nest predation near edges, both of which may be influenced by predator activity or cattle-induced vegetational differences between pasture edge and interior. We assessed the effect of distance to edge on nest density and predation Savannah Sparrows (Passerculus sandwichensis), Grasshopper Sparrows (Ammodramus savannarum), Bobolinks (Dolichonyx oryzivorus), and meadowlarks (Sturnella spp.) along wooded and nonwooded edges of Wisconsin pastures in 1998-2000 and the activity of potential mammalian nest predators along those edges in 2000-2001. We found a positive relationship between nest density and distance from edge for all edge types combined, but that was not the result of effects of wooded edges: we found no difference in density between nests located <50 or <100 m from wooded versus nonwooded (crop or grassland) edges. Models that included combinations of vegetation structure (e.g. concealment), initiation date, year, or edge variables (or all four) were poor predictors of the probability of nest predation. Placing nests away from edges, therefore, did not reduce the risk of nest predation. Eight species known to prey on grassland bird nests were documented along pasture edges, raccoon (Procyon lotor) being the most common. Frequency of raccoon and thirteen-lined ground squirrel (Spermophilus tridecemlineatus) visitation was higher along wooded edges and nonwooded edges, respectively. Cattle (Bos taurus) activity did not differentially affect vegetation height-density along edges compared with that in the pasture interior. Possible reasons for predation risk being similar in both pasture interiors and edges in a fragmented landscape include the ease with which predators can move within pastures, high percentage of resident grassland predators, and small size (median = 47.2 ha) of pastures.
Geographic Variation in Brown-Headed Cowbird (Molothrus Ater) Parasitism on Dickcissels (Spiza Americana) in Great Plains Tallgrass Prairie
Authors: Jensen William E. , Cully Jack F. 
Published: September 2019

AbstractThe incidence of brood parasitism by Brown-headed Cowbirds (Molothrus ater; hereafter “cowbirds“) within host species typically reflects the continental pattern in cowbird abundance across North America, where parasitism is heaviest in the Great Plains. However, we found considerable variation in cowbird parasitism on Dickcissel (Spiza americana) nests within a subregion of the Great Plains (the Flint Hills), where the highest levels of cowbird parasitism on grassland bird nests had been previously reported. Local parasitism frequencies on Dickcissel nests varied latitudinally across the Flint Hills, ranging from 0% to 92% of nests parasitized. Interestingly, we found no obvious patterns in habitat or host attributes that were associated with this steep geographic gradient in brood parasitism. Cowbird parasitism on Dickcissel nests was not correlated with the vertical density of local prairie vegetation, mean nest distance to edge, proportion of forest to grassland habitat surrounding study sites (≤5 to 10 km), geographic variation in host abundance, or Dickcissel density or nest initiation dates. Parasitism frequencies and intensities (number of cowbird eggs per parasitized nest) on Dickissel nests were only significantly related to variation in local female cowbird density. Dickcissel clutch size and apparent fledging success were negatively correlated with local cowbird parasitism levels. Geographic patterns in cowbird abundance within and among regions should be considered when establishing conservation areas for grassland birds or other cowbird hosts of concern.
Time-Specific Variation in Passerine Nest Survival: New Insights into Old Questions
Authors: Grant Todd A. , Shaffer Terry L. , Madden Elizabeth M. , Pietz Pamela J. 
Published: September 2019

AbstractUnderstanding nest survival is critical to bird conservation and to studies of avian life history. Nest survival likely varies with nest age and date, but until recently researchers had only limited tools to efficiently address those sources of variability. Beginning with Mayfield (1961), many researchers have averaged survival rates within time-specific categories (e.g. egg and nestling stages; early and late nesting dates). However, Mayfield’s estimator assumes constant survival within categories, and violations of that assumption can lead to biased estimates. We used the logistic-exposure method to examine nest survival as a function of nest age and date in Clay-colored Sparrows (Spizella pallida) and Vesper Sparrows (Pooecetes gramineus) breeding in north-central North Dakota. Daily survival rates increased during egg laying, decreased during incubation to a low shortly after hatch, and then increased during brood rearing in both species. Variation in survival with nest age suggests that traditional categorical averaging using Mayfield’s or similar methods would have been inappropriate for this study; similar variation may bias results of other studies. Nest survival also varied with date. For both species, survival was high during the peak of nest initiations in late May and early June and declined throughout the remainder of the nesting season. On the basis of our results, we encourage researchers to consider models of nest survival that involve continuous time-specific explanatory variables (e.g. nest age or date). We also encourage researchers to document nest age as precisely as possible (e.g. by candling eggs) to facilitate age-specific analyses. Models of nest survival that incorporate time-specific information may provide insights that are unavailable from averaged data. Determining time-specific patterns in nest survival may improve our understanding of predator-prey interactions, evolution of avian life histories, and aspects of population dynamics that are critical to bird conservation.
The Howard and Moore Complete Checklist of the Birds of the World
Authors: Kratter Andrew W. 
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 refl ect the opinions of the editors or any offi cial policy of the American Ornithologists' Union.
Reproductive Success Across The Black-Capped Chickadee (Poecile Atricapillus) and Carolina Chickadee (P. Carolinensis) Hybrid Zone in Ohio
Authors: Bronson C. L. , Grubb Thomas C. , Sattler Gene D. , Braun Michael J. 
Published: September 2019

AbstractBlack-capped Chickadees (Poecile atricapillus) and Carolina Chickadees (P. carolinensis) hybridize in an east-west band from New Jersey to Kansas. Within the past century, the Ohio portion of this hybrid zone and the Carolina Chickadee range to the south have been moving northward, whereas the Black-capped Chickadee range has retracted. In Ohio, we characterized the genetic composition of the hybrid zone using five diagnostic molecular loci. Although there was no evidence of assortative mating in the center of the hybrid zone, we found a relative paucity of genetically intermediate breeding females as compared with breeding males. That suggests viability selection against female hybrids, in line with Haldane’s rule. On the basis of reproductive variables (number of nestlings, reproductive success), we found a decrease in productivity of breeding pairs in the hybrid zone that is significantly and positively related to their probability of producing homozygous offspring at each autosomal or sex-linked locus. We also found that the decrease in productivity was significantly and positively related to the genetic composition of the male of the pair (i.e. pure male chickadees more productive). These data strongly suggest that hybrids are at a selective disadvantage. Because the zone of reduced reproductive success was considerably narrower than the zone of introgression, our results demonstrate that genetic introgression is occurring in the face of substantial selection against hybrids.Éxito Reproductivo a través de la Zona de Hibridación de Poecile atricapillus y P. carolinensis en Ohio