bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spatial Responses of Bobolinks (Dolichonyx Oryzivorus) Near Different Types of Edges in Northern Iowa
Authors: Fletcher Robert J. , Koford Rolf R. 
Published: September 2019

Abstract
Habitat edges are well-studied components of fragmented landscapes, yet factors mediating edge effects remain unclear. We report how different types of edges surrounding patches may affect spatial distributions of Bobolink (Dolichonyx oryzivorus), a declining, area-sensitive songbird that breeds in grasslands. We expected Bobolinks to be less abundant near edges, and we investigated a set of alternative hypotheses for explaining that spatial pattern: (1) passive displacement, in which individuals do not avoid edges but use edges as boundaries for territories; (2) habitat gradients, in which individuals respond to habitat structure gradients near edges; (3) territory size, in which size of territories increases near edges; and (4) active avoidance, in which individuals actively avoid edges by positioning territory boundaries away from edges. To examine those hypotheses, we surveyed Bobolinks in grassland habitats near 34 edges of three different edge types (agriculture, road, and woodland) in northern Iowa, 1999–2000. Bobolink density was lower near woodland edges than near other edge types, and density increased as a function of distance from edge for all edge types. There was no evidence for a habitat gradient close to edges, but there was some evidence for habitat structure differing among edge types. Territory size increased near roads, decreased near woodlands, but did not change near agricultural edges. Territory positioning was consistent with active avoidance near woodland edges, and to a lesser extent road edges, but positioning was only consistent with passive displacement near agriculture edges. We conclude that land use surrounding patches can have variable effects on territorial dynamics and habitat use of this area-sensitive species. Linking edge avoidance with fitness is needed to understand the demographic consequences of those responses for species in fragmented landscapes.
Survival of Brown Boobies (Sula Leucogaster) at Johnston Atoll: A Long-Term Study
Authors: Beadell Jon S. , Schreiber E. A. , Schreiber Ralph W. , Schenk Gary A. , Doherty Paul F. 
Published: September 2019

AbstractSurvival of Brown Boobies (Sula leucogaster) at Johnston Atoll was examined over a 17-year period using capture-mark-recapture analysis. Annual adult survival was estimated to be 0.90 ± 0.01 (SE). Variation in survival did not correspond to either local environmental fluctuation or more widespread disturbances associated with El Niño-Southern Oscillation events, and a time-invariant model of survival was best supported by our data. Absence of major oceanographic anomalies in the immediate vicinity of Johnston Atoll may contribute to relatively high and invariant survival in Brown Boobies.
Recent Speciation in the Orchard Oriole Group: Divergence of Icterus Spurius Spurius and Icterus Spurius Fuertesi
Authors: Baker Jason M. , López-Medrano Esteban , Navarro-Sigüenza Adolfo G. , Rojas-Soto Octavio R. , Omland Kevin E. 
Published: September 2019

AbstractNew World orioles (Icterus) include several closely related species and subspecies pairs that provide excellent opportunities for studying recent speciation. We examined a subspecies pair in the Orchard Oriole group: Orchard Oriole (I. spurius spurius), a long-distance migrant that breeds in eastern North America, and Fuertes’s Oriole (I. s. fuertesi), a short-distance migrant that breeds in a restricted range in Veracruz, Mexico. We sequenced parts of the mitochondrial cytochrome-b gene (925 base pairs) and control region (344 base pairs) from 23 Orchard Orioles and 7 Fuertes’s Orioles. Subspecies are not reciprocally monophyletic. Instead, our data suggest that at least one taxon is paraphyletic or polyphyletic. We found little support for any further phylogenetic structure, including whether one subspecies might be derived from the other. However, haplotype frequency analysis suggests that there is little or no current gene flow between the taxa. The phylogenetic relationship between Orchard and Fuertes’s orioles is likely a result of recent divergence and incomplete lineage sorting. That interpretation is consistent with theoretical models of speciation, which predict patterns of nonmonophyly at early stages of taxon divergence. Our findings suggest that Orchard and Fuertes’s orioles are separate species and provide a case study for evaluating the importance of monophyly in defining species limits.
Dinosaurs of the Air: The Evolution and Loss of Flight in Dinosaurs and Birds
Authors: Feduccia Alan 
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 Seven-Year Comparison of Relative-Abundance and Distance-Sampling Methods
Authors: Norvell Russell E. , Howe Frank P. , Parrish Jimmie R. 
Published: September 2019

AbstractWe used data from statewide surveys of riparian birds in Utah, 1992–1998, to compare relative-abundance and distance-sampling methods. By generating relative-abundance indices with point-count methods and density with point-transect sampling methods, we examined whether the assumptions underlying each method were met during field surveys for four bird species (Brown-headed Cowbird [Molothrus ater], Bullock's Oriole [Icterus bullockii], Warbling Vireo [Vireo gilvus], and Yellow Warbler [Dendroica petechia]). Point-count methods failed to reasonably meet the fundamental assumption of constant proportionality, with estimated detectability varying 3- to 5-fold despite the use of widely accepted and well-standardized methods. Population trends based on relative abundance were subsequently unstable, often varying in both magnitude and direction with the survey plot radius used (25 m, 50 m, or unlimited distance). Distance-sampling methods appeared to meet critical assumptions, were robust to assumption violations, allowed methodological self-assessment, and were demonstrably efficient in a large-scale, multispecies survey setting. Our data show surveys of birds without estimations of detectability are likely biased because the assumption of constant proportionality is violated to a degree that precludes strict inference and may confound trend analyses.
Energy Allocation and Postnatal Growth in Captive Elegant Tern (Sterna Elegans) Chicks: Responses to High-Versus Low-Energy Diets
Authors: Dahdul Wasila M. , Horn Michael H. 
Published: September 2019

AbstractEffects of variable energy intake on chick growth, organ development, and gut-passage time in seabirds were investigated by raising Elegant Tern (Sterna elegans) chicks in the laboratory on three diets involving a major prey species, northern anchovy (Engraulis mordax), and a minor prey species, topsmelt (Atherinops affinis). Anchovies are ∼25% higher in energy content than topsmelt and represent a more abundant but highly fluctuating prey resource. Chicks were raised from age 15 to age 35 days posthatch on one of three diets (n = 8): (1) high-energy anchovy at the average daily intake rate, (2) low-energy topsmelt at the same intake rate, and (3) high-energy topsmelt (i.e. at a biomass equal in energy content to the anchovy diet). Chicks raised on the high-energy anchovy diet had a significantly faster gain of body mass and wing length. All three groups, however, had attained a statistically similar wing length at 35 days posthatch and did not differ in lean dry mass or pectoral muscle mass, indicating that energy was allocated preferentially toward wing development and flight capacity. Most digestive organs were heavier and gut-passage rates faster for chicks fed topsmelt. Bill dimensions and tarsus length showed little difference among chicks on the three diets. Lipid content of chicks that were fed anchovy was twice that of those fed low-energy topsmelt and one-third higher than that of chicks on the high-energy topsmelt diet. Our results indicate that Elegant Terns have evolved certain capacities for growth and digestion in response to variable prey quality that may increase the probability of chick survival. Nevertheless, if Elegant Tern chicks were switched to a lower quality, primarily topsmelt diet, they would be underweight at fledging with heavier digestive organs, lower lipid reserves, and faster gut-passage times, which would place added provisioning demands on the parents. Under that scenario, the prospects for survival and long-term reproductive success might diminish for such an Elegant Tern colony.
Novel Intron Phylogeny Supports Plumage Convergence in Orioles (Icterus)
Authors: Sanders Allen Eva , Omland Kevin E. 
Published: September 2019

AbstractA recent study of New World orioles (Icterus spp.), which traced a large number of plumage characters onto a mitochondrial DNA phylogeny, reported high frequencies of evolutionary convergence and reversal of plumage characters (Omland and Lanyon 2000). Although those results are consistent with other smaller scale studies that have documented plumage homoplasy, the mitochondrial genome is inherited as a single linkage group, so mitochondrial data represent only one gene tree. The mitochondrial (mt) DNA tree may not reflect the true evolutionary history of a lineage; therefore, it remains possible that the plumage characters could reflect the true species phylogeny. Other rapidly evolving regions of DNA can provide independent phylogenetic hypotheses useful for evaluating mitochondrial gene trees. A novel phylogenetic marker, a region of the nuclear gene ornithine decarboxylase (ODC) spanning from exon 6 to exon 8, was sequenced in 10 oriole species. The resultant nuclear gene tree reconstructs the same three major oriole clades as the mtDNA tree (Omland et al. 1999), supporting the conclusion that plumage evolution in the New World orioles has been highly homoplastic. Although most phylogenetic studies that have employed introns report greatest resolution at the genus or family level, ODC appears to offer some degree of phylogenetic resolution for infrageneric analyses. However, that intron has clearly not sorted to monophyly within or between closely related species.
Microsatellite Amplification From Museum Feather Samples: Effects of Fragment Size and Template Concentration on Genotyping Errors
Authors: Sefc Kristina M. , Payne Robert B. , Sorenson Michael D. 
Published: September 2019

AbstractWe address the problem of microsatellite genotyping errors associated with polymerase chain reaction (PCR) amplification from degraded and dilute template DNA and provide suggestions for improving the accuracy of genotype data in studies using older museum specimens as a source of DNA. In the course of a population genetics study of African indigobirds (Vidua spp.), we used replicate PCR to evaluate genotyping reliability for nine microsatellite loci in relation to PCR fragment length and DNA template concentration (DNA extracted from the calamus of one vs. two wing feathers). Complete amplification failure and the dropout of one allele from heterozygous genotypes were the predominant problems encountered. For samples with heterozygous genotypes, allele dropout occurred in 19.2 and 12.1% of PCR using extracts derived from one and two feathers, respectively. The amplification of artifact bands was less frequent (affecting 4.9 and 1% of positive PCR reactions with one- and two-feather extracts, respectively). Those results indicate that multiple replicates per sample and locus are required to obtain accurate genotype data from museum feather samples. Although higher DNA concentration improved success, PCR fragment size had a much stronger influence on the success and repeatability of microsatellite amplification, which suggests that the accuracy and efficiency of genotyping can be improved most easily by designing primers that amplify smaller DNA fragments.
Seasonal Patterns of Singing Activity Vary With Time of day in The Nightingale (Luscinia Megarhynchos)
Authors: Amrhein Valentin , Kunc Hansjoerg P. , Naguib Marc 
Published: September 2019

Abstract
Seasonal patterns of singing activity of male birds have been thoroughly studied, but little is known about how those patterns vary with time of day. Here, we censused mated and unmated male Nightingales (Luscinia megarhynchos) at four different hours of the day throughout the breeding cycle. In unmated males, singing activity increased until the young hatched in their neighborhood, and the seasonal variation was similar at each of the four hours of the day. In mated males, however, the seasonal patterns of singing activity differed between hours of the day. In morning (about the hour of egg-laying) and during the dusk chorus, the singing activity of mated males was strongly influenced by the females' reproductive state: singing activity was low before egg-laying and during incubation, but high during the egg-laying period. In the dawn chorus, however, singing activity showed a similar seasonal pattern in mated and unmated males and was high until late stages of the breeding cycle. Our results suggest that the social context influences singing behavior to a varying degree across the season, and that this variation also depends on time of day. The hour of data collection thus is an important but often neglected factor when seasonal changes of singing activity are studied.
A Nest Predator's View of a Managed Forest: Gray Jay (Perisoreus Canadensis) Movement Patterns in Response to Forest Edges
Authors: Ibarzabal Jacques , Desrochers André 
Published: September 2019

AbstractHigh nest-predation risk is often associated with forest edges. Most nest predators in boreal coniferous forests of North America are forest specialists living in mature stands. Nest predators have been studied mainly through use of artificial nests; knowledge of their behavior remains limited. We used radiotelemetry to examine movement patterns, relative to forest edge, of a forest nest predator, the Gray Jay (Perisoreus canadensis), in boreal coniferous forest. Each of 11 family groups of Gray Jays monitored in early summer exhibited a marked association with forest edges. Jays were found within 30 m of the forest edges more often than expected from random use of mature forest. Furthermore, jays traveled more slowly near forest edges than in the forest interior. Because forest edges apparently represent prime foraging habitat for Gray Jays, narrow forest strips left by logging could act as ecological traps for mature-stand songbirds before stands regenerate in adjacent clearcuts.
Interactive Communication Between Male and Female Great Tits (Parus Major) During the Dawn Chorus
Authors: Gorissen Leen , Eens Marcel 
Published: September 2019

Abstract
Studies of the dawn chorus in birds have focused mainly on the behavior and song output of males and on the function(s) of male song. Less attention has been paid to the females' behavior and to communication between members of a pair. In Great Tits (Parus major), males sing vigorously at dawn in the vicinity of the female's nest hole just before and during egg laying. We studied the female's vocal behavior during the dawn chorus as well as communication between pair members. All females vocally interacted with their mates from inside the nest box. Females produced a sound with a very low sound-pressure level only audible from few meters, which we have named the “quiet call.” This quiet call was unique to females and was only produced from inside the nest box. To our knowledge, our study is the first to show that both members of a pair vocally interact during the dawn chorus. Given that many temperate-zone bird species have similar life histories as the Great Tit, it is very likely that similar interactive behavior occurs in other (song)birds. This interactive behavior may provide a new and manipulable tool for testing hypotheses about the dawn song and can be used as a future bioassay of male vocalizations.
A New Species of Akalat (Sheppardia) Narrowly Endemic in the Eastern Arc of Tanzania
Authors: Beresford Pamela , Fjeldså Jon , Kiure Jacob 
Published: September 2019

AbstractThe group of small forest robins, or akalats, that dwell in lowland and montane forests in Africa have complicated parapatric or partly overlapping distributions, the details of which are still being discovered. Here, we use external morphology and mitochondrial and nuclear DNA sequence data to determine the reciprocal monophyly of several populations, including one form that is related to Sheppardia lowei and S. montana. Those data corroborate the recognition of a new species, Sheppardia aurantiithorax, and show relatively high levels of sequence divergence among populations of the different species. The discovery of this new species, narrowly endemic in the Eastern Arc montane forests, emphasizes the complex biodiversity of the region and underscores the need for prompt and effective conservation measures.
Phylogenetic Relationships Among Some Neotropical Parrot Genera (Psittacidae) Based on Mitochondrial Sequences
Authors: Tavares Erika S. , Yamashita Carlos , Miyaki Cristina Y. 
Published: September 2019

Abstract
The New World tribe Arini includes 30 genera and represents 148 known species of parrots. A previous phylogenetic study examined nine of those genera and suggested the existence of two groups. Our objective was to better understand the relationships among 14 species from 9 genera belonging to one of those groups. We partially sequenced the 12S and 16S ribosomal DNAs, cytochrome b, cytochrome oxidase I, and control region. We improved our understanding of the phylogenetic relationships among Neotropical parrots by adding both taxa and sequences, but the relationships among the deeper lineages were not well resolved. Our results agree with present classifications that place some species formerly in the genus Ara into three additional genera (Primolius, Orthopsittaca, and Diopsittaca). Additionally, we suggest that (1) D. nobilis and Guarouba guarouba are closely related and the genus Aratinga is not monophyletic; (2) diversification of genera may have occurred during the Miocene, and of species within genera during the Pliocene and Pleistocene; and (3) geologic, climatic, and environmental changes in South America may have been related to that diversification.
Is Monogamy in the Polynesian Megapode (Megapodius Pritchardii) Related to its High Relative Egg-Weight?
Authors: Göth Ann , Vogel Uwe 
Published: September 2019

AbstractParental care is regarded as one of the most influential forces acting on the evolution of mating systems. Polynesian Megapodes (Megapodius pritchardii) are burrow nesters and rely on geothermal heat for incubation. Because they provide no parental care, either before or after hatching, they can provide insights into selective forces that have shaped mating systems in the absence of parental care. Our study of their mating system—the first such study of any burrow-nesting megapode—suggests social monogamy. The partners of 10 marked pairs stayed together in the same territory for ≤12 months and were seen with their partner significantly more often than on their own. In 64% of all observations, pair partners foraged <5 m apart, and females fed on food items uncovered by the male. Duets also indicated long-lasting pair bonds. We propose that monogamy in this species is related to the fact that females lay only one large egg at a time (which weighs, on average, 24% of her body weight), in intervals of several days or weeks. Producing eggs year-round, females require a high intake of protein-rich food. They seem to benefit, within the pair bond, from the male-defended feeding territory and from the invertebrates the male uncovers while feeding close by. While being guarded by the male, females can spend more time searching for food and are protected from forced copulations by other males. The monogamous pair bond seems to benefit the male by enhancing his chances of fertilizing his partner's eggs; with an unpredictable laying interval and year-round egg production, males cannot predict when their partner will be fertile and thus benefit from staying with her year-round.
Use of Body Stores in Shorebirds After Arrival on High-Arctic Breeding Grounds
Authors: Morrison R. I Guy , Hobson Keith A. 
Published: September 2019

AbstractStable-isotope analyses of egg components can illuminate the contributions of endogenous and exogenous nutrients to egg formation in cases where birds move from one isotopic biome to another just before egg-laying, as in Red Knots (Calidris canutus islandica) and Ruddy Turnstones (Arenaria interpres interpres) nesting in the northeastern Canadian High Arctic. Those populations use inshore marine habitats during the winter and northward migration periods, but switch to feeding and breeding in terrestrial C-3 habitats in the Arctic. Upon the birds' arrival at Alert, Nunavut, Canada, stable carbon (δ13C) and nitrogen (δ15N) isotope values for their red blood cells were consistent with those expected from an inshore marine diet. After the birds switched to a terrestrial diet, those values decayed in a negative exponential fashion until they reached asymptotic values consistent with a local terrestrial C-3 diet. Components of eggs laid later in the season, including lipid-free yolk, albumen, yolk lipid, and albumen lipid, generally showed isotope values consistent with routing from exogenous (i.e. local) nutrient sources, which supports the notion that High Arctic shorebirds are primarily income and not capital breeders. However, eggs in earliest clutches were enriched in 13C and 15N, which suggests that some residual marine nutrients were available for reproduction. The extent to which endogenous stores are transferred to eggs in High Arctic shorebirds may depend on year and climatic conditions.
Flushing, Capture, and Bleeding do not Affect Return Rate of Female Wood Thrushes (Hylocichla Mustelina) in Delaware
Authors: Perkins Kelly A. , Roth Roland R. , Bowman Jacob L. , Green Jordan 
Published: September 2019

Abstract
Theoretical questions and conservation concerns have prompted numerous, intensive studies of songbird nesting ecology. Such studies use several techniques (flushing, capture, and blood sampling) that have the potential to negatively affect reproduction, survival, and site fidelity. Although studies have examined the effects of those techniques on avian reproduction and survival, the effect on the return rate of breeding songbirds has not been researched. We used data from a 28-year demographic study to investigate the possible effect of those three common research practices on the return rate of female Wood Thrushes (Hylocichla mustelina). We also tested reproductive success and age as predictors of return because they have been shown to influence site fidelity. Number of successful nests in a breeding season was the variable that best predicted return the following year. None of the research practices negatively affected return rate. That pattern held even among yearlings with zero production, a group that should be the most easily disturbed. We also show that using all years of return for site-faithful birds as observations (i.e. repeated sampling) inflates the estimated return rate.