bluuebunny/crossref_metadata_2025_split huggingface dataset:
Protogyny in Autumn Migration: Do Male Birds ”Play Chicken”?
Authors: Mills Alexander M. 
Published: September 2019

AbstractProtandry, the earlier arrival of males than of females on breeding areas, occurs in many taxa, including many migratory birds. Numerous hypotheses have been generated to explain protandry. Using bird-banding records, I show that protogyny, the earlier migration of females, frequently occurs in the autumn, though it is less universal and less dramatic than spring protandry. In one species, it occurs in both hatch-year and adult birds. When (1) spring and autumn, (2) departures and arrivals, and (3) breeding and wintering ground conditions are considered, hypotheses generated only to explain spring protandry can be more thoroughly evaluated. Using that approach, the most parsimonious explanation of differential migration between the sexes explains earlier male arrival in spring and later male departure in autumn through either (1) indirect selection operating on intrasexual male competition for territories or (2) direct selection operating on intersexual relations requiring males to be present on breeding territories when females are present. In autumn-protogynous species, males may ”play chicken,” balancing the benefits of remaining longer than females and protecting territories for subsequent years against the costs of remaining in the north under deteriorating conditions and delaying the acquisition of a good winter territory.Protogynie et migration automnale: Est-ce que les mâles ”jouent les dégonflés”?
Mitochondrial Variation in Bolivian Populations of the Variable Antshrike (Thamnophilus Caerulescens)
Authors: Brumfield Robb T. 
Published: September 2019

AbstractThe Variable Antshrike (Thamnophilus caerulescens) is arguably the most polytypic thamnophilid, with males ranging from almost entirely jet black to nearly white. The four subspecies that occur in Bolivia are strikingly divergent in male plumage: T. c. aspersiventer (black with white-barred belly), T. c. connectens (black back and bib with white belly), T. c. dinellii (gray throat and back with rufous belly), and T. c. paraguayensis (light gray with white belly). To assess the genetic structure of those taxa in Bolivia, sequence variation at the mitochondrial cytochrome-b gene was screened in 126 individuals collected across transects spanning the plumage and vocal variation in the four forms. A 95-km-wide cline in haplotype frequencies from T. c. aspersiventer to T. c. dinellii was centered in the Serrania Cochabamba across an ecotone from humid to dry Andean foothill habitats. Thamnophilus caerulescens connectens is not a valid taxon, instead representing an introgressed population near the dinellii tail of the T. c. aspersiventer-T. c. dinellii hybrid zone. Although direct contact between T. c. dinellii and T. c. paraguayensis remains undocumented, the mitochondrial data were consistent with introgression along a broad cline extending across most of southern Bolivia. Overall, the transitions in mitochondrial frequencies were remarkably concordant with clinal changes in vocalizations among those same populations (Isler et al. 2005). Both studies highlight the need for increased sampling, in both the geographic extent and number of individuals per population, to address adequately the potential for clinal variation between populations that are not isolated geographically. A more restricted sampling design in the present study might have led to the erroneous conclusion that T. c. aspersiventer, T. c. dinellii, and T. c. paraguayensis have reciprocally monphyletic mitochondrial lineages, making them full species according to some species concepts.
Burrowing Owl (Athene Cunicularia) Population Genetics: A Comparison of North American Forms and Migratory Habits
Authors: Korfanta Nicole M. , McDonald David B. , Glenn Travis C. 
Published: September 2019

AbstractWe assessed the effects of range disjunction, migratory habit, coloniality, and habitat structure on the genetic differentiation of North American Burrowing Owl (Athene cunicularia) populations. Burrowing Owls in North America comprise two forms or subspecies: A. c. floridana in Florida, separated by ∼1,500 km from the western form, A. c. hypugaea, which ranges from Texas to California and north to southern Canada. Burrowing Owls tend to be loosely colonial, and both the Florida populations and southerly populations of A. c. hypugaea from California to Texas are nonmigratory. To assess genetic structure, we examined 201 individuals from nine western and six Florida populations at seven highly variable microsatellite DNA loci. Mean gene diversity (Hexp) was higher in the west than in Florida (0.539 and 0.341, respectively; P < 0.05). Populations within subspecies were essentially panmictic (A. c. floridana: θ = 0.038, ρ = 0.014; A. c. hypugaea: θ = 0.014, ρ = 0.009) and even genetic differentiation across subspecies was modest (θ = 0.051, ρ = 0.014). Nevertheless, the western and Florida forms were easily distinguished by any of several criteria, such as allelic absences in Florida, assignment tests, and well-supported branches on the inferred phylogenetic tree. Genetic differentiation was at least twice as great in resident Florida (θ = 0.038) and California (θ = 0.021) populations as in migratory western populations (θ = 0.012), though 95% confidence intervals of theta estimates overlapped. We found no evidence of a genetic bottleneck that would result in evolutionary disequilibrium within subspecies. In the west, high observed heterozygosity values and evidence of gene flow suggest that population declines and patchy habitat, which currently imperil this species throughout much of its range, have not led to inbreeding or biologically meaningful genetic differentiation among the sampled populations.
Survival of Young Greater Snow Geese (Chen Caerulescens Atlantica) During Fall Migration
Authors: Menu Stéphane , Gauthier Gilles , Reed Austin 
Published: September 2019

AbstractThe many hazards that await birds along their migratory routes may negatively affect their survival, especially among newly fledged young. We estimated survival of young Greater Snow Geese (Chen caerulescens atlantica) during fall migration from the High Arctic to temperate areas and examined factors affecting their survival over a five-year period, using two approaches. First, each year (1993–1997), we banded fledglings and adults in mid-August, just before their departure from Bylot Island in the High Arctic (Nunavut, Canada), and again at an important staging area 3,000 km to the south at the Cap Tourmente National Wildlife Area (Québec, Canada) in October; recovery data from those two banding periods allowed estimation of survival during fall migration. Second, we visually determined brood size of neck-banded females before and after the main portion of the migratory flight, to estimate survival of young. The two approaches yielded similar survival estimates and showed the same interannual variation, thus suggesting that estimates were reliable. Mortality of young shortly after fledging and during the fall migration was high, compared with that of adults (monthly survival 0.662 in young vs. 0.989 in adults). However, mortality of young after migration was similar to that of adults (monthly survival 0.969 in young vs. 0.972 in adults). Migration survival of young varied considerably among annual cohorts (range of 0.119–0.707 over five years), and most of the mortality appeared to be natural. Survival was especially low in years when (1) temperatures at time of fledging and start of migration were low (i.e. near or below freezing), (2) mean body mass of goslings near fledging was low, or (3) mean fledging date was late. Our results suggest that migration survival of young is affected by a combination of several factors (climatic conditions, body mass, and fledging date) and that survival is reduced when one of those factors intervenes.
Effects of Environmental Conditions and Parental Quality on Inter- and Intraclutch Egg-Size Variation in the Collared Flycatcher (Ficedula Albicollis)
Authors: Hargitai Rita , Török János , Tóth László , Hegyi Gergely , Rosivall Balázs , Szigeti Beáta , Szöllősi Eszter 
Published: September 2019

AbstractEgg size is a particularly important life-history trait mediating maternal influences on offspring phenotype. Females can vary their egg-size investment in relation to environmental circumstances, their own breeding condition, and the quality of their mate. Here we analyzed inter- and intraclutch variation in egg size in the Collared Flycatcher (Ficedula albicollis) on the basis of eight years of data. According to our results, mean egg size increased with female condition, but did not differ among young, middle-aged, and old females. The male’s age, body size, and forehead patch size did not influence egg size; thus, we found no evidence for differential investment in egg size in relation to male quality. We found no effect of laying date on egg size when controlling for ambient temperature during the egg formation period, yet temperature had a significant effect on egg size. That result indicates proximate constraints on egg formation. Furthermore, we report on annual differences in intraclutch egg-size variation. Egg size increased within clutches in years with a warm prelaying period; whereas in years when the weather during that period was cold, there was no significant intraclutch trend. Proximate considerations seem to explain the observed patterns of intraclutch egg-size variation; however, we cannot reject the adaptive explanation. Mean egg size and intraclutch egg-size variation were unrelated to clutch size. Therefore, we found no evidence for a trade-off between size and number of eggs within a clutch.
Effects of Water Salinity on Growth and Survival of Common Eider (Somateria Mollissima) Ducklings
Authors: DeVink Jean-Michel A. , Gilchrist H. Grant , Diamond Antony W. 
Published: September 2019

AbstractThe need for fresh water may affect growth and survival of young waterfowl, including ducklings of sea ducks that are routinely raised in coastal marine habitats. We studied the influence of water salinity on growth and survival of Common Eider (Somateria mollissima) ducklings collected from nests on Southampton Island, Nunavut, Canada, in July 2001 and 2002. In 2001, 50 ducklings were partitioned into five groups (n = 10) and assigned a water salinity treatment for 6.5 days. Treatments included fresh water (<1 ppt NaCl), brackish water (11 ppt or 21 ppt), seawater (33 ppt), and a mixed regime (<1 ppt for 12 h, followed by 33 ppt for six days). In 2002, the experiment was replicated twice with different ducklings. Overall, growth rates were negatively correlated, and mortality rates positively correlated, with water salinity: 3%, 17%, and 60% of ducklings died in the <1-ppt, 11-ppt, and 21-ppt treatment groups, respectively; and 100% died in the 33-ppt and mixed-regime groups. The results confirm that fresh water is required for growth and survival of Common Eider ducklings immediately after hatch, which suggests that sources of fresh water in brood-rearing areas are an important requirement for successful reproduction.
Host Recognition of Brood Parasites: Implications for Methodology in Studies of Enemy Recognition
Authors: Grim Tomáš 
Published: September 2019

AbstractVarious studies have shown that experiments on nest defense and enemy recognition (e.g. recognition of adult brood parasites) can be confounded by many factors. However, no study has described a confounding effect of control dummy type. Here, I show experimentally that the choice of control dummy may influence the results of an experiment and lead to erroneous conclusions. I tested recognition abilities of the Blackcap (Sylvia atricapilla), currently a host rarely used by the Common Cuckoo (Cuculus canorus). Blackcaps responded very differently to two kinds of control dummies: they ignored the Eurasian Blackbird (Turdus merula) dummy, but attacked the Rock Pigeon (Columba livia) dummy as frequently as they attacked the Common Cuckoo. The differing results may be explained by the fact that the Rock Pigeon is more similar to the Common Cuckoo than the Eurasian Blackbird is, and consequently elicited more aggressive behavior than the latter. Thus, absence of discrimination in enemy-recognition studies may reflect a methodological artifact resulting from varying abilities of particular hosts to discriminate along a continuum of recognition cues. This result has serious methodological implications for further research on enemy recognition and aggression in general: a control dummy should not be too similar to the dummy brood parasite; otherwise, the chance of detecting existing recognition abilities is low. Further, I argue that coevolution only increases pre-existing aggression in the particular host species. Therefore, increment analysis (assessing changes in host antiparasitic responses during the nesting cycle while controlling for background aggression to control dummies) provides a more accurate picture of hosts' recognition abilities than the traditional approach (when the total level of antiparasitic response is analyzed).
Fat-Deposition Strategies Among High-Latitude Passerine Migrants
Authors: Benson Anna-Marie , Winker Kevin 
Published: September 2019

AbstractWe studied fat stores in passerine migrants at a high-latitude site in Fairbanks, Alaska (64°50'N, 147°50'W). We examined fat-deposition strategies during the final (spring) and initial (autumn) stages of long-distance migration, 1992–1998, to (1) improve understanding of geographic fat-deposition patterns by adding a high-latitude perspective; (2) determine whether there are age-related differences in fat-deposition strategies in autumn; and (3) test the “spring fatter” hypothesis of seasonal fat-deposition, which suggests that migrants should carry more fat in spring when they near their breeding areas than in autumn when they depart. Our analyses examined factors affecting daily fat scores during migration and compared between-season differences in fat stores among a total of 18,685 individuals of 16 migrant species. In autumn, adults had higher visible subcutaneous fat scores than immatures in 11 of 16 species. However, in all but two species, those differences were attributable to the effects of overnight low temperature, day length, and time of day, rather than age, probably because of later departures by adults. Fat scores were higher in autumn than in spring in 6 of 16 species, and body-condition indices were higher in autumn in 5 of 16 species. Only one species showed higher fat scores in spring, but that difference was not reflected in a seasonal comparison of body- condition indices. No species arrived with high fat loads in spring, and generally low fat levels in autumn suggest that high-latitude passerine migrants in North America are paying most of the energetic costs of long-distance migration with resources obtained en route to their wintering grounds. Among passerine migrants near these high-latitude breeding grounds, seasonal fat-deposition strategies appear to be responding to energetic needs at the level of daily maintenance, rather than to hypothesized insurance needs in spring or to the forthcoming needs of a long- distance migration in autumn.
Male Reproductive Success is Correlated With Blood Parasite Levels and Body Condition in the Promiscuous Aquatic Warbler (Acrocephalus Paludicola)
Authors: Dyrcz Andrzej , Wink Michael , Kruszewicz Andrzej , Leisler Bernd 
Published: September 2019

AbstractThe Aquatic Warbler (Acrocephalus paludicola) has a unique mating system. Males are free of any parental duties and can fertilize many females during a single breeding season. Females also usually copulate with more than one male, and nestlings in a single nest may be sired by as many as five males. Paternal success of 33 Aquatic Warbler males in a Polish population was determined by microsatellite polymerase-chain-reaction analysis. Males infected by blood parasites (trypanosomes) sired fewer offspring, weighed less, and probably arrived later to breeding grounds than uninfected males. Number of nestlings sired by a male correlated positively with its fat deposits and wing length. These findings indicate that male body condition directly influences paternal success. Number of sired nestlings per individual male ranged from one to eight. Reproductive success among males was uneven, with six males (18%) fathering 44% of nestlings in the study area. Males with high reproductive success arrived at the breeding grounds earlier in spring than males with low reproductive success.
Song Structure and Microgeographic Song Variation in Wedge-Tailed Sabrewings (Campylopterus Curvipennis) in Veracruz, Mexico
Authors: González Clementina , Ornelas Juan Francisco 
Published: September 2019

AbstractWe studied the songs of Wedge-tailed Sabrewings (Campylopterus curvipennis) in six localities from central Veracruz, Mexico, to document structure and variation within and between singing groups in the same geographic region. Wedgetailed Sabrewing songs were acoustically, structurally, and behaviorally complex, rivaling those of other taxa with complex signals. Songs of individual birds were composed of >45 well-differentiated and structurally complex syllables. We found 239 different syllable types across eight recorded singing groups of Wedge-tailed Sabrewings (∼20 syllable types per singing group), with the greatest versatility recorded in hummingbirds to date. The acoustic variation (15 variables) was summarized in three principal components (58% of acoustic variation), in which intragroup variability accounted for most of the observed variation. We found significant differences between and within groups in terms of syllable sharing (Jaccard’s similarity coefficient). Individuals generally shared >50% of syllable types within groups, whereas syllable sharing was <10% between individuals from different groups. The same microgeographic pattern was supported in a UPGMA (unweighted pair-group method with arithmetic mean) analysis where individual songs from each singing group clustered separately. However, songs recorded at the same location differed between seasons, which suggests that this species does not exhibit geographically distinct dialects that are consistent across time. The interplay among this species’ social system, distribution of its floral resources, and microgeographic and temporal variation of its song requires further research.
Phylogenetic Relationships of Antpitta Genera (Passeriformes: Formicariidae)
Authors: Rice Nathan H. 
Published: September 2019

Abstract
Phylogenetic relationships among the antpitta genera were studied using DNA sequence data from the mitochondrial genome. The clade representing the traditional “antpitta” genera (Grallaria, Grallaricula, Hylopezus, Myrmothera, and Pittasoma) was found to be paraphyletic, owing to the sister relationship of Pittasoma and Conopophaga. In a previously unreported relationship, Pittasoma was strongly supported as the sister genus to Conopophaga (Conopophagidae). The remaining antpitta genera form a fully resolved and well-supported monophyletic lineage with two major subclades. The first clade consists of the genus Grallaria and supports the subgenera identified by Lowery and O'Neill (1969). The second antpitta clade has Hylopezus as the sister genus to Myrmothera, with Grallaricula as their sister genus. The results here allow for a new interpretation of the morphological characters used in previous studies.
Additional Data on Mitochondrial DNA of North American Large Gull Taxa
Authors: Gay Laurène , Bell Douglas A. , Crochet Pierre-André 
Published: September 2019

Abstract
After publication of the Larus phylogeny in Crochet et al. (2002), the taxonomic status of the “Larus thayeri“ and the “L. occidentalis“ specimens that were used in that study came into question. For each of those species, we sequenced the same mitochondrial DNA regions in new specimens of known identity. In addition, specimens of L. glaucescens were included. Results from using those specimens confirm that L. occidentalis was the first to diverge from the large white-headed gulls. Larus glaucescens, on the contrary, is part of the Arctic species clade, which also includes L. hyperboreus, L. glaucoides, L. thayeri, and L. schistisagus. The three new L. thayeri specimens differ substantially in mitochondrial DNA from the previously used sample of L. thayeri and share the same haplotype with L. glaucescens. The significance of this finding is unclear, because relationships within the “Arctic species“ clade are still unresolved; that is attributable to the unusually high incidence of lineage sharing and extremely low divergence of haplotypes in the group.
Ultraviolet Degradation in Carotenoid Patches: Live Versus Museum Specimens of Wood Warblers (Parulidae)
Authors: McNett Gabriel D. , Marchetti Karen 
Published: September 2019

AbstractAccurate assessment of color is essential in testing the adaptive significance of color variation in avian plumage. Over the past decade, use of objective methods for assessing color has increased, with particular emphasis on ultraviolet (UV) wavelengths. Researchers have used various source materials, most notably museum specimens, to extend or represent color measurements of individuals in natural populations. Here, we address whether the colors seen in museum specimens accurately represent the colors seen in natural populations. We focus on UV wavelengths and carotenoid-derived colors across 10 species of wood-warblers (Parulidae). Our results indicate an uneven decrease in brightness across the color spectrum, with greater relative decrease in shorter wavelengths in museum specimens. That decrease leads to differences in both hue and chroma between living and museum specimens. The difference from live specimens appears to increase with the museum specimen's age. Our results suggest that caution is needed when using data from museum specimens to test hypotheses on plumage coloration, particularly those involving communication.Degradación Ultravioleta en Parches de Carotenoides: Especímenes Vivos versus Especímenes de Museo de Especies de la Familia Parulidae
Hippocampal Volume Does not Correlate With Food-Hoarding Rates in The Black-Capped Chickadee (Poecile Atricapillus) and Willow Tit (Parus Montanus)
Authors: Brodin Anders 
Published: September 2019

AbstractFood-hoarding birds use memory to relocate caches, and species that store thousands of scattered food items must have an extraordinary memory capacity to be able to relocate them. Because the hippocampus is important in the functioning of spatial memory, it is logical to assume that the amount of food stored should correlate with hippocampal volume. Previously, food-hoarding capacity has been used as the predictor variable for hippocampal volume. Using the opposite approach, I tested whether hippocampal volume can be used to predict the amount of food stored. The atricapilla complex, a superspecies in the Paridae, has a wide Holarctic distribution, with the Black-capped Chickadee (Poecile atricapillus) in America and the Willow Tit (Parus montanus) in Eurasia. Although they live in similar ecological conditions, the Willow Tit possesses a hippocampus almost twice the size of the Black-capped Chickadee's. I sampled hoarding intensities in Black-capped Chickadees in British Columbia with the same methods I used previously in Willow Tits in Sweden. Contrary to expectation, Black-capped Chickadees stored at the same high rates as Willow Tits, which suggests that both species are large-scale hoarders. I discuss possible explanations for why the difference in hippocampal volume did not translate into differences in food-hoarding rates.Le Volume de l'Hippocampe n'est pas Corrélé avec le Taux de Stockage de Nourriture Chez Poecile atricapillus et Parus montanus