bluuebunny/crossref_metadata_2025_split huggingface dataset:
Grounded Ground Birds and Surfing Canopy Birds: Variation of Foraging Stratum Breadth Observed in Neotropical Forest Birds and Tested With Simulation Models Using Boundary Constraints
Authors: Walther Bruno A. 
Published: September 2019

AbstractVertical stratification of bird species has been intensively studied in temperate as well as tropical forest bird communities. One question that has received less attention is the variation of foraging stratum breadth. Hypotheses trying to explain that variation are based on differences in perception, evasion, adaptation, competition, and environmental and geometric boundary constraints. Although some predict that foraging strata near the ground should be narrower than those near the canopy, others predict that strata in the midstory should be broadest. These hypotheses were tested using observational data of 92 rainforest bird species. Observations were made from or near a 40 m high canopy crane situated close to the Surumoni River (3°10′N, 65°40′W) near Esmeralda, Estado Amazonas, southern Venezuela (Surumoni-Crane-Project). I found a highly significant parabolic relationship between mean foraging height and its standard deviation showing that midstory bird species foraged in a broader stratum than either understory or canopy species. Using a conservative comparative method, I also showed that the relationship was not the result of the phylogenetic relatedness of the species involved. Analysis of previously published data supports the relationship for two other tropical avifaunas. Because the ground and the outer canopy represent geometric boundaries to the movement of most forest birds, two simulation models were used to test whether midstory species may simply have a broader stratum because they are less constrained in their movements than species near the boundaries. The “random model” allowed individuals to move randomly between the two boundaries. It illustrated that boundary constraints alone cannot explain the observed parabolic relationship. In the “preference model,” individuals tended to move back to their preferred height within the forest column. That model simulated the observed parabolic relationship once a sufficient number of time steps had been reached, suggesting that a simple combination of geometric boundaries and preference for a specific foraging height may generate narrower strata near the boundaries. The other hypotheses only explain the parabolic relationship if other factors (e.g. vegetation density) are vertically distributed in such a way as to generate the observed parabolic pattern. Finally, I briefly discuss the advantages and disadvantages of using raw data in across-species analyses versus corrected data in phylogenetically-controlled analyses.
What is a Wood-Warbler? Molecular Characterization of a Monophyletic Parulidae
Authors: Lovette I. J. , Bermingham E. 
Published: September 2019

AbstractThe wood-warblers (family Parulidae) fall within a radiation of passerine birds commonly known as the New World nine-primaried oscines. Defining familial relationships within that radiation has previously been challenging because of its extremely high diversity, a paucity of phylogenetically informative morphological characters, and an apparent high rate of cladogenesis early in the radiation's history. Here, analyses of mitochondrial and nuclear DNA sequences demonstrate that the 25 extant genera traditionally placed in the Parulidae do not form a monophyletic group. Instead, all reconstructions identify a well-resolved clade of 19 genera (Vermivora, Parula, Dendroica, Catharopeza, Mniotilta, Setophaga, Protonotaria, Helmitheros, Limnothlypis, Seiurus, Oporornis, Geothlypis, Wilsonia, Cardellina, Ergaticus, Myioborus, Euthlypis, Basileuterus, and Phaeothlypis) that are all morphologically typical wood-warblers traditionally placed in the Parulidae. Six genera traditionally assigned to the Parulidae—Microligea, Teretistris, Zeledonia, Icteria, Granatellus, and Xenoligea—fall outside this highly supported clade in all mtDNA-based and nuclear DNA-based reconstructions, and each is probably more closely allied to taxa traditionally placed in other nine-primaried oscine families. The long, well-supported, and independently confirmed internode at the base of this wood-warbler clade provides the opportunity to define a monophyletic Parulidae using several complementary molecular phylogenetic criteria. Support for those relationships comes from reconstructions based on a range of nucleotide-intensive (from 894 to 3,638 nucleotides per taxon) and taxon-intensive (45 to 128 species) analyses of mtDNA sequences, as well as independent reconstructions based on nucleotide substitutions in the nuclear-encoded c-mos gene. Furthermore, the 19 typical wood-warbler genera share a synapomorphic one-codon c-mos deletion not found in other passerines. At a slightly deeper phylogenetic level, our mtDNA-based reconstructions are consistent with previous morphologic and genetic studies in suggesting that many nine-primaried oscine taxa have unanticipated affinities, that many lineages arose during an early and explosive period of cladogenesis, and that the generation of a robust nine-primaried oscine phylogeny will require robust taxonomic sampling and extensive phylogenetic information.
Phylogeny of the Tyrant Flycatchers (Tyrannidae) Based on Morphology and Behavior
Authors: Birdsley Jeffrey S. 
Published: September 2019

AbstractPreviously published morphological and behavioral data for the tyrant flycatchers (Tyrannidae) were reanalyzed using cladistic techniques. Several additional characters, including two putative synapomorphies of the Tyrannidae were incorporated. Nearly all of the ∼100 traditional tyrannid genera were included. Results of the analysis of this set of 68 characters support three previously proposed tyrannid assemblages: the kingbird assemblage and slightly restricted Empidonax and Myiarchus assemblages. Characters of the nasal septum that past workers have considered conservative and phylogenetically informative are supported as synapomorphies of the kingbird and restricted Empidonax assemblages. Several small monophyletic groups of genera are supported. The monophyly of neither the Elaenia assemblage nor the flatbill and tody-tyrant assemblage is supported in any most-parsimonious tree, but such trees are not significantly better than trees supporting their monophyly. A Tyrannidae exclusive of the Cotingidae and Pipridae is monophyletic in some most-parsimonious trees, but not in others in which flatbills and tody-tyrants are basal to a clade containing Cotingidae, Pipridae, and the remaining tyrannid genera. There is some evidence that characters describing plumage color pattern are more homoplasious than the other character suites I examined.
Age-Related Trends in Different Aspects of the Breeding Performance of Individual Female Eurasian Sparrowhawks (Accipiter Nisus)
Authors: Newton Ian , Rothery Peter 
Published: September 2019

AbstractAge-related trends in breeding performance of female Eurasian Sparrowhawks (Accipiter nisus) were examined in south Scotland. Over a 22 year period, most individuals were banded and of known age. Previous analyses had shown that average number of young raised per breeding attempt (or year) increased progressively in successive age-groups to midlife (around five years) and declined thereafter. Here we analyze different components of breeding performance (such as clutch-size, hatching and fledging success) to find which components contribute most importantly to the overall age-related trend in productivity. Most aspects of breeding showed a similar upward–downward trend through the life span, but the downward trend in productivity in later life could be attributed mainly to poorer nestling survival. In general, in each aspect of breeding, the mean trend of the population as a whole was followed by individuals studied at different ages. Such individual trends were sufficient to account for the overall mean trend, and there was no need to postulate that high-performance or low-performance birds entered and left the breeding population at different ages. Only one aspect of breeding showed no trend with age, namely proportion of birds that laid having built a nest, but that type of failure affected only a small proportion of individuals.
Estimating Species Richness of Tropical Bird Communities From Rapid Assessment Data
Authors: Herzog Sebastian K. , Kessler Michael , Cahill Thomas M. 
Published: September 2019

AbstractRapid assessment surveys of tropical bird communities are increasingly used to estimate species richness and to determine conservation priorities, but results of different studies are often not comparable due to the lack of standardization. On the basis of computer simulations and six years of field testing, we evaluated the recently proposed “20-species-list” survey method and statistical estimators for assessing species richness of tropical bird communities. This method generates a species-accumulation curve by subdividing consecutive observations of birds into lists of 20 species, thus relating cumulative species richness to the number of observations rather than time or space and thereby accounting for moderate differences in observer qualification and field conditions. Species accumulation curves from computer-simulated communities and two empirical data sets from Bolivia were analyzed with nine species richness estimators to evaluate estimator accuracy with respect to variations in species-list size, sample size, species-pool size, and community structure. For empirical and most simulated data sets, the MMMEAN estimator performed best, but it was more sensitive to differences in community structure than most other estimators. The CHAO 2 estimator, which was recommended by previous studies, performed reasonably well but was considerably more sensitive to sample size than MMMEAN. The bootstrap and first- and second-order jackknife estimators performed poorly. We recommend using MMMEAN or, when standard deviations of richness estimates are indispensable, CHAO 2 with 10-species lists for estimating species richness of tropical bird communities and propose a set of standard survey rules. Careful examination of estimator accumulation curves is required, however, and a technique based on the ratio between estimator and species accumulation curve is suggested to control for the confounding effects of sampling effort. Overall, the species-list method combined with statistical richness estimation is doubtlessly much more standardized and valuable than simple comparisons of one-dimensional locality lists and represents a promising tool for conservation assessment and the study of avian diversity patterns in the tropics.
Effects of Dispersal on Survival Probability of Adult Yellow Warblers (Dendroica Petechia)
Authors: Cilimburg Amy B. , Lindberg Mark S. , Tewksbury Joshua J. , Hejl Sallie J. 
Published: September 2019

AbstractAnnual survival probability estimates for songbirds are generally biased low because dispersal is not differentiated from mortality. Presently, knowledge of between-year breeding dispersal is lacking for most songbirds. To assess adult survival probabilities and dispersal, we color-banded and resighted 436 Yellow Warblers (Dendroica petechia) over five breeding seasons at 11 study sites in the Bitterroot Valley, Montana. During the last two of those seasons, we searched extensively for marked warblers between and surrounding those sites. We compared survival probabilities estimated with and without this added dispersal information and assessed the effectiveness of adjusting survival probabilities with transient-type models. Survival probabilities were calculated using open population models, and model selection was based on Akaike's Information Criterion (AIC) within program MARK. The best model indicated that survival probabilities differed between males and females and varied among years. We found that dispersal off the study site was common (in 1999, 30% of resighted birds were found off their original study site), and survival probabilities increased by 6.5–22.9% (0.02 ± 0.07−0.106 ± 0.06) with the inclusion of dispersed birds. We suggest that emigration can have substantial effect on survival probabilities and advise against the use of return rates from small study areas or spatial or temporal comparisons of return rates because of spatial and temporal variation in extent of emigration. In addition, our results suggest that additional assessments of the reliability of transient-type models under some sampling schemes may be warranted.
Cooperatively Breeding Groups of Carrion Crow(Corvus Corone Corone) in Northern Spain
Authors: Baglione Vittorio , Marcos José M. , Canestrari Daniela 
Published: September 2019

AbstractThe Carrion Crow (Corvus corone) is almost invariably reported as a species breeding as unassisted pairs, but a population of Carrion Crows (Corvus c. corone) from northern Spain that we have been studying since 1995 regularly exhibits cooperative breeding. The Spanish population thus demonstrates that cooperative breeding can vary greatly across populations. Most of the breeding territories (73.3%) in Spain were held by cohesive groups, which consisted of up to nine birds (mode = 3 birds). The proportion of fledglings that delayed dispersal for one year varied between 12.2 and 47.5% for different cohorts. The corresponding values for juveniles postponing dispersal for two years were 4.9 and 19.2%. Philopatry was skewed toward males. Some social groups contained immigrants. Therefore, delayed juvenile dispersal was not the only route towards sociality. Up to three helpers provided food to the nestling and at least one helper was found in all the groups surveyed. However, some group members refrained from visiting nests and thus the contribution to nestling care was highly variable among individuals.
Scare Tactics in a Neotropical Warbler: White Tail Feathers Enhance Flush–Pursuit Foraging Performance in the Slate-Throated Redstart (Myioborus Miniatus)
Authors: Mumme Ronald L. 
Published: September 2019

AbstractFlush–pursuit foragers use exaggerated and animated foraging movements to flush potential prey that are then pursued and captured in flight. The Myioborus redstarts comprise 12 species of flush–pursuit warblers found in montane forests of the American tropics and subtropics. All members of the genus have contrasting black-and-white tail feathers that are exposed by spreading the tail during animated foraging displays. Plumage pattern and tail-spreading behavior were examined to see how they affected flush–pursuit foraging performance of the Slate-throated Redstart (Myioborus miniatus) in Monteverde, Costa Rica. Although flycatching was the most common foraging tactic used by Slate-throated Redstarts, flush–pursuit foraging increased in both frequency and intensity when birds were feeding nestlings. Flush–pursuit prey attacks occurred more frequently following hops in the spread-tail foraging posture than hops in more typical warbler-like posture, suggesting that tail-spreading behavior assists in startling and flushing potential prey. The hypothesis that the white tail feathers enhance flush–pursuit foraging was tested by means of a plumage-dyeing experiment. After locating nests containing young 5–7 days old, I captured the male and female at the nest and assigned one member of each pair to the experimental treatment group; its mate served as a control. For experimental birds, a permanent marker was used to blacken the white tips of the three outer retrices. For sham-darkened controls, the naturally black tips of the three inner retrices were also “blackened”. Experimental birds with darkened tail feathers were significantly less successful in flush–pursuit foraging, showed a significantly lower overall rate of prey attack, and fed their nestlings at a significantly lower rate than did their sham-darkened mates. For experimental birds, only 7.6% of hops in the spread-tail posture were followed by an attack on a prey item, compared to 20.9% of hops for controls. These experimental results, similar to those obtained recently by Jabłoński (1999) for the congeneric Painted Redstart (Myioborus pictus), indicate that white tail feathers are critically important in startling potential prey and raise questions about interspecific and intraspecific geographic variation in plumage pattern in the genus.
Functional Morphology of Raptor Hindlimbs: Implications for Resource Partitioning
Authors: Ward Andrea B. , Weigl Peter D. , Conroy Rachael M. 
Published: September 2019

Abstract
Prey capture in owls and hawks is largely dependent on the biomechanics of the hindlimbs, and both limb size and grip forces potentially determine the size of prey that can be captured and the extent of possible resource partitioning among sympatric species. Morphological study of six species of sympatric raptors—the owls Otus asio, Strix varia, and Bubo virginianus; and the hawks commonly considered their diurnal “ecological equivalents,” Falco sparverius, Buteo lineatus, and Buteo jamaicensis—revealed that, in both groups, talon closure is effected by two discrete mechanisms that function together in a potentially additive or alternative fashion. Grip force measurements obtained from live owls and hawks using “hydraulic” perches showed that grip force increases exponentially with body size and that owls produce greater forces than hawks. That finding is consistent with the distinctive osteology and myology of their hindlimbs and with their hunting behavior. These data provide some understanding of the different demands of diurnal and nocturnal hunting as well as the mechanism of coexistence for those six species in eastern woodlands.
A Multifaceted Approach to the Characterization of an Intergeneric Hybrid Manakin (Pipridae) from Brazil
Authors: Marini Miguel Â , Hackett Shannon J. 
Published: September 2019

Abstract
A new intergeneric hybrid manakin is characterized using morphological characters and mitochondrial and nuclear DNA sequences. Many morphological traits suggest the bird is intermediate between Ilicura militaris and Chiroxiphia caudata. Sequences of the maternally inherited mitochondrial ND2 gene demonstrate the female parent to be Chiroxiphia caudata, and the nuclear beta-fibrinogen intron 5 sequences can not eliminate Chiroxiphia and Ilicura as parents. Therefore, DNA sequence data lead to the conclusion that Ilicura is the male parent of this unusual bird. This study is important because it highlights the significance of using multiple character systems in diagnosing unusual bird specimens.
Daily Energy Expenditures of Free-Ranging Common Loon (Gavia immer) Chicks
Authors: Fournier François , Karasov William H. , Meyer Michael W. , Kenow Kevin P. 
Published: September 2019

AbstractWe measured the daily energy expenditure of free-living Common Loon (Gavia immer) chicks using doubly labeled water (DLW). Average body mass of chicks during the DLW measures were 425, 1,052, and 1,963 g for 10 day-old (n = 5), 21 day-old (n = 6), and 35 day-old (n = 6) chicks, respectively, and their mean daily energy expenditures (DEE) were 686 kJ day−1, 768 kJ day−1, and 1,935 kJ day−1, respectively. Variation in DEE was not due solely to variation in body mass, but age was also a significant factor independent of body mass. Energy deposited in new tissue was calculated from age-dependent tissue energy contents and measured gains in body mass, which were 51, 54, and 33 g day−1 from the youngest to oldest chicks. Metabolizable energy (the sum of DEE and tissue energy) was used to estimate feeding rates of loon chicks and their exposure to mercury in the fish they consume. We calculated that loon chicks in Wisconsin consumed between 162 and 383 g wet mass of fish per day (depending on age), corresponding to intakes of mercury of 16–192 μg day−1.
Epizootiology and Effect of Avian Pox on Hawaiian Forest Birds
Authors: van Riper Charles , van Riper Sandra G. , Hansen Wallace R. 
Published: September 2019

Abstract
We determined prevalence and altitudinal distribution of forest birds infected with avian pox at 16 locations on Hawaii, from sea level to tree line in mesic and xeric habitats, during 1977–1980. Isolates from lesions were cultured in the laboratory for positive identification of Poxvirus avium. Infected birds from the wild were brought into the laboratory to assess differences in the course of infection in native versus introduced species. We also documented distributions and activity cycles of potential avian pox vectors.>Native forest birds were (1) more susceptible to avian pox infection than were introduced species, (2) most likely to be infected during the wet season, and (3) found to have a higher prevalence in mesic when compared to xeric forests. Avian pox occurred in forest birds at all elevations, but highest levels were in the mid-elevational ranges (∼1,200 m) where vectors and native birds had the greatest overlap. Temporal and elevational differences in prevalence were apparent throughout the annual cycle. Avian pox probably did not reach epizootic proportions on Hawaii until after introduction of the mosquito and domestic birds in the early 1800s, and since then has had a negative effect on the population dynamics of native forest birds. Today, this introduced disease is an important factor that should be considered in future conservation efforts that are directed at the recovery of native forest birds in Hawaii.
Ephemeral Food Resources and High Conspecific Densities as Factors Explaining Lack of Feeding Territories in Northern Flickers (Colaptes Auratus)
Authors: Elchuk Candace L. , Wiebe Karen L. 
Published: September 2019

Abstract
If Northern Flickers (Colaptes auratus) defend feeding territories was investigated by examining home-range overlap, social interactions at foraging sites, and the predictability and subsequent defendability of their main food source, ants. Flickers did not defend feeding territories, foraging with conspecifics in 29% of observations without visible aggressive behavior. Mean (± SD) percent cumulative home-range overlap between radiotagged individuals was 50 ± 32%; competitor density was positively related to overlap. Rain and temperature extremes reduced surface activity of potential ant prey. Simulated foraging over time decreased the number of active anthills in plots when compared to controls. Food predictability and competitive pressure may act together to make territories uneconomical for flickers to defend.
Apparent Survival Rates of Western Sandpiper (Calidris Mauri) Wintering in Northwest Baja California, Mexico
Authors: Fernández Guillermo , Cueva Horacio de la , Warnock Nils , Lank David B. 
Published: September 2019

AbstractTo estimate annual apparent local survival, we collected capture–resighting data on 256 individually marked male Western Sandpipers (Calidris mauri) wintering at Estero de Punta Banda, Mexico, between 1994–1997. A hierarchical modeling approach was used to address the effect of age class and year on survivorship rates. The best-fit model included a constant apparent survival probability (ϕ = 0.489; 95% CI = 0.410–0.569), but several models fit nearly as well, and averaging among the top five, to account for model uncertainty, suggested that adults had somewhat higher values than juveniles (ϕ = 0.490 ± 0.051 vs. 0.450 ± 0.067). Detection probability was substantially higher for adults than for juveniles (p = 0.741 vs. p = 0.537). Those apparent survival estimates are low compared with those from other studies of Western Sandpipers at breeding and other nonbreeding locations, and substantially lower than the true survivorship rates expected for small sandpipers in general. We interpret these results as indicating that this site is of below average quality for nonbreeding male Western Sandpipers.