Publications

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malarial parasites as geographical markers in migratory birds?we tested the hypothesis that malarial parasites (plasmodium and haemoproteus) of black-throated blue warblers (dendroica caerulescens) provide sufficient geographical signal to track population movements between the warbler's breeding and wintering habitats in north america. our results from 1083 warblers sampled across the species' breeding range indicate that parasite lineages are geographically widespread and do not provide site-specific information. the wide distribution of malarial parasit ...200617148365
organophosphate pesticide method development and presence of chlorpyrifos in the feet of nearctic-neotropical migratory songbirds from canada that over-winter in central america agricultural areas.recent modeling analysis suggests that numerous birds may be at risk of acute poisoning in insecticide-treated fields. although the majority of avian field studies on pesticides have focused on treated seed, granule, insect or vegetation (oral exposure) ingestion, dermal exposure is an important exposure route when birds come into contact with deposited pesticides on foliage and other surfaces. some nearctic-neotropical migratory songbirds are likely exposed to pesticides on their non-breeding h ...201626421621
resolving misaligned spatial data with integrated species distribution models.advances in species distribution modeling continue to be driven by a need to predict species responses to environmental change coupled with increasing data availability. recent work has focused on development of methods that integrate multiple streams of data to model species distributions. combining sources of information increases spatial coverage and can improve accuracy in estimates of species distributions. however, when fusing multiple streams of data, the temporal and spatial resolutions ...201930933314
sperm morphology and male age in black-throated blue warblers, an ecological model system.extra-pair paternity may drive selection on spermatozoa and ejaculate characteristics through sperm competition and cryptic female choice. here, we examine sperm morphology in the black-throated blue warbler (setophaga caerulescens), an ecological model species where extra-pair paternity is frequent and is linked with male age. we test whether sperm morphology relates to several aspects of male phenotype known or suspected to affect extra-pair paternity success. sperm morphology did not correlat ...202032664407
cross-scale effects of spruce budworm outbreaks on boreal warblers in eastern canada.insect outbreaks are major natural disturbance events that affect communities of forest birds, either directly by affecting the food supply or indirectly by changing the vegetation composition of forest canopies. an examination of correlations between measures of bird and insect abundance across different spatial scales and over varying time lag effects may provide insight into underlying mechanisms. we developed a hierarchical bayesian model to assess correlations between counts of eight warble ...201830151153
stable hydrogen isotope variability within and among plumage tracts (δ2hf) of a migratory wood warbler.hydrogen isotope analysis of feather keratin (δ2hf) has become an essential tool for tracking movements between breeding and wintering populations of migratory birds. in particular, δ2hf has been used to create δ2hf isoscapes that can be used to assign the geographic origins of molt. the majority of past studies have sampled a portion of a single feather as an isotopic proxy for the entire plumage although surprisingly little is known about variation of stable isotopes within and between feather ...201829614120
characterizing selection in black-throated blue warblers using a sexual network approach.our understanding of trait evolution is built upon studies that examine the correlation between traits and fitness, most of which implicitly assume all individuals experience similar selective environments. however, accounting for differences in selective pressures, such as variation in the social environment, can advance our understanding of how selection shapes individual traits and subsequent fitness. in this study, we test whether variation in the social environment affects selection on indi ...201728986958
correlates of bird collisions with buildings across three north american countries.collisions with buildings cause up to 1 billion bird fatalities annually in the united states and canada. however, efforts to reduce collisions would benefit from studies conducted at large spatial scales across multiple study sites with standardized methods and consideration of species- and life-history-related variation and correlates of collisions. we addressed these research needs through coordinated collection of data on bird collisions with buildings at sites in the united states (35), can ...202032537779
stable isotope signature of philopatry and dispersal in a migratory songbird.stable isotope analysis is widely promoted as a practical method for tracing the geographic origins of migratory birds. however, the extent to which geospatial patterns of isotope ratios in avian tissues are influenced by age-specific, altitudinal, and temporal factors remains largely unexplored. we measured carbon ((13)c/(12)c) and nitrogen ((15)n/(14)n) isotope ratios in feathers of black-throated blue warblers (dendroica caerulescens) breeding along a relatively steep altitudinal gradient in ...200212034868
multiple density-dependence mechanisms regulate a migratory bird population during the breeding season.the mechanisms regulating bird populations are poorly understood and controversial. we provide evidence that a migratory songbird, the black-throated blue warbler (dendroica caerulescens), is regulated by multiple density-dependence mechanisms in its breeding quarters. evidence of regulation includes: stability in population density during 1969-2002, strong density dependence in time-series analyses of this period, an inverse relationship between warbler density and annual fecundity, and a posit ...200314561272
stable isotope ratios indicate that body condition in migrating passerines is influenced by winter habitat.although predicted some time ago, there has been little success in demonstrating that the overall fitness of migratory birds depends on the combined influences of their experiences over all seasons. we used stable carbon isotope signatures (delta13c) in the claws of migrating black-throated blue warblers dendroica caerulescens to infer their wintering habitats and investigated whether winter habitat selection can be linked to condition during migration. resident bird species with low delta13c co ...200415252988
genetic divergence and migration patterns in a north american passerine bird: implications for evolution and conservation.like many other migratory birds, the black-throated blue warbler (dendroica caerulescens) shows pronounced differences in migratory behaviour and other traits between populations: birds in the southern part of the breeding range have darker plumage and migrate to the eastern caribbean during the winter, whereas those in the north have lighter plumage and migrate to the western caribbean. we examined the phylogeography of this species, using samples collected from northern and southern population ...200616780431
social information trumps vegetation structure in breeding-site selection by a migrant songbird.to maximize fitness, organisms must assess and select suitable habitat. early research studying birds suggested that organisms consider primarily vegetation structural cues in their habitat choices. we show that experimental exposure to singing in the post-breeding period provides a social cue that is used for habitat selection the following year by a migrant songbird, the black-throated blue warbler (dendroica caerulescens). our experimental social cues coerced individuals to adopt territories ...200818559326
bet-hedging and the orientation of juvenile passerines in fall migration.1. bet-hedging of innate migratory orientation of juvenile passerines may be a fitness-enhancing strategy for fall migration. experimental studies support the view that juvenile passerines on their first migration to unknown winter grounds orient on a predetermined vector programme and make little or no adjustment for wind displacement. this trait, coupled with the unpredictable profile of wind speed and direction that the juvenile will encounter during migration, suggests that the fitness of a ...200919572960
mesoscale patterns of altitudinal tenancy in migratory wood warblers inferred from stable carbon isotopes.we analyzed carbon isotope ratios (delta13c) of liver and pectoral muscle of black-throated blue warblers (dendroica caerulescens) to provide a mesoscale perspective on altitudinal tenancy in the appalachian mountains, north carolina, u.s.a. movements of males are poorly understood, particularly the degree to which yearlings (first breeding season) and older males (second or later breeding season) wander altitudinally during the breeding season. liver and muscle delta13c values of warblers exhib ...200919688933
lidar remote sensing variables predict breeding habitat of a neotropical migrant bird.a topic of recurring interest in ecological research is the degree to which vegetation structure influences the distribution and abundance of species. here we test the applicability of remote sensing, particularly novel use of waveform lidar measurements, for quantifying the habitat heterogeneity of a contiguous northern hardwoods forest in the northeastern united states. we apply these results to predict the breeding habitat quality, an indicator of reproductive output of a well-studied neotrop ...201020583698
warm springs, early lay dates, and double brooding in a north american migratory songbird, the black-throated blue warbler.numerous studies have correlated the advancement of lay date in birds with warming climate trends, yet the fitness effects associated with this phenological response have been examined in only a small number of species. most of these species--primarily insectivorous cavity nesters in europe--exhibit fitness declines associated with increasing asynchrony with prey. here, we use 25 years of demographic data, collected from 1986 to 2010, to examine the effects of spring temperature on breeding init ...201323565154
escalation of aggressive vocal signals: a sequential playback study.rival conspecifics often produce stereotyped sequences of signals as agonistic interactions escalate. successive signals in sequence are thought to convey increasingly pronounced levels of aggressive motivation. here, we propose and test a model of aggressive escalation in black-throated blue warblers, presenting subjects with two sequential and increasingly elevated levels of threat. from a speaker outside the territorial boundary, we initiated an interaction (low-threat level), and from a seco ...201323926156
inferences about population dynamics from count data using multistate models: a comparison to capture-recapture approaches.wildlife populations consist of individuals that contribute disproportionately to growth and viability. understanding a population's spatial and temporal dynamics requires estimates of abundance and demographic rates that account for this heterogeneity. estimating these quantities can be difficult, requiring years of intensive data collection. often, this is accomplished through the capture and recapture of individual animals, which is generally only feasible at a limited number of locations. in ...201424634726
a comprehensive analysis of small-passerine fatalities from collision with turbines at wind energy facilities.small passerines, sometimes referred to as perching birds or songbirds, are the most abundant bird group in the united states (us) and canada, and the most common among bird fatalities caused by collision with turbines at wind energy facilities. we used data compiled from 116 studies conducted in the us and canada to estimate the annual rate of small-bird fatalities. it was necessary for us to calculate estimates of small-bird fatality rates from reported all-bird rates for 30% of studies. the r ...201425222738
experimental food supplementation reveals habitat-dependent male reproductive investment in a migratory bird.environmental factors can shape reproductive investment strategies and influence the variance in male mating success. environmental effects on extrapair paternity have traditionally been ascribed to aspects of the social environment, such as breeding density and synchrony. however, social factors are often confounded with habitat quality and are challenging to disentangle. we used both natural variation in habitat quality and a food supplementation experiment to separate the effects of food avai ...201525673677
the interacting effects of food, spring temperature, and global climate cycles on population dynamics of a migratory songbird.although long-distance migratory songbirds are widely believed to be at risk from warming temperature trends, species capable of attempting more than one brood in a breeding season could benefit from extended breeding seasons in warmer springs. to evaluate local and global factors affecting population dynamics of the black-throated blue warbler (setophaga caerulescens), a double-brooded long-distance migrant, we used pradel models to analyze 25 years of mark-recapture data collected in new hamps ...201626242236
a comparative assessment of snp and microsatellite markers for assigning parentage in a socially monogamous bird.single-nucleotide polymorphisms (snps) are preferred over microsatellite markers in many evolutionary studies, but have only recently been applied to studies of parentage. evaluations of snps and microsatellites for assigning parentage have mostly focused on special cases that require a relatively large number of heterozygous loci, such as species with low genetic diversity or with complex social structures. we developed 120 snp markers from a transcriptome assembled using rna-sequencing of a so ...201727488248
ecological and social factors constrain spatial and temporal opportunities for mating in a migratory songbird.many studies of sexual selection assume that individuals have equal mating opportunities and that differences in mating success result from variation in sexual traits. however, the inability of sexual traits to explain variation in male mating success suggests that other factors moderate the strength of sexual selection. extrapair paternity is common in vertebrates and can contribute to variation in mating success and thus serves as a model for understanding the operation of sexual selection. we ...201728221825
the effect of predation on begging-call evolution in nestling wood warblers.i combined a comparative study of begging in ground- and tree-nesting wood warblers (parulidae) with experimental measures of the predation costs of warbler begging calls. throughout their development, ground-nesting warbler nestlings had significantly higher-frequency begging calls than did tree-nesting warblers. there was also a trend for ground-nesting birds to have less rapidly modulated calls. there were no consistent associations between nesting site and the amplitude of the calls. using m ...199910202097
factors affecting aural detections of songbirds.many factors affect the number of birds detected on point count surveys of breeding songbirds. the magnitude and importance of these factors are not well understood. we used a bird song simulation system to quantify the effects of detection distance, singing rate, species differences, and observer differences on detection probabilities of birds detected by ear. we simulated 40 point counts consisting of 10 birds per count for five primary species (black-and-white warbler mniotilta varia, black-t ...200717494409
the use of isotope tracers for identifying populations of migratory birds.to determine whether stable isotopes can be used for identifying the geographic origins of migratory bird populations, we examined the isotopic composition of hydrogen (deuterium, δd), carbon (δ(13)c), and strontium (δ(87)sr) in tissues of a migratory passerine, the black-throated blue warbler (dendroica caerulescens), throughout its breeding range in eastern north america. δd and δ(13)c values in feathers, which are grown in the breeding area, varied systematically along a latitudinal gradient, ...199628307603
impacts of a global climate cycle on population dynamics of a migratory songbird.progress toward understanding factors that limit abundances of migratory birds, including climate change, has been difficult because these species move between diverse locations, often on different continents. for black-throated blue warblers (dendroica caerulescens), demographic rates in both tropical winter quarters and north temperate breeding grounds varied with fluctuations in the el niño southern oscillation. adult survival and fecundity were lower in el niño years and higher in la niña ye ...200010856216
determining the sources of calcium for migratory songbirds using stable strontium isotopes.we investigated natural variations in the stable isotopic composition of strontium (a surrogate for calcium) in the bones of a single species of breeding migratory songbird, as well as in their eggshells, egg contents, and food sources. we use this information to determine the sources of calcium to these migratory songbirds and their offspring. samples were collected from two locations in the northeastern usa (hubbard brook, nh, and downer forest, vt.) that differed in soil geochemistry. the mea ...200128547242
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