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partial and complete dependency among data sets has minimal consequence on estimates from integrated population models.integrated population models (ipms) are widely used to combine disparate data sets in joint analysis to better understand population dynamics and provide guidance for conservation activities. an often-cited assumption of ipms is independence among component data sets within the combined likelihood. dependency among data sets should lead to underestimation of variance and bias because individuals contribute data to> 1 data set. in practice, studied individuals often occur in multiple data sets in ...202033176007
maternal glucocorticoid levels during incubation predict breeding success, but not reproductive investment, in a free-ranging bird.the hormone corticosterone (cort) has been hypothesized to be linked with fitness, but the directionality of the relationship is unclear. the 'cort-fitness hypothesis' proposes that high levels of cort arise from challenging environmental conditions, resulting in lower reproductive success (a negative relationship). in contrast, the cort-adaptation hypothesis suggests that, during energetically demanding periods, cort will mediate physiological or behavioral changes that result in increased repr ...202033077551
birds advancing lay dates with warming springs face greater risk of chick mortality.in response to a warming planet with earlier springs, migratory animals are adjusting the timing of essential life stages. although these adjustments may be essential for keeping pace with resource phenology, they may prove insufficient, as evidenced by population declines in many species. however, even when species can match the tempo of climate change, other consequences may emerge when exposed to novel conditions earlier in the year. here, using three long-term datasets on bird reproduction, ...202032989166
short-term exposure to unmanned aerial vehicles does not alter stress responses in breeding tree swallows.recent studies suggest that visual and acoustic anthropogenic disturbances can cause physiological stress in animals. human-induced stress may be particularly problematic for birds as new technologies, such as drones, increasingly invade their low-altitude air space. although professional and recreational drone usage is increasing rapidly, there is little information on how drones affect avian behavior and physiology. we examined the effects of drone activity on behavior and physiology in adult, ...202032864138
environmental unpredictability shapes glucocorticoid regulation across populations of tree swallows.the ability to respond appropriately to challenges is an important contributor to fitness. variation in the regulation of glucocorticoid hormones, which mediate the phenotypic response to challenges, can therefore influence the ability to persist in a given environment. we compared stress responsiveness in four populations of tree swallows (tachycineta bicolor) breeding under different environmental conditions to evaluate support for different selective pressures in driving the evolution of gluc ...202032792550
mercury exposure to swallows breeding in canada inferred from feathers grown on breeding and non-breeding grounds.aerial insectivorous birds such as swallows have been the steepest declining groups of birds in north america over the last 50 years but whether such declines are linked to contaminants has not been examined. we sampled feathers from five species of swallow at multiple locations to assess total mercury [thg] exposure for adults during the non-breeding season, and for juveniles on the breeding grounds. we assessed hg exposure to juvenile birds in crop- and grass-dominated landscapes to determine ...202032656653
legacy and contaminants of emerging concern in tree swallows along an agricultural to industrial gradient: maumee river, ohio.exposure to multiple classes of contaminants, both legacy and contaminants of emerging concern (cecs), were assessed in tree swallow (tachycineta bicolor) tissue and diet samples from 6 sites along the maumee river, ohio, usa, to understand both exposure and possible effects of exposure to those cecs for which there are little avian data. the 6 sites represented a gradient from intensive agriculture upstream to highly urbanized and industrial landscapes downstream; 1 or 2 remote wisconsin lakes ...202032495340
full lifetime perspectives on the costs and benefits of lay-date variation in tree swallows.animals must balance various costs and benefits when deciding when to breed. the costs and benefits of breeding at different times have received much attention, but most studies have been limited to investigating short-term season-to-season fitness effects. however, breeding early, versus late, in a season may influence lifetime fitness over many years, trading off in complex ways across the breeder's lifespan. in this study, we examined the complete life histories of 867 female tree swallows (t ...202032455498
heat dissipation capacity influences reproductive performance in an aerial insectivore.climatic warming is predicted to increase the frequency of extreme weather events, which may reduce an individual's capacity for sustained activity because of thermal limits. we tested whether the risk of overheating may limit parental provisioning of an aerial insectivorous bird in population decline. for many seasonally breeding birds, parents are thought to operate close to an energetic ceiling during the 2-3 week chick-rearing period. the factors determining the ceiling remain unknown, altho ...202032321750
population decline in tree swallows (tachycineta bicolor) linked to climate change and inclement weather on the breeding ground.population decline and the threat of extinction are realities currently facing many species. yet, in most cases, the detailed demographic data necessary to identify causes of population decline are unavailable. using 43 years (1975-2017) of data from a box-nesting population of tree swallows (tachycineta bicolor), we identified reduced survival of offspring as a probable demographic cause of population decline. poor fledging success was associated with increased predation and poor weather condit ...202032100152
impacts of environmental heterogeneity on natural selection in a wild bird population.natural selection has been studied for several decades, resulting in the computation of thousands of selection estimates. although the importance of environmental conditions on selection has often been suggested, published estimates rarely take into account the effects of environmental heterogeneity on selection patterns. here, we estimated linear and nonlinear viability selection gradients on morphological traits of 12-day old nestlings in a wild population of tree swallows (tachycineta bicolor ...202032052429
cloacal bacterial communities of tree swallows (tachycineta bicolor): similarity within a population, but not between pair-bonded social partners.host-associated microbial communities can influence the overall health of their animal hosts, and many factors, including behavior and physiology, can impact the formation of these complex communities. bacteria within these communities can be transmitted socially between individuals via indirect (e.g., shared environments) or direct (e.g., physical contact) pathways. limited research has been done to investigate how social interactions that occur in the context of mating shape host-associated mi ...202032045456
do songbirds in wetlands show higher mercury bioaccumulation relative to conspecifics in non-wetland habitats?environmental conditions in wetlands facilitate favorable biogeochemical conditions for the conversion of inorganic mercury into methylmercury. for this reason, wetlands are increasingly classified as mercury hotspots, places where biota exhibit elevated mercury concentrations. while it is clear that wetlands play an important role in methylmercury production, factors such as geographic variation in mercury deposition, wetland type, and trophic dynamics can cause variation in mercury dynamics an ...202031942663
expanding our view of bartonella and its hosts: bartonella in nest ectoparasites and their migratory avian hosts.bartonella is a genus of gram-negative facultative intracellular alphaproteobacteria of public health importance. although they are known to mainly infect mammalian hosts with some blood-feeding arthropods having been confirmed as vectors, there is some evidence of bartonella association with non-mammalian hosts including birds.202031924262
host tolerance and resistance to parasitic nest flies differs between two wild bird species.hosts have developed and evolved defense strategies to limit parasite damage. hosts can reduce the damage that parasites cause by decreasing parasite fitness (resistance) or without affecting parasite fitness (tolerance). because a parasite species can infect multiple host species, determining the effect of the parasite on these hosts and identifying host defense strategies can have important implications for multi-host-parasite dynamics.over 2 years, we experimentally manipulated parasitic flie ...201931832149
developmental temperature predicts the adult response to stressors in a free-living passerine.early-life conditions can have substantial effects on the ways animals respond to stressors as adults. in particular, thermal conditions during development affect juveniles' responses to stressors, and there is evidence that these effects may extend into adulthood. however, these effects remain poorly understood, especially in free-living organisms. we test the prediction that ambient temperatures during laying, embryonic development and nestling development affect the hormonal mediators of the ...202031792967
feather mites of the genus trouessartia canestrini (acariformes: trouessartiidae) from swallows (passeriformes: hirundinidae) in canada.seven species of the feather mite genus trouessartia canestrini, 1899 (astigmata: trouessartiidae) have been recorded on swallows and martins (passeriformes: hirundinidae) in manitoba (canada). of them, five are described as new species: trouessartia ampulicaudata sp. n. and t. petrochelidon sp. n. from the american cliff swallow petrochelidon pyrrhonota (vieillot), t. bochkovi sp. n. from the tree swallow tachycineta bicolor (vieillot), and t. cryptocaudata sp. n. and t. progne sp. n. from the ...201931715868
the neurogenomic transition from territory establishment to parenting in a territorial female songbird.the brain plays a critical role in upstream regulation of processes central to mating effort, parental effort, and self-maintenance. for seasonally breeding animals, the brain is likely mediating trade-offs among these processes within a short breeding season, yet research thus far has only explored neurogenomic changes from non-breeding to breeding states or select pathways (e.g., steroids) in male and/or lab-reared animals. here, we use rna-seq to explore neural plasticity in three behaviorall ...201931699031
differences in perceived predation risk associated with variation in relative size of extra-pair and within-pair offspring.extra-pair paternity (epp) is a widespread phenomenon in birds. researchers have long hypothesized that epp must confer a fitness advantage to extra-pair offspring (epo), but empirical support for this hypothesis is definitively mixed. this could be because genetic benefits of epp only exist in a subset of environmental contexts to which a population is exposed. from 2013 to 2015, we manipulated perceived predator density in a population of tree swallows (tachycineta bicolor) breeding in new yor ...202031677203
tissue-specific expression profiles and positive selection analysis in the tree swallow (tachycineta bicolor) using a de novo transcriptome assembly.tree swallows (tachycineta bicolor) are one of the most commonly studied wild birds in north america. they have advanced numerous research areas, including life history, physiology, and organismal responses to global change; however, transcriptomic resources are scarce. to further advance the utility of this system for biologists across disciplines, we generated a transcriptome for the tree swallow using six tissues (brain, blood, ovary, spleen, liver, and muscle) collected from breeding females ...201931676844
how research on female vertebrates contributes to an expanded challenge hypothesis.the bi-directional links between hormones and behavior have been a rich area of research for decades. theory on the evolution of testosterone (t) was greatly advanced by the challenge hypothesis, which presented a framework for understanding interspecific, seasonal, and social variation in t levels in males, and how they are shaped by the competing demands of parental care and male-male competition. female competition is also widespread in nature, although it is less clear whether or how the cha ...202031419407
the environmental and genetic determinants of chick telomere length in tree swallows (tachycineta bicolor).conditions during early life can have dramatic effects on adult characteristics and fitness. however, we still know little about the mechanisms that mediate these relationships. telomere shortening is one possibility. telomeres are long sequences of dna that protect the ends of chromosomes. they shorten naturally throughout an individual's life, and individuals with short telomeres tend to have poorer health and reduced survival. given this connection between telomere length (tl) and fitness, na ...201931380080
genome-wide variation in dna methylation is associated with stress resilience and plumage brightness in a wild bird.individuals often differ in their ability to cope with challenging environmental and social conditions. evidence from model systems suggests that patterns of dna methylation are associated with variation in coping ability. these associations could arise directly if methylation plays a role in controlling the physiological response to stressors by, among other things, regulating the release of glucocorticoids in response to challenges. alternatively, the association could arise indirectly if meth ...201931330076
stress resilience and the dynamic regulation of glucocorticoids.vertebrates respond to a diversity of stressors by rapidly elevating glucocorticoid (gc) levels. the changes in physiology and behavior triggered by this response can be crucial for surviving a variety of challenges. yet the same process that is invaluable in coping with immediate threats can also impose substantial damage over time. in addition to the pathological effects of long-term exposure to stress hormones, even relatively brief elevations can impair the expression of a variety of behavio ...201931168615
a range-wide domino effect and resetting of the annual cycle in a migratory songbird.latitudinal differences in timing of breeding are well documented but how such differences carry over to influence timing of events in the annual cycle of migratory birds is not well understood. we examined geographical variation in timing of events throughout the year using light-level geolocator tracking data from 133 migratory tree swallows ( tachycineta bicolor) originating from 12 north american breeding populations. a swallow's breeding latitude influenced timing of breeding, which then ca ...201930963870
perfluoroalkyl contaminant exposure and effects in tree swallows nesting at clarks marsh, oscoda, michigan, usa.a site in northeastern michigan, oscoda township, has some of the highest recorded exposure in birds to perfluorinated substances (pfass) in the united states. some egg and plasma concentrations at that location exceeded the lowest reproductive effect threshold established for two avian laboratory species. the objectives of this study were to determine whether there were reproductive effects or physiological responses in a model bird species, the tree swallow (tachycineta bicolor), associated wi ...201930955057
mercury exposure and altered parental nesting behavior in a wild songbird.methylmercury is a neurotoxin and endocrine disruptor and may impair avian reproduction directly through embryotoxicity or by altering parental care behaviors. we studied mercury exposure and incubation behavior of free-living tree swallows ( tachycineta bicolor) nesting in artificial nest boxes. using small temperature dataloggers, we measured incubation constancy (the proportion of each day the female spent incubating eggs), the number of incubation recesses taken per day, and the duration of ...201930924331
rainy springs linked to poor nestling growth in a declining avian aerial insectivore ( tachycineta bicolor).as species shift their ranges and phenology to cope with climate change, many are left without a ready supply of their preferred food source during critical life stages. food shortages are often assumed to be driven by reduced total food abundance, but here we propose that climate change may cause short-term food shortages for foraging specialists without affecting overall food availability. we frame this hypothesis around the special case of birds that forage on flying insects for whom effects ...201930862285
brief increases in corticosterone affect morphology, stress responses, and telomere length but not postfledging movements in a wild songbird.organisms are frequently exposed to challenges during development, such as poor weather and food shortage. such challenges can initiate the hormonal stress response, which involves secretion of glucocorticoids. although the hormonal stress response helps organisms deal with challenges, long-term exposure to high levels of glucocorticoids can have morphological, behavioral, and physiological consequences, especially during development. glucocorticoids are also associated with telomere shortening, ...201930840539
traffic noise exposure alters nestling physiology and telomere attrition through direct, but not maternal, effects in a free-living bird.anthropogenic impacts, such as noise pollution from transportation networks, can serve as stressors to some wildlife species. for example, increased exposure to traffic noise has been found to alter baseline and stress-induced corticosterone levels, reduce body condition and reproductive success, and increase telomere attrition in free-living birds. however, it remains unknown if alterations in nestling phenotype are due to direct or indirect effects of noise exposure. for example, indirect (mat ...201930796896
element concentrations in tree swallows (tachycineta bicolor) from the u.s. and binational great lakes areas of concern.selected elements were targeted in state remedial action plans as one group of chemicals affecting the beneficial use impairments of great lakes areas of concern (aocs). livers of nestling tree swallows, tachycineta bicolor, were harvested from 76 sites in the great lakes, which included multiple sites at 27 aocs and 12 reference sites from 2010 to 2015, and were analyzed for 21 elements. mercury concentrations were at background levels at all sites. elevated cadmium (cd) concentrations were ass ...201930734087
changes in thyroid function of nestling tree swallows (tachycineta bicolor) in relation to polycyclic aromatic compounds and other environmental stressors in the athabasca oil sands region.in the canadian athabasca oil sands region (aosr), nestling tree swallows (tachycineta bicolor) raised near mining-related activities accumulated greater concentrations of polycyclic aromatic compounds (pacs) that contributed to their poorer condition, growth, and reproductive success. here, we report changes in thyroid function of the same 14 day old (do) nestlings (n ≤ 68) at these mining-related sites (os1, os2) compared to reference nestlings (ref1), and in relation to multiple environmental ...201930530086
effects of blood parasite infection and innate immune genetic diversity on mating patterns in a passerine bird breeding in contrasted habitats.genetic diversity at immune genes and levels of parasitism are known to affect patterns of (dis)assortative mating in several species. heterozygote advantage and/or good genes should shape mate choice originating from pathogen/parasite-driven selection at immune genes. however, the stability of these associations, and whether they vary with environmental conditions, are still rarely documented. in this study, we describe mating patterns in a wild population of tree swallows (tachycineta bicolor) ...201830505637
solar-powered radio tags reveal patterns of post-fledging site visitation in adult and juvenile tree swallows tachycineta bicolor.the availability of small, lightweight tracking devices enhances our ability to study birds during mobile phases of their lives. tree swallows tachycineta bicolor, a model species of wild songbird, are well-studied during their breeding season; but our understanding of their biology at other times of the year, when they are not tied to the fixed location of a nest, is more limited. we developed a lightweight radio tag with no battery (solar nanotag) to study the movements of small animals, and w ...201830408052
baseline corticosterone does not reflect iridescent plumage traits in female tree swallows.the production of high quality secondary sexual traits can be constrained by trade-offs in the allocation of energy and nutrients with other metabolic activities, and is mediated by physiological processes. in birds, the factors influencing male plumage quality have been well studied; however, factors affecting female plumage quality are poorly understood. furthermore, it remains uncertain which physiological traits mediate the relationship between body condition and ornaments. in this three-yea ...201930392885
nest boxes increase reproductive output for tree swallows in a forest grassland matrix in central british columbia.secondary cavity-nesting birds depend on tree cavities for nesting and roosting, but many studies of these birds are conducted using nest boxes. implementation of effective conservation strategies for cavity-nesting species such as nest-site supplementation requires careful comparisons of fecundity and other vital rates for birds using both natural and artificial nest site types. we compared breeding phenology, clutch and brood sizes, and fledging success of tree swallows (tachycineta bicolor) n ...201830303975
tissue-specific gene regulation corresponds with seasonal plasticity in female testosterone.testosterone (t) is a sex steroid hormone that often varies seasonally and mediates trade-offs between territorial aggression and parental care. prior work has provided key insights into the 'top-down' hypothalamic control of this seasonal plasticity in t, yet mechanisms acting outside of the brain may also influence circulating t levels. we hypothesized that peripheral mechanisms may be especially critical for females, because peripheral regulation may mitigate the costs of systemically elevate ...201930291863
aquatic insects rich in omega-3 fatty acids drive breeding success in a widespread bird.ecologists studying bird foraging ecology have generally focused on food quantity over quality. emerging work suggests that food quality, in terms of highly unsaturated omega-3 fatty acids (hufa), can have equally important effects on performance. hufa, which are present in aquatic primary producers, are all but absent in vascular plants, and hufa content is also correspondingly higher in aquatic insects. here, we show that tree swallow (tachycineta bicolor) chicks rapidly accumulate hufa from f ...201830251301
effects of experimental chronic traffic noise exposure on adult and nestling corticosterone levels, and nestling body condition in a free-living bird.transportation noise affects urbanized, rural, and otherwise unaltered habitats. given expanding transportation networks, alterations in the acoustic landscapes experienced by animals are likely to be pervasive and persistent (i.e. chronic). it is important to understand if chronic noise exposure alters behavior and physiology in free-living animals, as it may result in long-lasting impacts, such as reduced reproductive success. here, we experimentally tested the effects of chronic traffic noise ...201830189211
endocrine-immune signaling as a predictor of survival: a prospective study in developing songbird chicks.immune function varies with an animal's endocrine physiology and energy reserves, as well as its abiotic and biotic environment. this context-dependency is thought to relate to adaptive trade-off resolution that varies from one context to the next; however, it is less clear how state- and environmentally-dependent differences in endocrine-immune signaling relate to survival in natural populations. we begin to address this question in a prospective study on a free-living passerine bird, the tree ...201830099034
the lingering impact of stress: brief acute glucocorticoid exposure has sustained, dose-dependent effects on reproduction.acutely stressful experiences can have profound and persistent effects on phenotype. across taxa, individuals differ remarkably in their susceptibility to stress. however, the mechanistic causes of enduring stress effects, and of individual differences in stress susceptibility, are poorly understood. here, we tested whether brief, acute increases in glucocorticoid hormones have persistent effects on phenotype, and whether effects differ according to the magnitude or duration of elevation. we use ...201830051820
standing variation and the capacity for change: are endocrine phenotypes more variable than other traits?circulating steroid hormone levels exhibit high variation both within and between individuals, leading some to hypothesize that these phenotypes are more variable than other morphological, physiological, and behavioral traits. this should have profound implications for the evolution of steroid signaling systems, but few studies have examined how endocrine variation compares to that of other traits or differs among populations. here we provide such an analysis by first exploring how variation in ...201829897574
testosterone production and social environment vary with breeding stage in a competitive female songbird.in many vertebrates, males increase circulating testosterone (t) levels in response to seasonal and social changes in competition. females are also capable of producing and responding to t, but the full extent to which they can elevate t across life history stages remains unclear. here we investigated t production during various breeding stages in female tree swallows (tachycineta bicolor), which face intense competition for nesting sites. we performed gnrh and saline injections and compared cha ...201829807035
reproductive and developmental changes in tree swallows (tachycineta bicolor) are influenced by multiple stressors, including polycyclic aromatic compounds, in the athabasca oil sands.mining in the athabasca oil sands region (aosr) has contributed extensively to increased exposure of wildlife to naturally occurring polycyclic aromatic compounds (pacs), yet little is known about the toxicity of pacs to wildlife in this region. we identified reproductive and developmental changes in tree swallows (tachycineta bicolor) breeding in close proximity to mining-related activities in the aosr, and determined these changes in relation to the birds' exposure and accumulation of 41 pacs ...201829684897
maternal immunization increases nestling energy expenditure, immune function, and fledging success in a passerine bird.female birds transfer maternally derived antibodies (matab) to their nestlings, via the egg yolk. these antibodies are thought to provide passive protection, and allow nestlings to avoid the costs associated with mounting an innate immune response. to test whether there is an energetic benefit to nestlings from receiving matab, we challenged adult female tree swallows (tachycineta bicolor) prior to clutch initiation with either lipopolysaccharide (lps) or saline (control). following hatching, on ...201829618466
annual variation in polychlorinated biphenyl (pcb) exposure in tree swallow (tachycineta bicolor) eggs and nestlings at great lakes restoration initiative (glri) study sites.tree swallow (tachycineta bicolor) eggs and nestlings were collected from 16 sites across the great lakes to quantify normal annual variation in total polychlorinated biphenyl (pcb) exposure and to validate the sample size choice in earlier work. a sample size of five eggs or five nestlings per site was adequate to quantify exposure to pcbs in tree swallows given the current exposure levels and variation. there was no difference in pcb exposure in two randomly selected sets of five eggs collecte ...201829550916
reproductive success and contaminant associations in tree swallows (tachycineta bicolor) used to assess a beneficial use impairment in u.s. and binational great lakes' areas of concern.during 2010-2014, tree swallow (tachycineta bicolor) reproductive success was monitored at 68 sites across all 5 great lakes, including 58 sites located within great lakes areas of concern (aocs) and 10 non-aocs. sample eggs were collected from tree swallow clutches and analyzed for contaminants including polychlorinated biphenyls (pcbs), dioxins and furans, polybrominated diphenyl ethers, and 34 other organic compounds. contaminant data were available for 360 of the clutches monitored. markov c ...201829524053
elevated exposure, uptake and accumulation of polycyclic aromatic hydrocarbons by nestling tree swallows (tachycineta bicolor) through multiple exposure routes in active mining-related areas of the athabasca oil sands region.in the athabasca oil sands (os) region, the exposure (by air, water, diet), uptake and deposition of polycyclic aromatic compounds (pacs), including parent and alkylated hydrocarbons (pahs) and dibenzothiophenes (dbts), was assessed in nestling tree swallows (tachycineta bicolor) at mining-related (os1, os2) and reference (ref) sites. the os sites did not receive oil-sands processed waters (ospw) and were ≥60km from the reference sites. most of the 42 pacs (≤98%) were detected in all matrices. s ...201829253773
waste-water treatment plants are implicated as an important source of flame retardants in insectivorous tree swallows (tachicyneta bicolor).wastewater treatment plants (wwtps) are an important source of anthropogenic chemicals, including organic flame retardants (frs). limited studies indicate birds can be exposed to frs by feeding from waters receiving wwtp effluent or in fields receiving biosolids. expanding on our earlier study, 47 legacy and 18 new fr contaminants were characterized in the eggs of insectivorous tree swallows (tachycineta bicolor) feeding in water bodies receiving effluent from two wwtps and compared to those fro ...201829248750
conversion efficiency of α-linolenic acid to omega-3 highly unsaturated fatty acids in aerial insectivore chicks.food availability and quality are both critical for growing young animals. in nature, swallows (tachycineta bicolor) and other aerial insectivores feed on both aquatic insects, which are rich in omega-3 highly unsaturated fatty acids (hufas), and terrestrial insects, which contain considerably lower amounts of omega-3 hufas. carnivorous mammals and fishes must obtain omega-3 hufas from their diet, as they have lost the capacity to convert the precursor omega-3 α-linolenic acid (ala) into omega-3 ...201829217628
environmental determinants of haemosporidian parasite prevalence in a declining population of tree swallows.the prevalence of vector-borne parasites such as haemosporidian species is influenced by several environmental factors. while the negative effects of parasitism on hosts are well documented, these can also be amplified by interactions with environmental stressors, many of which are anthropogenic. yet, we know little about the possible effects of anthropogenic perturbations on parasite prevalence. the goals of this study were to assess the prevalence and environmental determinants of haemosporidi ...201829166965
erod activity, chromosomal damage, and oxidative stress in response to contaminants exposure in tree swallow (tachycineta bicolor) nestlings from great lakes areas of concern.tree swallow, tachycineta bicolor, nestlings were collected from 60 sites in the great lakes, which included multiple sites within 27 areas of concern (aocs) and six sites not listed as aocs from 2010 to 2014. nestlings, approximately 12 days-of-age, were evaluated for ethoxyresorufin-o-dealkylase (erod) activity, chromosomal damage, and six measures of oxidative stress. data on each of these biomarkers were divided into four equal numbered groups from the highest to lowest values and the groups ...201729039061
effects of in ovo exposure to 3, 3',4,4'- tetrachlorobiphenyl (pcb 77) on heart development in tree swallow (tachycineta bicolor).tree swallow (tachycineta bicolor) eggs from two uncontaminated sites, patuxent research refuge (prr), md and cobleskill reservoir, ny were dosed with pcb 77 to evaluate effects on the developing cardiovascular system. to ensure embryonic viability, treatments were administered into the air cell at embryonic day (ed) 2.5 including: untreated (control), vehicle (filtered sterilized fatty acid mixture), 100 ng/g and 1,000 ng/g egg. eggs were dosed in the field with 0.2 μl per egg, returned to the ...201728767159
maternal transfer of mercury to songbird eggs.we evaluated the maternal transfer of mercury to eggs in songbirds, determined whether this relationship differed between songbird species, and developed equations for predicting mercury concentrations in eggs from maternal blood. we sampled blood and feathers from 44 house wren (troglodytes aedon) and 34 tree swallow (tachycineta bicolor) mothers and collected their full clutches (n = 476 eggs) within 3 days of clutch completion. additionally, we sampled blood and feathers from 53 tree swallow ...201728688298
heritable variation in circulating glucocorticoids and endocrine flexibility in a free-living songbird.phenotypic flexibility is a central way that organisms cope with challenging and changing environments. as endocrine signals mediate many phenotypic traits, heritable variation in hormone levels, or their context-dependent flexibility, could present an important target for selection. several studies have estimated the heritability of circulating glucocorticoid levels under acute stress conditions, but little is known about the potential for either baseline hormone levels or rapid endocrine flexi ...201728665031
integrated population models reveal local weather conditions are the key drivers of population dynamics in an aerial insectivore.changes to weather patterns under a warming climate are complex: while warmer temperatures are expected virtually worldwide, decreased mean precipitation is expected at mid-latitudes. migratory birds depend on broad-scale weather patterns to inform timing of movements, but may be more susceptible to local weather patterns during sedentary periods. we constructed bayesian integrated population models (ipms) to assess whether continental or local weather effects best explained population dynamics ...201728573381
natural selection on body size and laying date in the tree swallow.i measured natural selection on body size and laying date in a population of tree swallows (tachycineta bicolor) from 1986 to 1988. there was little evidence of selection on body size associated with overwinter survival. disruptive selection on tarsus length, associated with female reproductive success, was detected in one of three years. both repeatability and mother-daughter regression suggested that laying date was heritable. i found weak evidence of selection on laying date, associated with ...199128564184
wind and rain are the primary climate factors driving changing phenology of an aerial insectivore.while the ecological effects of climate change have been widely observed, most efforts to document these impacts in terrestrial systems have concentrated on the impacts of temperature. we used tree swallow (tachycineta bicolor) nest observations from two widely separated sites in central alaska to examine the aspects of climate affecting breeding phenology at the northern extent of this species' range. we found that two measures of breeding phenology, annual lay and hatch dates, are more strongl ...201728446701
seasonal patterns in reproductive success of temperate-breeding birds: experimental tests of the date and quality hypotheses.for organisms in seasonal environments, individuals that breed earlier in the season regularly attain higher fitness than their late-breeding counterparts. two primary hypotheses have been proposed to explain these patterns: the quality hypothesis contends that early breeders are of better phenotypic quality or breed on higher quality territories, whereas the date hypothesis predicts that seasonally declining reproductive success is a response to a seasonal deterioration in environmental quality ...201728405278
agricultural intensification is linked to constitutive innate immune function in a wild bird population.immunity represents an important defense mechanism against pathogens and is intimately linked to fitness. previous studies have found significant interindividual variation of immune responses in wild populations and have emphasized the importance of ecological factors in explaining this variability. a deterioration of environmental conditions, such as agricultural intensification, can modify resource availability and, as a result, alter immune functions. the aim of this study was to investigate ...201728277952
an evaluation of feather corticosterone as a biomarker of fitness and an ecologically relevant stressor during breeding in the wild.feather corticosterone (cort) levels are increasingly employed as biomarkers of environmental stress. however, it is unclear if feather cort levels reflect stress and/or workload in the wild. we investigated whether feather cort represents a biomarker of environmental stress and reproductive effort in tree swallows (tachycineta bicolor). specifically, we examined whether individual state and investment during reproduction could predict feather cort levels in subsequently moulted feathers and whe ...201728214946
patterns of diversity and spatial variability of β-defensin innate immune genes in a declining wild population of tree swallows.assessing the genetic variation and distribution of immune genes across heterogeneous environmental conditions in wild species is essential to further our understanding of the role of pathogen pressure and potential resistance or prevalence in hosts. researchers have recently investigated β-defensin genes in the wild, because their variability suggests that they may play an important role in innate host defense. this study investigated the variation occurring at 6 innate immune genes of the β-de ...201728186244
strategic adjustment of parental care in tree swallows: life-history trade-offs and the role of glucocorticoids.life-history theory predicts that optimal strategies of parental investment will depend on ecological and social factors, such as current brood value and offspring need. parental care strategies are also likely to be mediated in part by the hypothalamic-pituitary-adrenal axis and glucocorticoid hormones. here, we present an experiment in tree swallows (tachycineta bicolor), a biparental songbird with wide geographical distribution, asking whether parental care is strategically adjusted in respon ...201628083111
evolutionary potential of morphological traits across different life-history stages.despite accumulating examples of selection acting on heritable traits in the wild, predicted evolutionary responses are often different from observed phenotypic trends. various explanations have been suggested for these mismatches. these include within-individual changes across lifespan that can create important variation in genetic architecture of traits and selection acting on them, but also potential problems with the methodological approach used to predict evolutionary responses of traits. h ...201728000316
temporal overlap and repeatability of feather corticosterone levels: practical considerations for use as a biomarker.the measurement of corticosterone (cort) levels in feathers has recently become an appealing tool for the conservation toolbox, potentially providing a non-invasive, integrated measure of stress activity throughout the time of feather growth. however, because the mechanism of cort deposition, storage and stability in feathers is not fully understood, it is unclear how reliable this measure may be, especially when there is an extended interval between growth and feather collection. we compared co ...201627933163
an assessment of the reliability of quantitative genetics estimates in study systems with high rate of extra-pair reproduction and low recruitment.quantitative genetics approaches, and particularly animal models, are widely used to assess the genetic (co)variance of key fitness related traits and infer adaptive potential of wild populations. despite the importance of precision and accuracy of genetic variance estimates and their potential sensitivity to various ecological and population specific factors, their reliability is rarely tested explicitly. here, we used simulations and empirical data collected from an 11-year study on tree swall ...201727782118
conservation implications of a lack of relationship between baseline glucocorticoids and fitness in a wild passerine.the application of physiological measures to conservation monitoring has been gaining momentum and, while a suite of physiological traits are available to ascertain disturbance and condition in wildlife populations, glucocorticoids (i.e., gcs; cortisol and corticosterone) are the most heavily employed. the interpretation of gc levels as sensitive indicators of population change necessitates that gcs and metrics of population persistence are linked. however, the relationship between gcs and fitne ...201627763712
employing individual measures of baseline glucocorticoids as population-level conservation biomarkers: considering within-individual variation in a breeding passerine.labile physiological variables, such as stress hormones [i.e. glucocorticoids (gcs)], allow individuals to react to perturbations in their environment and may therefore reflect the effect of disturbances or positive conservation initiatives in advance of population-level demographic measures. although the application of gcs as conservation biomarkers has been of extensive interest, few studies have explicitly investigated whether baseline gc concentrations respond to disturbances consistently ac ...201627757239
omega-3 long-chain polyunsaturated fatty acids support aerial insectivore performance more than food quantity.once-abundant aerial insectivores, such as the tree swallow (tachycineta bicolor), have declined steadily in the past several decades, making it imperative to understand all aspects of their ecology. aerial insectivores forage on a mixture of aquatic and terrestrial insects that differ in fatty acid composition, specifically long-chain omega-3 polyunsaturated fatty acid (lcpufa) content. aquatic insects contain high levels of both lcpufa and their precursor omega-3 pufa, alpha-linolenic acid (al ...201627638210
organic contamination in tree swallow (tachycineta bicolor) nestlings at united states and binational great lakes areas of concern.contaminant exposure of tree swallows, tachycineta bicolor, nesting in 27 areas of concern (aocs) in the great lakes basin was assessed from 2010 to 2014 to assist managers and regulators in their assessments of great lakes aocs. contaminant concentrations in nestlings from aocs were compared with those in nestlings from nearby non-aoc sites. polychlorinated biphenyl (pcb) and polybrominated diphenyl ether concentrations in tree swallow nestling carcasses at 30% and 33% of aocs, respectively, we ...201727539913
do hormones, telomere lengths, and oxidative stress form an integrated phenotype? a case study in free-living tree swallows.synopsis all organisms must anticipate and balance energetic demands and available resources in order to maximize fitness. as hormones coordinate many interactions between an organism's internal condition and the external environment, they may be key in mediating the allocation of resources to meet these demands. however, given that individuals differ considerably in how they react to changes in energetic demand, we asked whether variations in endocrine traits also correspond with life history v ...201627252220
concentrations and spatial patterns of organic contaminants in tree swallow (tachycineta bicolor) eggs at united states and binational great lakes areas of concern, 2010-2015.tree swallows, tachycineta bicolor, were sampled across the great lakes basin in 2010 through 2015 to provide a system-wide assessment of current exposure to organic contaminants. the results provide information identified as critical by regulators to assess the "bird or animal deformity or reproductive problems" beneficial use impairment. eggs were collected from 69 sites across all 5 great lakes, including 27 areas of concern (aocs), some with multiple sites, and 10 sites not listed as an aoc. ...201627187748
a meta-analysis of relationships between polychlorinated biphenyl exposure and performance across studies of free-ranging tree swallows (tachycineta bicolor).habitats worldwide are increasingly being degraded by human activities, with environmental pollution representing a significant threat to species and ecosystems. the presence of persistent organic chemicals, such as polychlorinated biphenyls (pcbs), has generated concern. captive experiments and field studies have reported some evidence for detrimental effects of pcb exposure, but also significant variation across studies and species. here, i use a meta-analytical approach to combine findings ac ...201627152205
metals and metalloids in nestling tree swallows and their dietary items near oilsands mine operations in northern alberta.tree swallows (tachycineta bicolor) nesting near oilsands development in northern alberta are potentially exposed to elevated levels of metals. the objective of this study was to determine whether levels of metals and metalloid elements in dietary items and tissues of nestling tree swallows inhabiting areas near oilsands mine operations were higher compared to those of reference sites. we hypothesized that if there was increased, industry-related exposure to metals, it would be via the diet. we ...201627110982
experimental evidence that brighter males sire more extra-pair young in tree swallows.across taxa, extra-pair mating is widespread among socially monogamous species, but few studies have identified male ornamental traits associated with extra-pair mating success, and even fewer studies have experimentally manipulated male traits to determine whether they are related directly to paternity. as a consequence, there is little experimental evidence to support the widespread hypothesis that females choose more ornamented males as extra-pair mates. here, we conducted an experimental stu ...201627105297
life-history and phenotypic traits of insectivorous songbirds breeding on reclaimed mine land reveal ecological constraints.studies assessing impacts of industrial activities on wildlife typically examine population- or community-level responses. however, changes in measures such as species abundance or diversity are driven by cumulative responses of individuals to disturbance, and may take time to detect. quantifying individual responses could allow us to foresee and mitigate future population declines resulting from industrial activities, while providing ecologically informative indices to assess quality of reclaim ...201626930317
mercury concentrations in eggs of red-winged blackbirds and tree swallows breeding in voyageurs national park, minnesota.most investigations of the environmental effects of mercury (hg) have focused on aquatic food webs that include piscivorous fish or wildlife. however, recent investigations have shown that other species, including passerine songbirds, may also be at risk from exposure to methylmercury (mehg). we quantified hg concentrations in eggs of two species of songbirds, red-winged blackbirds (agelaius phoeniceus) and tree swallows (tachycineta bicolor), nesting in voyageurs national park, minnesota, usa. ...201626801652
multidimensional environmental influences on timing of breeding in a tree swallow population facing climate change.most phenological traits are extremely sensitive to current climate change, and advances in the timing of important life-history events have been observed in many species. in birds, phenotypic plasticity in response to temperature is thought to be the main mechanism underlying yearly adjustment in the timing of breeding. however, other factors could be important and interact to affect the levels of plastic responses between and/or within-individuals. here, we use long-term individual-based data ...201526640519
analysis of the optimal duration of behavioral observations based on an automated continuous monitoring system in tree swallows (tachycineta bicolor): is one hour good enough?studies of animal behavior often rely on human observation, which introduces a number of limitations on sampling. recent developments in automated logging of behaviors make it possible to circumvent some of these problems. once verified for efficacy and accuracy, these automated systems can be used to determine optimal sampling regimes for behavioral studies. here, we used a radio-frequency identification (rfid) system to quantify parental effort in a bi-parental songbird species: the tree swall ...201526559407
a hidden markov model for reconstructing animal paths from solar geolocation loggers using templates for light intensity.solar archival tags (henceforth called geolocators) are tracking devices deployed on animals to reconstruct their long-distance movements on the basis of locations inferred post hoc with reference to the geographical and seasonal variations in the timing and speeds of sunrise and sunset. the increased use of geolocators has created a need for analytical tools to produce accurate and objective estimates of migration routes that are explicit in their uncertainty about the position estimates.201526473033
weathering the storm: parental effort and experimental manipulation of stress hormones predict brood survival.unpredictable and inclement weather is increasing in strength and frequency, challenging organisms to respond adaptively. one way in which animals respond to environmental challenges is through the secretion of glucocorticoid stress hormones. these hormones mobilize energy stores and suppress non-essential physiological and behavioral processes until the challenge passes. to investigate the effects of glucocorticoids on reproductive decisions, we experimentally increased corticosterone levels (t ...201526438064
candidate gene-environment interactions and their relationships with timing of breeding in a wild bird population.monitoring and predicting evolutionary changes underlying current environmental modifications are complex challenges. recent approaches to achieve these objectives include assessing the genetic variation and effects of candidate genes on traits indicating adaptive potential. in birds, for example, short tandem repeat polymorphism at four candidate genes (clock, npas2, adcyap1, and creb1) has been linked to variation in phenological traits such as laying date and timing of migration. however, our ...201526380692
relationships among plumage coloration, blood selenium concentrations and immune responses of adult and nestling tree swallows.in a number of taxa, males and females both display ornaments that may be associated with individual quality and could be reliable signals to potential mates or rivals. we examined the iridescent blue/green back and white breast of adult tree swallows (tachycineta bicolor) to determine whether plumage reflectance is related to adult or offspring immune responses. we simultaneously addressed the influence of blood selenium levels and the interaction between blood selenium and plumage coloration o ...201526347556
tissue mercury concentrations and survival of tree swallow embryos, nestlings and young adult females on a contaminated site.tree swallows nesting on mercury-contaminated sites along the south river in virginia, usa were monitored for reproductive success. the bodies of nestlings found deceased in their nest boxes were collected, along with blood and feather samples from the adult parents and surviving siblings. we also measured hatching and fledging success of the clutches and the annual recapture rate of adults. we found that the body feathers of deceased nestlings contained significantly higher concentrations of me ...201526318205
assessing costs of carrying geolocators using feather corticosterone in two species of aerial insectivore.despite benefits of using light-sensitive geolocators to track animal movements and describe patterns of migratory connectivity, concerns have been raised about negative effects of these devices, particularly in small species of aerial insectivore. geolocators may act as handicaps that increase energetic expenditure, which could explain reported effects of geolocators on survival. we tested this 'energetic expenditure hypothesis' in 12 populations of tree swallows (tachycineta bicolor) and barn ...201526064659
low cost audiovisual playback and recording triggered by radio frequency identification using raspberry pi.playbacks of visual or audio stimuli to wild animals is a widely used experimental tool in behavioral ecology. in many cases, however, playback experiments are constrained by observer limitations such as the time observers can be present, or the accuracy of observation. these problems are particularly apparent when playbacks are triggered by specific events, such as performing a specific behavior, or are targeted to specific individuals. we developed a low-cost automated playback/recording syste ...201525870771
chromosomal damage and erod induction in tree swallows (tachycineta bicolor) along the upper mississippi river, minnesota, usa.the health of tree swallows, tachycineta bicolor, on the upper mississippi river (umr) was assessed in 2010 and 2011 using biomarkers at six sites downriver of minneapolis/st. paul, mn metropolitan area, a tributary into the umr, and a nearby lake. chromosomal damage was evaluated in nestling blood by measuring the coefficient of variation of dna content (dna cv) using flow cytometry. cytochrome p450 1a activity in nestling liver was measured using the ethoxyresorufin-o-dealkylase (erod) assay, ...201525777616
the effects of a remediated fly ash spill and weather conditions on reproductive success and offspring development in tree swallows.animals are exposed to natural and anthropogenic stressors during reproduction that may individually or interactively influence reproductive success and offspring development. we examined the effects of weather conditions, exposure to element contamination from a recently remediated fly ash spill, and the interaction between these factors on reproductive success and growth of tree swallows (tachycineta bicolor) across nine colonies. females breeding in colonies impacted by the spill transferred ...201525690609
effects of coal fly ash on tree swallow reproduction in watts bar reservoir, tennessee.coal-fly ash was released in unprecedented amounts (4.1 × 10(6) m(3) ) into the emory river from the tennessee valley authority kingston fossil plant on watts bar reservoir in tennessee. tree swallows were exposed to ash-related constituents at the ash release via their diet of emergent aquatic insects, whose larval forms can accumulate constituents from submerged river sediments. reproduction of tree swallow colonies was assessed over a 2-year period by evaluating whether 1) ash constituent con ...201525345977
detoxification, endocrine, and immune responses of tree swallow nestlings naturally exposed to air contaminants from the alberta oil sands.changes in environmental and wildlife health from contaminants in tailings water on the canadian oil sands have been well-studied; however, effects of air contaminants on wildlife health have not. a field study was conducted to assess biological costs of natural exposure to oil sands-related air emissions on birds. nest boxes for tree swallows (tachycineta bicolor) were erected at two sites; within 5 km of active oil sands mining and extraction, and ≥ 60 km south, at one reference site. passive ...201525240100
estimating dispersal among numerous sites using capture-recapture data.dispersal affects processes as diverse as habitat selection, population growth, and gene flow. inference about dispersal and its variation is thus crucial for assessing population and evolutionary dynamics. two approaches are generally used to estimate dispersal in free-ranging animals. first, multisite capture-recapture models estimate movement rates among sites while accounting for survival and detection probabilities. this approach, however, is limited in the number of sites that can be consi ...201425230481
incubation stage and polychlorinated biphenyl (pcb) congener patterns in an altricial and precocial bird species.the composition of polychlorinated biphenyl (pcb) congeners was compared between non-incubated and embryonated eggs of tree swallows (tachycineta bicolor) and little terns (sterna albifrons) to determine if measurable changes in pcb congeners occurred during the embryonic period. there was no indication of changes in pcb congener patterns over the incubation period in tree swallows in 1999 and 2000 at a site with very high pcb exposure or a site with more modest pcb exposure. additionally, conge ...201425213805
variation in riparian consumer diet composition and differential bioaccumulation by prey influence the risk of exposure to elements from a recently remediated fly ash spill.emerging aquatic insects play a key role in transporting aquatic nutrients and contaminants to riparian consumers. however, little is known about how within- and between-year variation in the diet or patterns of element bioaccumulation in emerging insect taxa may influence the risk of exposure to wildlife. during 2 breeding seasons, the composition of the diet of tree swallows (tachycineta bicolor) was examined at several colonies that were exposed to element contamination from a remediated coal ...201425113541
changes in polychlorinated biphenyl (pcb) exposure in tree swallows (tachycineta bicolor) nesting along the sheboygan river, wi, usa.exposure to polychlorinated biphenyls (pcbs) in tree swallow (tachycineta bicolor) eggs on the sheboygan river, wisconsin in the 1990s was higher at sites downstream (geometric means = 3.33-8.69 μg/g wet wt.) of the putative pcb source in sheboygan falls, wisconsin than it was above the source (1.24 μg/g) with the exposure declining as the distance downstream of the source increased. a similar pattern of declining exposure was present in the 2010s as well. although exposure to pcbs in eggs along ...201425056798
severe recent decrease of adult body mass in a declining insectivorous bird population.migratory bird species that feed on air-borne insects are experiencing widespread regional declines, but these remain poorly understood. agricultural intensification in the breeding range is often regarded as one of the main drivers of these declines. here, we tested the hypothesis that body mass in breeding individuals should reflect habitat quality in an aerial insectivore, the tree swallow (tachycineta bicolor), along a gradient of agricultural intensity. our dataset was collected over 7 year ...201424850929
contaminant exposure of birds nesting in green bay, wisconsin, usa.in earlier studies, elevated concentrations of polychlorinated biphenyl (pcb) and p,p'-dichlorodiphenyldichloroethylene (dde) were reported in double-crested cormorant (phalacrocorax auritus) eggs and tree swallow (tachycineta bicolor) eggs and nestlings collected from lower green bay (wi, usa) in 1994 and 1995 and black-crowned night-heron (nycticorax nycticorax) eggs collected in 1991. comparable samples collected in 2010 and 2011 indicated that concentrations of pcbs were 35%, 62%, 70%, and 8 ...201424733712
stable nitrogen isotopes of nestling tree swallows indicate exposure to different types of oil sands reclamation.tree swallows (tachycineta bicolor) inhabiting reclaimed wetlands on the oil sands in northern alberta are potentially exposed to elevated levels of oil sands constituents such as polycyclic aromatic compounds (pac) through diet. while increased detoxification enzyme activity as measured using 7-ethoxyresorufin o-deethylase in nestlings is a generally accepted indicator of exposure to oil sands constituents, there is no apparent method to detect dietary exposure specific to oil sands processed m ...201424627996
polybrominated diphenyl ethers and multiple stressors influence the reproduction of free-ranging tree swallows (tachycineta bicolor) nesting at wastewater treatment plants.reproductive success of birds is influenced by maternal factors, ambient temperatures, predation, food supply, and/or exposure to environmental contaminants e.g., flame retardants (frs). reproduction of tree swallows (tachycineta bicolor) was compared among waste water treatment plants (wwtps) and a reference reservoir in ontario, canada (2007-2010), to determine the importance of exposure to polybrominated diphenyl ether (pbdes) frs within a complex contaminant cocktail, relative to natural and ...201424291556
impacts of acid rainon aquatic birds.studies of toxicological and ecological effects of acidification on aquatic birds in europe and north america are reviewed. heavy metals are deposited by acid emissions, which also increase solubility and mobility of heavy metals in soil and water. aluminium is leached from soil and mobilized from lake sediments under acid conditions; it removes susceptible fish and invertebrate species and contaminates remaining invertebrates. it is not highly toxic to birds, but may interfere with their regula ...198924249190
interspecific differences in egg production affect egg trace element concentrations after a coal fly ash spill.in oviparous vertebrates, trace elements transfer from mother to offspring during egg production. for animals that produce eggs slowly, like turtles, the trace element concentration of each egg reflects an integration of dietary and stored accumulation over the duration of vitellogenesis. because turtles also produce eggs synchronously, all eggs within a clutch should exhibit uniform trace element concentrations. in contrast, for animals that produce eggs in sequence and primarily from current d ...201324180645
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