Publications

rapid effects of estrogens on behavior: environmental modulation and molecular mechanisms.	estradiol can modulate neural activity and behavior via both genomic and nongenomic mechanisms. environmental cues have a major impact on the relative importance of these signaling pathways with significant consequences for behavior. first we consider how photoperiod modulates nongenomic estrogen signaling on behavior. intriguingly, short days permit rapid effects of estrogens on aggression in both rodents and song sparrows. this highlights the importance of considering photoperiod as a variable ...	2014	24685383
pedigree error due to extra-pair reproduction substantially biases estimates of inbreeding depression.	understanding the evolutionary dynamics of inbreeding and inbreeding depression requires unbiased estimation of inbreeding depression across diverse mating systems. however, studies estimating inbreeding depression often measure inbreeding with error, for example, based on pedigree data derived from observed parental behavior that ignore paternity error stemming from multiple mating. such paternity error causes error in estimated coefficients of inbreeding (f) and reproductive success and could ...	2014	24171712
effects of corticosterone and dhea on doublecortin immunoreactivity in the song control system and hippocampus of adult song sparrows.	adult neuroplasticity is strongly influenced by steroids. in particular, corticosterone (cort) and dehydroepiandrosterone (dhea) can have opposing effects, where cort reduces while dhea increases neurogenesis and neuron recruitment. it has been previously shown that in adult male song sparrows, dhea treatment increases neuron recruitment throughout the telencephalon, including the lateral ventricular zone, while the effect of cort treatment is restricted to hvc, one of the song control regions. ...	2014	24123830
exposure pathways of anticoagulant rodenticides to nontarget wildlife.	second-generation anticoagulant rodenticides are widely reported to contaminate and poison nontarget wildlife, primarily predatory birds and mammals. exposure pathways, however, have not been well defined. here, we examined potential movement of rodenticides from deployment of bait to exposure of small mammals and other biota. at two adjacent working farms, we placed baits containing either brodifacoum or bromadiolone. we monitored movement of those compounds to the surrounding environment by co ...	2014	24048882
developmental programming of the hpa and hpg axes by early-life stress in male and female song sparrows.	variation in early environmental conditions can have long-term effects on physiology and behavior, a process referred to as developmental programming. in particular, exposure to early-life stressors can have long-term effects on regulation of the hypothalamic-pituitary-adrenal (hpa) and hypothalamic-pituitary-gonadal (hpg) axes. although these effects have been well documented in mammals, less is known about how early-life stress affects regulation of these endocrine systems in non-mammalian spe ...	2014	24291303
individual differences affect honest signalling in a songbird.	research in the past decade has established the existence of consistent individual differences or 'personality' in animals and their important role in many aspects of animal behaviour. at the same time, research on honest signalling of aggression has revealed that while some of the putative aggression signals are reliable, they are only imperfectly so. this study asks whether a significant portion of the variance in the aggression-signal regression may be explained by individual differences in s ...	2014	24307671
mammalian mesopredators on islands directly impact both terrestrial and marine communities.	medium-sized mammalian predators (i.e. mesopredators) on islands are known to have devastating effects on the abundance and diversity of terrestrial vertebrates. mesopredators are often highly omnivorous, and on islands, may have access not only to terrestrial prey, but to marine prey as well, though impacts of mammalian mesopredators on marine communities have rarely been considered. large apex predators are likely to be extirpated or absent on islands, implying a lack of top-down control of me ...	2014	25234377
genetic covariance between components of male reproductive success: within-pair vs. extra-pair paternity in song sparrows.	the evolutionary trajectories of reproductive systems, including both male and female multiple mating and hence polygyny and polyandry, are expected to depend on the additive genetic variances and covariances in and among components of male reproductive success achieved through different reproductive tactics. however, genetic covariances among key components of male reproductive success have not been estimated in wild populations. we used comprehensive paternity data from socially monogamous but ...	2014	25186454
distinguishing individual quality from habitat preference and quality in a territorial passerine.	theory predicts that animals breeding in heterogeneous landscapes preferentially occupy habitats likely to maximize individual fitness, but identifying those habitats has proved problematic. many studies develop metrics of habitat quality linked to site-specific reproductive output measured in successive years, but few separate the independent effects of individual "intrinsic quality" from those due solely to the attributes of the habitats themselves. in many populations, processes such as compe ...	2014	24669736
song complexity, song rate, and variation in the adrenocortical stress response in song sparrows (melospiza melodia).	physiological mechanisms that pleiotropically affect condition, life-history decisions, and fitness may covary with the expression of sexually selected ornaments. the adrenocortical stress response regulates energy balance, controls vertebrate responses to survival threats, and may divert energy expenditure away from investment in costly sexual displays. further, developmental stress may induce correlations between the stress response during adulthood and sexual signals that develop early in lif ...	2014	24650781
acute and chronic effects of an aromatase inhibitor on territorial aggression in breeding and nonbreeding male song sparrows.	many studies have demonstrated that male aggression is regulated by testosterone. the conversion of testosterone to estradiol by brain aromatase is also known to regulate male aggression in the breeding season. male song sparrows (melospiza melodia morphna) are territorial not only in the breeding season, but also in the nonbreeding season, when plasma testosterone and estradiol levels are basal. castration has no effect on nonbreeding aggression. in contrast, chronic (10 day) aromatase inhibito ...	2014	11016791
the fitness consequences of honesty: under-signalers have a survival advantage in song sparrows.	how honest or reliable signaling can evolve and be maintained has been a major question in evolutionary biology. the question is especially puzzling for a particular class of signals used in aggressive interactions: threat signals. here, we report a study on song sparrows (melospiza melodia) in which we assayed males with playbacks on their territories to quantify their aggressiveness (flights and close proximity) and aggressive signaling levels (rates of soft song, a close-range signal reliably ...	2015	26573880
non-invasive administration of 17β-estradiol rapidly increases aggressive behavior in non-breeding, but not breeding, male song sparrows.	17β-estradiol (e2) acts in the brain via genomic and non-genomic mechanisms to influence physiology and behavior. there is seasonal plasticity in the mechanisms by which e2 activates aggression, and non-genomic mechanisms appear to predominate during the non-breeding season. male song sparrows (melospiza melodia) display e2-dependent territorial aggression throughout the year. field studies show that song sparrow aggression during a territorial intrusion is similar in the non-breeding and breedi ...	2015	25483754
quantifying inbreeding avoidance through extra-pair reproduction.	extra-pair reproduction is widely hypothesized to allow females to avoid inbreeding with related socially paired males. consequently, numerous field studies have tested the key predictions that extra-pair offspring are less inbred than females' alternative within-pair offspring, and that the probability of extra-pair reproduction increases with a female's relatedness to her socially paired male. however, such studies rarely measure inbreeding or relatedness sufficiently precisely to detect subtl ...	2015	25346331
resolving the conundrum of inbreeding depression but no inbreeding avoidance: estimating sex-specific selection on inbreeding by song sparrows (melospiza melodia).	inbreeding avoidance among interacting females and males is not always observed despite inbreeding depression in offspring fitness, creating an apparent "inbreeding paradox." this paradox could be resolved if selection against inbreeding was in fact weak, despite inbreeding depression. however, the net magnitude and direction of selection on the degree to which females and males inbreed by pairing with relatives has not been explicitly estimated. we used long-term pedigree data to estimate pheno ...	2015	26420476
a microsatellite-based linkage map for song sparrows (melospiza melodia).	although linkage maps are important tools in evolutionary biology, their availability for wild populations is limited. the population of song sparrows (melospiza melodia) on mandarte island, canada, is among the more intensively studied wild animal populations. its long-term pedigree data, together with extensive genetic sampling, have allowed the study of a range of questions in evolutionary biology and ecology. however, the availability of genetic markers has been limited. we here describe 191 ...	2015	25865627
rapid effects of estradiol on aggression in birds and mice: the fast and the furious.	across invertebrates and vertebrates, steroids are potent signaling molecules that affect nearly every cell in the organism, including cells of the nervous system. historically, researchers have focused on the genomic (or "nuclear-initiated") effects of steroids. however, all classes of steroids also have rapid non-genomic (or "membrane-initiated") effects, although there is far less basic knowledge of these non-genomic effects. in particular, steroids synthesized in the brain ("neurosteroids") ...	2015	25980562
double decomposition: decomposing the variance in subcomponents of male extra-pair reproductive success.	1. extra-pair reproductive success (eprs) is a key component of male fitness in socially monogamous systems and could cause selection on female extra-pair reproduction if extra-pair offspring (epo) inherit high value for eprs from their successful extra-pair fathers. however, eprs is itself a composite trait that can be fully decomposed into subcomponents of variation, each of which can be further decomposed into genetic and environmental variances. however, such decompositions have not been imp ...	2015	25976301
genetic divergence of an avian endemic on the californian channel islands.	the californian channel islands are near-shore islands with high levels of endemism, but extensive habitat loss has contributed to the decline or extinction of several endemic taxa. a key parameter for understanding patterns of endemism and demography in island populations is the magnitude of inter-island dispersal. this paper estimates the extent of migration and genetic differentiation in three extant and two extinct populations of channel island song sparrows (melospiza melodia graminea). int ...	2015	26308717
across time and space: effects of urbanization on corticosterone and body condition vary over multiple years in song sparrows (melospiza melodia).	animals inhabiting urban areas must simultaneously cope with the unique challenges presented by this novel habitat type while exploiting the distinctive opportunities it offers. the costs and benefits of urban living are often assumed to be consistent across time, but may in fact vary depending on the habitat features influencing them. here we examine the glucocorticoid levels and body condition of song sparrows (melospiza melodia) resident at urban and rural sites over four consecutive years to ...	2015	25678475
demographic mechanisms of inbreeding adjustment through extra-pair reproduction.	one hypothesis explaining extra-pair reproduction is that socially monogamous females mate with extra-pair males to adjust the coefficient of inbreeding (f) of extra-pair offspring (epo) relative to that of within-pair offspring (wpo) they would produce with their socially paired male. such adjustment of offspring f requires non-random extra-pair reproduction with respect to relatedness, which is in turn often assumed to require some mechanism of explicit pre-copulatory or post-copulatory kin di ...	2015	25645743
early-life stress has sex-specific effects on immune function in adult song sparrows.	multiple components of the immune system are modulated by environmental factors, including exposure to stressors. in particular, chronic stressors can impair development of the immune system, leading to alterations in immune function in adulthood. while these effects have been well established in mammals, less is known about how developmental stress modulates immunity in nonmammalian species. we determined the long-term effects of exposure to early-life stressors on immunity in song sparrows inc ...	2015	25730273
seasonal variation in group size is related to seasonal variation in neuropeptide receptor density.	in many species, seasonal variation in grouping behavior is widespread, with shifts towards territoriality in the breeding season and grouping in the winter. compared to the hormonal and neural mechanisms of seasonal territorial aggression, the mechanisms that promote seasonal grouping have received little attention. we collected brains in spring and winter from wild-caught males of two species of emberizid sparrows that seasonally flock (the field sparrow, spizella pusilla, and the dark-eyed ju ...	2016	27788503
breeding dispersal by birds in a dynamic urban ecosystem.	changes in land cover during urbanization profoundly affect the diversity of bird communities, but the demographic mechanisms affecting diversity are poorly known. we advance such understanding by documenting how urbanization influences breeding dispersal-the annual movement of territorial adults-of six songbird species in the seattle, wa, usa metropolitan area. we color-banded adults and mapped the centers of their annual breeding activities from 2000-2010 to obtain 504 consecutive movements by ...	2016	28030559
chemical composition of preen wax reflects major histocompatibility complex similarity in songbirds.	in jawed vertebrates, genes of the major histocompatibility complex (mhc) play a key role in immunity by encoding cell-surface proteins that recognize and bind non-self antigens. high variability at mhc suggests that these loci may also function in social signalling such as mate choice and kin recognition. this requires that mhc genotype covaries with some perceptible phenotypic trait. in mammals and fish, mhc is signalled chemically through volatile and non-volatile peptide odour cues, facilita ...	2016	27807264
dehydroepiandrosterone heightens aggression and increases androgen receptor and aromatase mrna expression in the brain of a male songbird.	dehydroepiandrosterone (dhea) is a testosterone/oestrogen precursor and known modulator of vertebrate aggression. male song sparrows (melospiza melodia morphna) show high aggression during breeding and nonbreeding life-history stages when circulating dhea levels are high, and low aggression during molt when dhea levels are low. we previously showed that androgen receptor and aromatase mrna expression are higher during breeding and/or nonbreeding in brain regions associated with reproductive and ...	2016	27805753
correction to 'agonistic urban birds: elevated territorial aggression of urban song sparrows is individually consistent within a breeding period'.		2016	27903781
song sparrows melospiza melodia have a home-field advantage in defending against sympatric malarial parasites.	hosts and parasites interact on both evolutionary and ecological timescales. the outcome of these interactions, specifically whether hosts are more resistant to their local parasites (sympatric) than to parasites from another location (allopatric), is likely to affect the spread of infectious disease and the fitness consequences of host dispersal. we conducted a cross-infection experiment to determine whether song sparrows (melospiza melodia) have an advantage in dealing with sympatric parasites ...	2016	27853596
direct and indirect genetic and fine-scale location effects on breeding date in song sparrows.	quantifying direct and indirect genetic effects of interacting females and males on variation in jointly expressed life-history traits is central to predicting microevolutionary dynamics. however, accurately estimating sex-specific additive genetic variances in such traits remains difficult in wild populations, especially if related individuals inhabit similar fine-scale environments. breeding date is a key life-history trait that responds to environmental phenology and mediates individual and p ...	2016	27448623
testosterone, migration distance, and migratory timing in song sparrows melospiza melodia.	in seasonally migratory animals, migration distance often varies substantially within populations such that individuals breeding at the same site may overwinter different distances from the breeding grounds. shorter migration may allow earlier return to the breeding grounds, which may be particularly advantageous to males competing to acquire a breeding territory. however, little is known about potential mechanisms that may mediate migration distance. we investigated naturally-occurring variatio ...	2016	27534598
agonistic urban birds: elevated territorial aggression of urban song sparrows is individually consistent within a breeding period.	urban birds often more vigorously defend their territories during simulated intrusions than do their rural counterparts, but the factors responsible remain unclear. to address this issue, we investigated whether the disparity in territorial aggression of urban and rural male song sparrows, melospiza melodia, is individually consistent within a breeding period. additionally, to better understand the physiological and ecological factors underlying this behavioural difference, we examined whether t ...	2016	27330174
variation in parent-offspring kinship in socially monogamous systems with extra-pair reproduction and inbreeding.	female extra-pair reproduction in socially monogamous systems is predicted to cause cuckolded socially-paired males to conditionally reduce paternal care, causing selection against extra-pair reproduction and underlying polyandry. however, existing models and empirical studies have not explicitly considered that cuckolded males might be related to their socially-paired female and/or to her extra-pair mate, and therefore be related to extra-pair offspring that they did not sire but could rear. se ...	2016	27174154
is pairing with a relative heritable? estimating female and male genetic contributions to the degree of biparental inbreeding in song sparrows (melospiza melodia).	the degree of inbreeding expressed within populations can profoundly shape evolutionary dynamics. the degree to which individuals inbreed is frequently assumed to evolve in response to selection, for example, resulting from inbreeding depression. such evolutionary responses require additive genetic variance (va) in the degree to which individuals inbreed. however, the magnitude of va in the degree of biparental inbreeding has never been estimated. we devised a quantitative genetic model to estim ...	2016	27172593
rapid effects of an aggressive interaction on dehydroepiandrosterone, testosterone and oestradiol levels in the male song sparrow brain: a seasonal comparison.	across vertebrates, aggression is robustly expressed during the breeding season when circulating testosterone is elevated, and testosterone activates aggression either directly or after aromatisation into 17β-oestradiol (e2 ) in the brain. in some species, such as the song sparrow, aggressive behaviour is also expressed at high levels during the nonbreeding season, when circulating testosterone is non-detectable. at this time, the androgen precursor dehydroepiandrosterone (dhea) is metabolised w ...	2016	26648568
age and years to death disparately influence reproductive allocation in a short-lived bird.	theory predicts that reproduction will change as individuals near the end of their lives by either increasing reproductive allocation (terminal allocation hypothesis) or decreasing allocation (senescence hypothesis) toward the end of life. although senescence has received more support, few studies examine how both age and years to death influence late-life reproduction. we used a 37-yr study of song sparrows (melospiza melodia) to ask how age and years to death influenced reproductive allocation ...	2017	28387020
pedigree-based inbreeding coefficient explains more variation in fitness than heterozygosity at 160 microsatellites in a wild bird population.	although the pedigree-based inbreeding coefficient f predicts the expected proportion of an individual's genome that is identical-by-descent (ibd), heterozygosity at genetic markers captures mendelian sampling variation and thereby provides an estimate of realized ibd. realized ibd should hence explain more variation in fitness than their pedigree-based expectations, but how many markers are required to achieve this in practice remains poorly understood. we use extensive pedigree and life-histor ...	2017	28250184
population differences at mhc do not explain enhanced resistance of song sparrows to local parasites.	infectious disease represents an emerging threat to natural populations, particularly when hosts are more susceptible to novel parasites (allopatric) than to parasites from the local area (sympatric). this pattern could arise through evolutionary processes (host populations become adapted to their local parasites and genetically differentiated from other populations at immune-related loci) and/or through ecological interactions (host individuals develop resistance to local parasites through prev ...	2017	27940472
individual fitness and the effects of a changing climate on the cessation and length of the breeding period using a 34-year study of a temperate songbird.	studies of the phenological responses of animals to climate change typically emphasize the initiation of breeding, even though climatic effects on the cessation and length of the breeding period may be as or more influential of fitness. we quantified links between climate, the cessation and length of the breeding period, and individual survival and reproduction using a 34 year study of a resident song sparrow (melospiza melodia) population subject to dramatic variation in climate. we show that t ...	2017	28869682
male song sparrows have elevated testosterone in response to neighbors versus strangers.	upon hearing a conspecific signal, animals must assess their relationship with the signaller and respond appropriately. territorial animals usually respond more aggressively to strangers than neighbors in a phenomenon known as the "dear enemy effect". this phenomenon likely evolved because strangers represent a threat to an animal's territory tenure and parentage, whereas neighbors only represent a threat to an animal's parentage because they already possess a territory (providing territory boun ...	2017	28434901
linking phenological events in migratory passerines with a changing climate: 50 years in the laurel highlands of pennsylvania.	advanced timing of both seasonal migration and reproduction in birds has been strongly associated with a warming climate for many bird species. phenological responses to climate linking these stages may ultimately impact fitness. we analyzed five decades of banding data from 17 migratory bird species to investigate 1) how spring arrival related to timing of breeding, 2) if the interval between arrival and breeding has changed with increasing spring temperatures, and 3) whether arrival timing or ...	2017	28403152
song learning and cognitive ability are not consistently related in a songbird.	learned aspects of song have been hypothesized to signal cognitive ability in songbirds. we tested this hypothesis in hand-reared song sparrows (melospiza melodia) that were tutored with playback of adult songs during the critical period for song learning. the songs developed by the 19 male subjects were compared to the model songs to produce two measures of song learning: the proportion of notes copied from models and the average spectrogram cross-correlation between copied notes and model note ...	2017	27844219
aggressive behaviours track transitions in seasonal phenotypes of female siberian hamsters.	seasonally breeding animals exhibit profound physiological and behavioural responses to changes in ambient day length (photoperiod), including changes in reproductive function and territorial aggression.species where aggression persists when gonads are regressed and circulating levels of gonadal hormones are low, such as siberian hamsters (phodopus sungorus) and song sparrows (melospiza melodia), challenge the well-established framework that gonadal hormones are important mediators of aggression ...	2017	28757672
postbreeding elevational movements of western songbirds in northern california and southern oregon.	migratory species employ a variety of strategies to meet energetic demands of postbreeding molt. as such, at least a few species of western neotropical migrants are known to undergo short-distance upslope movements to locations where adults molt body and flight feathers (altitudinal molt migration). given inherent difficulties in measuring subtle movements of birds occurring in western mountains, we believe that altitudinal molt migration may be a common yet poorly documented phenomenon. to exam ...	2017	29043031
immune profiles vary seasonally, but are not significantly related to migration distance or natal dispersal, in a migratory songbird.	a central tenet of ecoimmunology is that an organism's environment shapes its optimal investment in immunity. for example, the benefits of acquired (relatively pathogen specific) versus innate (nonspecific) immune defenses are thought to vary with the risk of encountering familiar versus unfamiliar pathogens. because pathogen communities vary geographically, individuals that travel farther during seasonal migration or natal dispersal are predicted to have higher exposure to novel pathogens, and ...	2017	29356443
birdsong signals individual diversity at the major histocompatibility complex.	the major histocompatibility complex (mhc) plays a key role in vertebrate immunity, and pathogen-mediated selection often favours certain allelic combinations. assessing potential mates' mhc profiles may provide receivers with genetic benefits (identifying mhc-compatible mates and producing optimally diverse offspring) and/or material benefits (identifying optimally diverse mates capable of high parental investment). oscine songbirds learn songs during early life, such that song repertoire conte ...	2017	29118240
fear affects parental care, which predicts juvenile survival and exacerbates the total cost of fear on demography.	fear itself (perceived predation risk) can affect wildlife demography, but the cumulative impact of fear on population dynamics is not well understood. parental care is arguably what most distinguishes birds and mammals from other taxa, yet only one experiment on wildlife has tested fear effects on parental food provisioning and the repercussions this has for the survival of dependent offspring, and only during early-stage care. we tested the effect of fear on late-stage parental care of mobile ...	2018	29030965
territorial aggression in urban and rural song sparrows is correlated with corticosterone, but not testosterone.	urban songbirds of several species more vigorously defend their territories in response to conspecific song playback than do their rural counterparts, but the hormonal basis of this behavioral difference is unclear. it is well established in vertebrates that both testosterone and corticosterone affect the intensity of territoriality. previous studies have found no evidence that initial (i.e., immediately following territorial challenge, but prior to restraint) plasma testosterone accounts for th ...	2018	29166572
is there indirect selection on female extra-pair reproduction through cross-sex genetic correlations with male reproductive fitness?	one key hypothesis explaining the evolution and persistence of polyandry, and resulting female extra-pair reproduction in socially monogamous systems, is that female propensity for extra-pair reproduction is positively genetically correlated with male reproductive fitness and consequently experiences positive cross-sex indirect selection. however, key genetic correlations have rarely been estimated, especially in free-living populations experiencing natural (co)variation in reproductive strategi ...	2018	30283673
sex-specific additive genetic variances and correlations for fitness in a song sparrow (melospiza melodia) population subject to natural immigration and inbreeding.	quantifying sex-specific additive genetic variance (va ) in fitness, and the cross-sex genetic correlation (ra ), is prerequisite to predicting evolutionary dynamics and the magnitude of sexual conflict. further, quantifying va and ra in underlying fitness components, and genetic consequences of immigration and resulting gene flow, is required to identify mechanisms that maintain va in fitness. however, these key parameters have rarely been estimated in wild populations experiencing natural envi ...	2018	30101430
individual repeatability and heritability of divorce in a wild population.	understanding micro-evolutionary responses of mating systems to contemporary selection requires estimating sex-specific additive genetic variances and cross-sex genetic covariances in key reproductive strategy traits. one key trait comprises the occurrence of divorce versus mate fidelity across sequential reproductive attempts. if divorce represents an evolving behavioural strategy that responds to selection it must have non-zero individual repeatability and heritability, but quantitative estima ...	2018	29899127
purifying selection in the toll-like receptors of song sparrows melospiza melodia.	variation in immune gene sequences is known to influence resistance to infectious diseases and parasites, and hence survival and mate choice, across animal taxa. toll-like receptors (tlrs) comprise one essential gene family in the vertebrate innate immune system and recognize evolutionarily conserved structures from all major microorganism classes. however, the causes and consequences of tlr variation in passerine birds remain largely unexplored. we examined 7 tlr genes in song sparrows (melospi ...	2018	29893971
husbandry of wild-caught song sparrows (melospiza melodia).	conservation and research efforts occasionally rely upon bringing wild animals into human care to establish breeding programs and to understand their biology. wild-caught birds may have husbandry requirements that differ from captive-reared animals due, in part, to their social development in the wild and potential exposure to novel pathogens. we developed husbandry techniques to minimize stress and monitor health in a population of wild-caught song sparrows (melospiza melodia). we describe encl ...	2018	29740869
the consequences of polyandry for sibship structures, distributions of relationships and relatedness, and potential for inbreeding in a wild population.	the evolutionary benefits of simultaneous polyandry (female multiple mating within a single reproductive event) remain elusive. one potential benefit could arise if polyandry alters sibship structures and consequent relationships and relatedness among females' descendants, thereby intrinsically reducing future inbreeding risk (the indirect inbreeding avoidance hypothesis). however such effects have not been quantified in naturally complex mating systems that also encompass iteroparity, overlappi ...	2018	29693437
exposing migratory sparrows to plasmodium suggests costs of resistance, not necessarily of infection itself.	migratory birds move through multiple habitats and encounter a diverse suite of parasites. this raises concern over migrants' role in transporting infectious disease between breeding and wintering grounds, and along migratory flyways. trade-offs between flight and immune defenses could interfere with infected individuals' migratory timing and success, potentially affecting infection dynamics. however, experimental evidence that parasitic infection affects migratory preparation or timing remains ...	2018	29570956
no evidence of inbreeding depression in sperm performance traits in wild song sparrows.	inbreeding is widely hypothesized to shape mating systems and population persistence, but such effects will depend on which traits show inbreeding depression. population and evolutionary consequences could be substantial if inbreeding decreases sperm performance and hence decreases male fertilization success and female fertility. however, the magnitude of inbreeding depression in sperm performance traits has rarely been estimated in wild populations experiencing natural variation in inbreeding. ...	2018	29435258
elevated mercury in blood and feathers of breeding marsh birds along the contaminated lower penobscot river, maine, usa.	mercury (hg) concentrations in the blood and feathers of five species of migratory marsh birds, nelson's sparrow (ammodramus nelson subvirgatus), song sparrow (melospiiza melodia), swamp sparrow (melospiza geogiana), red-winged blackbird (agelaius phoeniceus), and virginia rail (rallus limicola), breeding in marshes along the lower penobscot river, maine, far exceeded reference concentrations, exceeded concentrations associated with reproductive health, and are the highest hg concentrations repo ...	2018	29710654
demographic consequences of invasion by a native, controphic competitor to an insular bird population.	species invasions and range shifts can lead to novel competitive interactions between historically resident and colonizing species, but the demographic consequences of such interactions remain controversial. we present results from field experiments and 45 years of demographic monitoring to test the hypothesis that the colonization of mandarte is., bc, canada, by fox sparrows (passerella iliaca) caused the long-term decline of the resident population of song sparrows (melospiza melodia). several ...	2018	29500488
rapid effects of 17β-estradiol on aggressive behavior in songbirds: environmental and genetic influences.	contribution to special issue on fast effects of steroids. 17β-estradiol (e2) has numerous rapid effects on the brain and behavior. this review focuses on the rapid effects of e2 on aggression, an important social behavior, in songbirds. first, we highlight the contributions of studies on song sparrows, which reveal that seasonal changes in the environment profoundly influence the capacity of e2 to rapidly alter aggressive behavior. e2 administration to male song sparrows increases aggression wi ...	2018	29605636
avian malaria co-infections confound infectivity and vector competence assays of plasmodium homopolare.	currently, there are very few studies of avian malaria that investigate relationships among the host-vector-parasite triad concomitantly. in the current study, we experimentally measured the vector competence of several culex mosquitoes for a newly described avian malaria parasite, plasmodium homopolare. song sparrow (melospiza melodia) blood infected with a low p. homopolare parasitemia was inoculated into a naïve domestic canary (serinus canaria forma domestica). within 5 to 10 days post infec ...	2018	29845414
influence of the agricultural conservation easement program wetland practices on winter occupancy of passerellidae sparrows and avian species richness.	wetlands enrolled in the agricultural conservation easement program (acep) are established as a means of restoring wetland ecosystems and wildlife habitat on private, agricultural land. in west virginia, usa, acep wetlands have never been evaluated to determine how they function as wildlife habitat in comparison to other available wetland habitat in the state. we measured the wintering occupancy of passerellidae species and apparent avian species richness on acep wetlands and a set of reference ...	2019	30677050
wax ester composition of songbird preen oil varies seasonally and differs between sexes, ages, and populations.	chemical signaling has been well studied in invertebrates and mammals but less so in birds, due to the longstanding misconception that olfaction is unimportant or even non-existent in this taxon. however, recent findings suggest that olfaction plays an important role in avian mate choice and reproductive behavior, similar to other taxa. the leading candidate source for compounds involved in avian chemical communication is preen oil, a complex mixture secreted from the uropygial gland. preen oil ...	2019	30456558
gut parasite levels are associated with severity of response to immune challenge in a wild songbird.	life history trade-offs have been posited to shape wild animals' immune responses against microparasites (e.g., bacteria, viruses). however, coinfection with gut helminths may bias immune phenotypes away from inflammatory responses and could be another mechanism underlying variation in immune responses. we examined how the magnitude of a common and costly response to microparasites, the acute phase response (apr), varied with helminth coinfection at both the individual and the population levels ...	2019	29999463
multi-modal communication: song sparrows increase signal redundancy in noise.	although the effects of anthropogenic noise on animal communication have been studied widely, most research on the effect of noise in communication has focused on signals in a single modality. consequently, how multi-modal communication is affected by anthropogenic noise is relatively poorly understood. here, we ask whether song sparrows (melospiza melodia) show evidence of plasticity in response to noise in two aggressive signals in acoustic and visual modalities. we test two hypotheses: (i) th ...	2019	31662064
individuals' expected genetic contributions to future generations, reproductive value, and short-term metrics of fitness in free-living song sparrows (melospiza melodia).	appropriately defining and enumerating "fitness" is fundamental to explaining and predicting evolutionary dynamics. yet, general theoretical concepts of fitness are often hard to translate into quantities that can be measured in wild populations experiencing complex environmental, demographic, genetic, and selective variation. although the "fittest" entities might be widely understood to be those that ultimately leave most descendants at some future time, such long-term legacies can rarely be me ...	2019	31171983
measurement of 11-dehydrocorticosterone in mice, rats and songbirds: effects of age, sex and stress.	glucocorticoids (gcs) are secreted into the blood by the adrenal glands and are also locally-produced by organs such as the lymphoid organs (bone marrow, thymus, and spleen). corticosterone is the primary circulating gc in many species, including mice, rats and birds. within lymphoid organs, corticosterone can be locally produced from the inactive metabolite, 11-dehydrocorticosterone (dhc). however, very little is known about endogenous dhc levels, and no immunoassays are currently available to ...	2019	31145891
"balancing" balancing selection? assortative mating at the major histocompatibility complex despite molecular signatures of balancing selection.	in vertebrate animals, genes of the major histocompatibility complex (mhc) determine the set of pathogens to which an individual's adaptive immune system can respond. mhc genes are extraordinarily polymorphic, often showing elevated nonsynonymous relative to synonymous sequence variation and sharing presumably ancient polymorphisms between lineages. these patterns likely reflect pathogen-mediated balancing selection, for example, rare-allele or heterozygote advantage. such selection is often rei ...	2019	31110668
neuropeptide y and orexin immunoreactivity in the sparrow brain coincide with seasonal changes in energy balance and steroids.	the transition between the breeding and nonbreeding states is often marked by a shift in energy balance. despite this well-known shift in energy balance, little work has explored seasonal differences in the orexigenic neuropeptides that regulate food intake in wild animals. here we tested the hypothesis that free-living male song sparrows (melospiza melodia) show seasonal changes in energetic state, circulating steroids, and both neuropeptide y (npy) and orexin (ox) immunoreactivity. nonbreeding ...	2019	30225913
testing predictions of inclusive fitness theory in inbreeding relatives with biparental care.	inclusive fitness theory predicts that parental care will vary with relatedness between potentially caring parents and offspring, potentially shaping mating system evolution. systems with extra-pair paternity (epp), and hence variable parent-brood relatedness, provide valuable opportunities to test this prediction. however, existing theoretical and empirical studies assume that a focal male is either an offspring's father with no inbreeding, or is completely unrelated. we highlight that this sim ...	2019	31795864
development of the corticosterone stress response differs among passerine species.	glucocorticoids are steroid hormones which increase dramatically in response to a physical or perceived stressor. however, developing young of altricial species typically have a damped glucocorticoid stress response. the developmental hypothesis posits that the physiological stress response should develop concurrently with an individual's ability to respond to a challenge. the dampened response may benefit an organism, as chronic exposure to glucocorticoids can have short- and long-term detrimen ...	2020	32027877
bird species involved in west nile virus epidemiological cycle in southern québec.	despite many studies on west nile virus (wnv) in the us, including the reservoir role of bird species and the summer shifts of the culex mosquito, feeding from birds to mammals, there have been few equivalent studies in the neighboring regions of canada where wnv is endemic. here, a priority list of bird species likely involved in wnv transmission in the greater montréal area is constructed by combining three sources of data: (i) from wnv surveillance in wild birds (2002-2015); (ii) blood meal a ...	2020	32585999
genomic differentiation and local adaptation on a microgeographic scale in a resident songbird.	elucidating forces capable of driving species diversification in the face of gene flow remains a key goal in evolutionary biology. song sparrows, melospiza melodia, occur as 25 subspecies in diverse habitats across north america, are among the continent's most widespread vertebrate species, and are exemplary of many highly variable species for which the conservation of locally adapted populations may be critical to their range-wide persistence. we focus here on six morphologically distinct subsp ...	2020	32978972
social factors in bird-song development: learning to sing with friends and rivals.	laboratory studies have revealed that social factors are key in bird-song learning. nevertheless, little is known about how or why birds choose the songs they do learn from the many they will hear under natural conditions. we focus on various theories concerning social song learning that have been offered to date, with special attention paid to two axes of social factors. first, does song learning occur via direct interaction of the young bird with song tutors, or via social eavesdropping by the ...	2020	32820427
recent immigrants alter the quantitative genetic architecture of paternity in song sparrows.	quantifying additive genetic variances and cross-sex covariances in reproductive traits, and identifying processes that shape and maintain such (co)variances, is central to understanding the evolutionary dynamics of reproductive systems. gene flow resulting from among-population dispersal could substantially alter additive genetic variances and covariances in key traits in recipient populations, thereby altering forms of sexual conflict, indirect selection, and evolutionary responses. however, t ...	2020	32313688
perceived wintering latitude determines timing of song output in a migratory bird.	migratory bird populations frequently consist of individuals that overwinter variable distances from the breeding site. seasonal changes in photoperiod, which varies with latitude, underlie seasonal changes in singing frequency in birds. therefore, migratory populations that consist of individuals that overwinter at different latitudes with large overwintering ranges could experience within-population variation in seasonal production of song. to test the influence of overwintering latitude on in ...	2020	32015840
song sparrows do not discriminate between their own song and stranger song.	bird song is socially learned. during song learning, the bird's hearing its own vocalization is important for normal development of song. whether bird's own song is represented and recognized as a special category in adult birds, however, is unclear. if birds respond differently to their own songs when these are played back to them, this would be evidence for auditory self-recognition. to test this possibility, we presented song sparrow males (melospiza melodia) playbacks of their own songs or s ...	2020	32561233
effects of low-density urbanization on genetic structure in the song sparrow.	urbanization fragments landscapes and can impede the movement of organisms through their environment, which can decrease population connectivity. reduction in connectivity influences gene flow and allele frequencies, and can lead to a reduction in genetic diversity and the fixation of certain alleles, with potential negative effects for populations. previous studies have detected effects of urbanization on genetic diversity and structure in terrestrial animals living in landscapes that vary in t ...	2020	32530950
birds suppress pests in corn but release them in soybean crops within a mixed prairie/agriculture system.	birds provide ecosystem services (pest control) in many agroecosystems and have neutral or negative ecological effects (disservices) in others. large-scale, conventional row crop agriculture is extremely widespread globally, yet few studies of bird effects take place in these agroecosystems. we studied indirect effects of insectivorous birds on corn and soybean crops in fields adjacent to a prairie in illinois (usa). we hypothesized that prairie birds would forage for arthropods in adjacent crop ...	2020	32476673
food stress, but not experimental exposure to mercury, affects songbird preen oil composition.	mercury is a global pollutant and potent neurotoxic metal. its most toxic and bioavailable form, methylmercury, can have both lethal and sublethal effects on wildlife. in birds, methylmercury exposure can disrupt behavior, hormones, the neuroendocrine system, and feather integrity. lipid-rich tissues and secretions may be particularly susceptible to disruption by lipophilic contaminants such as methylmercury. one such substance is feather preen oil, a waxy secretion of the uropygial gland that s ...	2020	32036507
brain activity underlying american crow processing of encounters with dead conspecifics.	animals utilize a variety of auditory and visual cues to navigate the landscape of fear. for some species, including corvids, dead conspecifics appear to act as one such visual cue of danger, and prompt alarm calling by attending conspecifics. which brain regions mediate responses to dead conspecifics, and how this compares to other threats, has so far only been speculative. using 18f-fluorodeoxyglucose positron emission tomography (fdg-pet) we contrast the metabolic response to visual and audit ...	2020	32035868
a high-quality genome assembly of the north american song sparrow, melospiza melodia.	the song sparrow, melospiza melodia, is one of the most widely distributed species of songbirds found in north america. it has been used in a wide range of behavioral and ecological studies. this species' pronounced morphological and behavioral diversity across populations makes it a favorable candidate in several areas of biomedical research. we have generated a high-quality de novo genome assembly of m. melodia using illumina short read sequences from genomic and in vitro proximity-ligation li ...	2020	32075855