Publications

antibody response of wild birds to natural infection with alphaviruses.	from 1986 to 1990, we conducted our second longitudinal study in the central (upstate) new york (cny) area on the wild avian hosts of eastern equine encephalomyelitis (eee) virus. field-collecting methods mirrored a study conducted from 1978 to 1980 at the same endemic focus. over the 5-yr study period, we captured 6,296 birds representing 99 species and took 4,174 blood samples from representatives of 83 species. gray catbirds, song sparrows, and veerys were the three dominant species captured ...	2004	15605649
reservoir competence of native north american birds for the lyme disease spirochete, borrelia burgdorfieri.	reservoir competence for the lyme disease spirochete, borrelia burgdorferi, was tested for six species of native north american birds: american robin, gray catbird, brown thrasher, eastern towhee, song sparrow, and northern cardinal. wild birds collected by mist netting on fire island, ny, were held in a field laboratory in cages over water and locally collected larval ticks were placed on the birds, harvested from the water after engorgement, and tested for infection by direct fluorescentantibo ...	2005	15962798
variable effects of climate change on six species of north american birds.	many recent studies have shown that birds are advancing their laying date in response to long-term increases in spring temperatures. these studies have been conducted primarily in europe and at local scales. if climate change is a large-scale phenomenon, then we should see responses at larger scales and in other regions. we examined the effects of long-term temperature change on the laying dates and clutch sizes of six ecologically diverse species of north american birds using 50 years of nest r ...	2005	16096849
neural responses to aggressive challenge correlate with behavior in nonbreeding sparrows.	the present study was conducted on captive male song sparrows (melospiza melodia) during the nonbreeding season in order to (1) examine fos and zenk responses of basal forebrain sites to simulated territorial intrusion and (2) determine how those responses relate to aggression. numerous forebrain areas showed significant fos and zenk responses to simulated territorial intrusion, and in several areas of the hypothalamus and lateral septum, these responses were negatively correlated with aggressiv ...	2005	16189485
seasonal gonadal recrudescence in song sparrows: response to temperature cues.	day length predicts changing of seasons at mid-latitudes, but additional environmental cues (e.g., temperature, rainfall) give more precise information about timing of food peaks critical for offspring survival. we tested the effects of temperature on seasonal reproductive development of male song sparrows (melospiza melodia morphna) from two populations: the western washington coast (3 m) and cascade mountains (500-1220 m). previous work has shown that the timing of gonadal recrudescence can di ...	2005	16061070
sexual selection: the importance of long-term fitness measures.	new results from a 20-year study of free-living song sparrows confirm that attractive males contribute more offspring than less attractive males. they also reveal that the offspring of preferred males produce more descendents themselves. females prefer males with a large song repertoire, which further work shows is a condition-dependent indicator of male quality.	2005	15886090
northwestern song sparrow populations show genetic effects of sequential colonization.	two genetic consequences are often considered evidence of a founder effect: substantial loss in genetic diversity and rapid divergence between source and founder populations. single-step founder events have been studied for these effects, but with mixed results, causing continued controversy over the role of founder events in divergence. experiments of serial bottlenecks have shown losses of diversity, increased divergence, and rapid behavioural changes possibly leading to reproductive isolation ...	2005	15813781
fitness correlates of song repertoire size in free-living song sparrows (melospiza melodia).	models of sexual selection propose that exaggerated secondary sexual ornaments indicate a male's own fitness and the fitness of his offspring. these hypotheses have rarely been thoroughly tested in free-living individuals because overall fitness, as opposed to fitness components, is difficult to measure. we used 20 years of data from song sparrows (melospiza melodia) inhabiting mandarte island, british columbia, canada, to test whether a male's song repertoire size, a secondary sexual trait, pre ...	2005	15729661
seasonal change in neuron size and spacing but not neuronal recruitment in a basal ganglia nucleus in the avian song control system.	neural plasticity in the song control system of seasonally breeding songbirds accompanies seasonal changes in singing behavior. the volume of area x, a song control nucleus that forms a portion of the avian basal ganglia, is 75% larger in the spring than it is in the fall. the neuronal basis of the seasonal plasticity in area x is largely unknown, however. we examined neuronal attributes of area x in wild adult male song sparrows (melospiza melodia) captured during the spring and the fall after ...	2005	15593375
long-term maternal effect on offspring immune response in song sparrows melospiza melodia.	knowledge of the causes of variation in host immunity to parasitic infection and the time-scales over which variation persists, is integral to predicting the evolutionary and epidemiological consequences of host-parasite interactions. it is clear that offspring immunity can be influenced by parental immune experience, for example, reflecting transfer of antibodies from mothers to young offspring. however, it is less clear whether such parental effects persist or have functional consequences over ...	2006	17148291
molecular identification of blood-meal sources in culiseta melanura and culiseta morsitans from an endemic focus of eastern equine encephalitis virus in new york.	eastern equine encephalitis (eee) virus perpetuates in an enzootic cycle involving ornithophilic mosquito vectors, principally culiseta melanura (coquillett) and avian amplification hosts. to better understand the role of cs. melanura and culiseta morsitans (theobald) in the epizootiology of eee virus, we collected blood-fed mosquitoes between 31 may and 15 october 2004 at two sites associated with an eee virus focus in central new york and identified the source of vertebrate blood by nucleotide ...	2006	17172382
food and predators affect egg production in song sparrows.	although the possibility that food and predators may interact in limiting avian populations has long been recognized, there have been few attempts to test this experimentally in the field. we conducted a manipulative food addition experiment on the demography of song sparrows (melospiza melodia) across sites that varied in predator abundance, near victoria, british columbia, canada, over three consecutive breeding seasons. we previously showed that food and predators had interactive effects on a ...	2006	17089655
interactive effects of environmental stress and inbreeding on reproductive traits in a wild bird population.	1. conservation biologists are concerned about the interactive effects of environmental stress and inbreeding because such interactions could affect the dynamics and extinction risk of small and isolated populations, but few studies have tested for these interactions in nature. 2. we used data from the long-term population study of song sparrows melospiza melodia on mandarte island to examine the joint effects of inbreeding and environmental stress on four fitness traits that are known to be aff ...	2006	17032373
inbreeding: when parents transmit more than genes.	inbreeding in wild populations can have devastating effects on fitness, but the genetic causes should not be transmitted across generations. a new study of song sparrows has revealed a parent-offspring resemblance for inbreeding, resulting from population structuring, with important implications for understanding the genetic causes of phenotypic variation in wild populations.	2006	16979552
early nutritional stress impairs development of a song-control brain region in both male and female juvenile song sparrows (melospiza melodia) at the onset of song learning.	birdsong is a sexually selected trait and is often viewed as an indicator of male quality. the developmental stress hypothesis proposes a model by which song could be an indicator; the time during early development, when birds learn complex songs and/or local variants of song, is of rapid development and nutritional stress. birds that cope best with this stress may better learn to produce the most effective songs. the developmental stress hypothesis predicts that early food restriction should im ...	2006	16959649
seasonal modulation of sickness behavior in free-living northwestern song sparrows (melospiza melodia morphna).	a variety of vertebrate species modulate immune function on a seasonal basis to cope with seasonal energy deficits and competing life-history demands, such as reproduction. most studies to date have focused upon seasonal variation of cellular and humoral immunity, while neglecting behavioral responses to infection. these behavioral strategies are collectively termed sickness behaviors and are hypothesized to divert energy away from normal activities to combat and overcome infection. sickness beh ...	2006	16888055
distributed and selective auditory representation of song repertoires in the avian song system.	for many songbirds, the vocal repertoire constitutes acoustically distinct songs that are flexibly used in various behavioral contexts. to investigate how these different vocalizations are represented in the song neural system, we presented multiple song stimuli while performing extracellular recording in nucleus hvc in adult male song sparrows melospiza melodia, a species known for its complex vocal repertoire and territorial use of song. we observed robust auditory responses to natural song st ...	2006	16885516
experience with songs in adulthood reduces song-induced gene expression in songbird auditory forebrain.	male songbirds learn to produce song within a limited phase early in life; however they continue to learn to recognize songs in adulthood. studies looking at zenk activation after exposure to songs learned early in life for song production and songs learned in adulthood show opposite patterns of activation, suggesting distinct neural mechanisms may be involved in these two forms of learning. in this study, we look at ieg zenk activation in auditory regions ncm and cmm of song sparrows (melospiza ...	2006	16807000
testosterone and aggression: berthold, birds and beyond.	berthold's classic study of domesticated roosters in 1849 demonstrated that testicular secretions are necessary for the normal expression of aggressive behaviour. although this conclusion is undoubtedly correct, field studies of wild songbirds have yielded important modifications and limitations of berthold's original hypothesis. for example, studies of the north american song sparrow (melospiza melodia) during the breeding season reveal that not only does testosterone increase aggression, but a ...	2006	16774503
intrinsic parent-offspring correlation in inbreeding level in a song sparrow (melospiza melodia) population open to immigration.	the extent to which offspring resemble their parents in genotype and phenotype underpins patterns of genetic and phenotypic variation, selection, and evolution in natural populations. genetic and phenotypic resemblance can clearly result from additive genetic variance and can be shaped by nongenetic parental and common environmental influences. in contrast, there is no straightforward expectation that inbreeding coefficient (f), a nonadditive component of genetic "quality," should be correlated ...	2006	16685634
combined food and predator effects on songbird nest survival and annual reproductive success: results from a bi-factorial experiment.	food and predators have traditionally been viewed as mutually exclusive alternatives when considering factors affecting animal populations. this has led to long controversies such as whether annual reproductive success in songbirds is primarily a function of food-restricted production or predator-induced loss. recent studies on both birds and mammals suggest many of these controversies may be resolved by considering the combined effects of food and predators. we conducted a 2x2 manipulative food ...	2006	16425048
breeding experience and population density affect the ability of a songbird to respond to future climate variation.	predicting how populations respond to climate change requires an understanding of whether individuals or cohorts within populations vary in their response to climate variation. we used mixed-effects models on a song sparrow (melospiza melodia) population in british columbia, canada, to examine differences among females and cohorts in their average breeding date and breeding date plasticity in response to the el niño southern oscillation. climatic variables, age and population density were strong ...	2007	17698488
song repertoire size varies with hvc volume and is indicative of male quality in song sparrows (melospiza melodia).	complex birdsong is a classic example of a sexually selected ornamental trait. in many species, females prefer males with large song repertoires, possibly because repertoire size is limited by the size of song control nuclei which reflect developmental success. we investigated whether song repertoire size was indicative of brain area and male quality in song sparrows (melospiza melodia) by determining if repertoire size was related to the volume of song control nucleus hvc, as well as several mo ...	2007	17567560
seasonal changes in intrinsic electrophysiological activity of song control neurons in wild song sparrows.	song behavior and its underlying neural substrate can change seasonally in adult songbirds. to test whether environmental cues induce seasonal changes in electrophysiological characteristics of song control neurons, we measured in vitro intrinsic neuronal activity in the song control nucleus ra of adult male song sparrows (melospiza melodia) in both the fall non-breeding and spring breeding seasons. we found that ra neurons in spring-captured birds show a more than threefold increase in spontane ...	2007	17440735
inbreeding effects on immune response in free-living song sparrows (melospiza melodia).	the consequences of inbreeding for host immunity to parasitic infection have broad implications for the evolutionary and dynamical impacts of parasites on populations where inbreeding occurs. to rigorously assess the magnitude and the prevalence of inbreeding effects on immunity, multiple components of host immune response should be related to inbreeding coefficient (f) in free-living individuals. we used a pedigreed, free-living population of song sparrows (melospiza melodia) to test whether in ...	2007	17254994
do stable isotopes reflect nutritional stress? results from a laboratory experiment on song sparrows.	stable isotope analysis is an increasingly valuable tool in ecological studies and shows promise as a measure of nutritional stress in wild animals. thus far, however, the only studies on endotherms that have conclusively shown changes in delta(15)n and delta(13)c values in response to nutritional stress were conducted on fasting animals and animals growing under extreme levels of food restriction. we conducted a laboratory experiment to test whether delta(15)n and delta(13)c values provide a ge ...	2007	17102993
secondary sexual ornamentation and non-additive genetic benefits of female mate choice.	ornamental secondary sexual traits are hypothesized to evolve in response to directional mating preferences for more ornamented mates. such mating preferences may themselves evolve partly because ornamentation indicates an individual's additive genetic quality (good genes). while mate choice can also confer non-additive genetic benefits (compatible genes), the identity of the most 'compatible' mate is assumed to depend on the choosy individual's own genotype. it is therefore unclear how choice f ...	2007	17374595
does feeding on infected mosquitoes (diptera: culicidae) enhance the role of song sparrows in the transmission of arboviruses in california?	song sparrows, melopiza melodia, inoculated subcutaneously with either western equine encephalomyelitis virus (family togaviridae, genus alphavirus, weev) or west nile virus (family flaviviridae, genus flavivirus, wnv) developed elevated viremias, and they were considered to be competent experimental hosts for both viruses. however, birds that ingested from three to 20 mosquitoes containing comparable amounts of either weev or wnv failed to become infected, indicating limited oral susceptibility ...	2007	17427703
ability of transstadially infected ixodes pacificus (acari: ixodidae) to transmit west nile virus to song sparrows or western fence lizards.	the hypothesis that ixodes pacificus cooley & kohls (acari: ixodidae) may serve as a reservoir and vector of west nile virus (family flaviviridae, genus flavivirus, wnv) in california was tested by determining the ability of this tick species to become infected with the ny99 strain of wnv while feeding on viremic song sparrows, to maintain the infection transstadially, and then to transmit wnv to recipient naive song sparrows and western fence lizards during the nymphal stage. the percentage of ...	2007	17427704
sheep in wolf's clothing: host nestling vocalizations resemble their cowbird competitor's.	nestlings of many avian brood parasites are virtuosos at mimicking host nestling vocalizations, which, like egg mimicry, presumably ensures acceptance by host parents. having been accepted, parasitic nestlings then often exaggerate the aspects of the host's display to increase parental care. host nestlings may, in turn, exaggerate their vocalizations to keep up with the parasite, though this possibility has not been evaluated. we experimentally parasitized song sparrow (melospiza melodia) nests ...	2008	18252675
the effects of contemporary processes in maintaining the genetic structure of western song sparrows (melospiza melodia).	historic events and contemporary processes work in concert to create and maintain geographically partitioned variation and are instrumental in the generation of biodiversity. we sought to gain a better understanding of how contemporary processes such as movement and isolation influence the genetic structure of widely distributed vagile species such as birds. song sparrows (melospiza melodia) in western north america provide a natural system for examining the genetics of populations that have dif ...	2008	18461086
local song elements indicate local genotypes and predict physiological condition in song sparrows melospiza melodia.	geographical variation in birdsong is taxonomically widespread and behaviourally salient, with females often preferring local over non-local song. however, the benefits associated with this preference remain poorly understood. one potential explanation is that song may reflect a male's place of origin and thus allow females to obtain genes well adapted to the local environment. we studied naturally occurring variation in the degree to which the elements of a male's song repertoire matched those ...	2008	18331976
dehydroepiandrosterone and corticosterone are regulated by season and acute stress in a wild songbird: jugular versus brachial plasma.	stress has well-known effects on adrenal glucocorticoid secretion, and chronic elevation of glucocorticoids can have detrimental effects on the brain. dehydroepiandrosterone (dhea), an androgen precursor synthesized in the adrenal glands or the brain itself, has anti-glucocorticoid properties, but little is known about the role of dhea in the stress response, particularly in the brain. here, we measured the effects of acute restraint on circulating corticosterone (cort) and dhea levels in wild s ...	2008	18276756
individual phenotype, kinship, and the occurrence of inbreeding in song sparrows.	inbreeding load, a key parameter in evolutionary ecology, is frequently estimated by regressing fitness (or related traits) on inbreeding coefficient across population members. this approach assumes that inbreeding occurs randomly with respect to an individual's intrinsic ability to produce fit offspring; estimated loads might otherwise be biased by covariation between inbreeding and individual quality. this assumption, however, is rarely validated. we tested whether, in free-living song sparrow ...	2008	18248635
testing evolutionary models of senescence in a natural population: age and inbreeding effects on fitness components in song sparrows.	mutation accumulation (ma) and antagonistic pleiotropy (ap) have each been hypothesized to explain the evolution of 'senescence' or deteriorating fitness in old age. these hypotheses make contrasting predictions concerning age dependence in inbreeding depression in traits that show senescence. inbreeding depression is predicted to increase with age under ma but not under ap, suggesting one empirical means by which the two can be distinguished. we use pedigree and life-history data from free-livi ...	2008	18211879
combined effects of dhea and fadrozole on aggression and neural vip immunoreactivity in the non-breeding male song sparrow.	the male song sparrow, melospiza melodia morphna, shows high levels of aggression in its non-breeding season, concomitant with basal levels of circulating testosterone (t) and estradiol (e(2)). however, administration of fadrozole, an aromatase inhibitor, decreases non-breeding aggression in the field. circulating levels of dehydroepiandrosterone (dhea), an androgen/estrogen precursor, correspond to the seasonal expression of aggression in this species, with high levels in the breeding and non-b ...	2008	18036596
seasonal differences of gene expression profiles in song sparrow (melospiza melodia) hypothalamus in relation to territorial aggression.	male song sparrows (melospiza melodia) are territorial year-round; however, neuroendocrine responses to simulated territorial intrusion (sti) differ between breeding (spring) and non-breeding seasons (autumn). in spring, exposure to sti leads to increases in luteinizing hormone and testosterone, but not in autumn. these observations suggest that there are fundamental differences in the mechanisms driving neuroendocrine responses to sti between seasons. microarrays, spotted with est cdna clones o ...	2009	19997634
corticosterone and dehydroepiandrosterone in songbird plasma and brain: effects of season and acute stress.	prolonged increases in plasma glucocorticoids can exacerbate neurodegeneration. in rats, these neurodegenerative effects can be reduced by dehydroepiandrosterone (dhea), an androgen precursor with anti-glucocorticoid actions. in song sparrows, season and acute restraint stress affect circulating levels of corticosterone and dhea, and the effects of stress differ in plasma collected from the brachial and jugular veins. jugular plasma is an indirect index of the neural steroidal milieu. here, we d ...	2009	19473242
estimating the annual number of breeding attempts from breeding dates using mixture models.	well-established statistical methods exist to estimate variation in a number of key demographic rates from field data, including life-history transition probabilities and reproductive success per attempt. however, our understanding of the processes underlying population change remains incomplete without knowing the number of reproductive attempts individuals make annually; this is a key demographic rate for which we have no satisfactory method of estimating. using census data to estimate this pa ...	2009	19725863
stress, song and survival in sparrows.	the stress response--increases in circulating glucocorticoids following a stressor--is typically considered adaptive, but few studies address the fitness consequences of individual variation in stress response. generally, due to negative consequences of prolonged elevation of glucocorticoids, animals should have a transient stress response just sufficient to cope with the stressor. in rodents, stress responsiveness is affected by early developmental experience, and hyper-responsiveness to stress ...	2009	19605381
food-supplementing parents reduces their sons' song repertoire size.	food-supplemented parents typically produce more offspring, as numerous experiments on vertebrate populations have shown. 'propagule' (egg or neonate) size and parental care may also be affected, with implications concerning the adult quality of offspring, although few experiments have addressed whether food-supplementing one generation affects adult quality in the next. we conducted a food supplementation experiment on song sparrows (melospiza melodia) and tested whether song repertoire size, a ...	2009	19457889
mate choice for nonadditive genetic benefits and the maintenance of genetic diversity in song sparrows.	the lek paradox asserts that strong directional selection via female choice should deplete additive genetic variation in fitness and consequently any benefit to females expressing the preference. recently, we have provided a novel resolution to the paradox by showing that nonadditive genetic effects such as overdominance can be inherited from parent to offspring, and populations with females that express a mating preference for outbred males maintain higher genetic variation than populations wit ...	2009	19032502
detection of lyme disease spirochete, borrelia burgdorferi sensu lato, including three novel genotypes in ticks (acari: ixodidae) collected from songbirds (passeriformes) across canada.	lyme disease is reported across canada, but pinpointing the source of infection has been problematic. in this three-year, bird-tick-pathogen study (2004-2006), 366 ticks representing 12 species were collected from 151 songbirds (31 passerine species/subspecies) at 16 locations canada-wide. of the 167 ticks/pools tested, 19 (11.4%) were infected with borrelia burgdorferi sensu lato (s.l.). sequencing of the rrf-rrl intergenic spacer gene revealed four borrelia genotypes: b. burgdorferi sensu stri ...	2010	20618658
food supplementation leads to bottom-up and top-down food-host-parasite interactions.	1. food-prey-predator interactions may involve both 'bottom-up' and 'top-down' processes. conventionally, food-host-parasite interactions have been seen as governed solely from the 'bottom-up', i.e. well-fed hosts can better resist parasites and so suffer less parasitism. recent studies on diverse endo- and ecto-parasites increasingly highlight that well-fed hosts provide parasites with a better resource base, and so may be more likely to be parasitized. 2. brood parasites exploit host parental ...	2010	20646123
corticosterone and dehydroepiandrosterone have opposing effects on adult neuroplasticity in the avian song control system.	chronic elevations in glucocorticoids can decrease the production and survival of new cells in the adult brain. in rat hippocampus, supraphysiological doses of dehydroepiandrosterone (dhea; a sex steroid precursor synthesized in the gonads, adrenals, and brain) have antiglucocorticoid properties. with male song sparrows (melospiza melodia), we examined the effects of physiological doses of corticosterone, the primary circulating glucocorticoid in birds, and dhea on adult neuroplasticity. we trea ...	2010	20653028
seasonal changes in aromatase and androgen receptor, but not estrogen receptor mrna expression in the brain of the free-living male song sparrow, melospiza melodia morphna.	free-living male song sparrows experience three annually repeating life history stages associated with differential expression of sex steroid-dependent reproductive and aggressive behavior. in the breeding stage, they display reproductive and aggressive behavior and have elevated circulating testosterone levels. during molt, males show little or no aggression and no reproductive behavior, and have basal levels of circulating testosterone. in the non-breeding stage, they display high levels of ag ...	2010	20653036
juvenile sparrows preferentially eavesdrop on adult song interactions.	recent research has demonstrated that bird song learning is influenced by social factors, but so far has been unable to isolate the particular social variables central to the learning process. here we test the hypothesis that eavesdropping on singing interactions of adults is a key social event in song learning by birds. in a field experiment, we compared the response of juvenile male song sparrows (melospiza melodia) to simulated adult counter-singing versus simulated solo singing. we used radi ...	2010	19846461
the role of androgen receptors in regulating territorial aggression in male song sparrows.	this paper examines the role that androgen receptors (ars) play in modulating aggressive behavior in male song sparrows, melospiza melodia morphna. song sparrows are seasonally breeding, territorial birds that maintain year-round territories with male-female pair bonds formed during the spring breeding season. plasma testosterone levels peak as territories are established and mates acquired. in late summer, testosterone levels fall and remain basal during the non-breeding season. we examined the ...	2010	19799905
inbreeding coefficient and heterozygosity-fitness correlations in unhatched and hatched song sparrow nestmates.	heterozygosity-fitness correlations use molecular measures of heterozygosity as proxy estimates of individual inbreeding coefficients (f) to examine relationships between inbreeding and fitness traits. heterozygosity-fitness correlations partly depend on the assumption that individual heterozygosity and f are strongly and negatively correlated. although theory predicts that this relationship will be strongest when mean f and variance in f are high, few studies of heterozygosity-fitness correlati ...	2010	20854411
comprehensive paternity assignment: genotype, spatial location and social status in song sparrows, melospiza melodia.	comprehensive, accurate paternity assignment is critical to answering numerous questions in evolutionary ecology. yet, most studies of species with extra-pair paternity (epp) fail to assign sires to all offspring. common limitations include incomplete and biased sampling of offspring and males, particularly with respect to male location and social status, potentially biasing estimated patterns of paternity. studies that achieve comprehensive sampling and paternity assignment are therefore requir ...	2010	20819155
aggressive interactions rapidly increase androgen synthesis in the brain during the non-breeding season.	in male song sparrows (melospiza melodia), territorial challenges during the breeding season can rapidly increase circulating levels of testosterone (t). during the non-breeding season, male song sparrows are highly aggressive, but the gonads are regressed and plasma t levels are non-detectable and unaffected by territorial challenges. the pro-hormone dehydroepiandrosterone (dhea) is elevated in song sparrow plasma and brain during the non-breeding season and may be locally converted to sex ster ...	2010	20116379
population differences in fever and sickness behaviors in a wild passerine: a role for cytokines.	immune responses benefit hosts by clearing pathogens, but they also incur physiological costs and tissue damage. while wild animals differ in how they balance these costs and benefits, the physiological mechanisms underlying such differential investment in immunity remain unknown. uncovering these mechanisms is crucial to determining how and where selection acts to shape immunological defense. among free-living song sparrows (melospiza melodia) in western north america, sickness-induced lethargy ...	2010	21075952
heritability of female extra-pair paternity rate in song sparrows (melospiza melodia).	the forces driving the evolution of extra-pair reproduction in socially monogamous animals remain widely debated and unresolved. one key hypothesis is that female extra-pair reproduction evolves through indirect genetic benefits, reflecting increased additive genetic value of extra-pair offspring. such evolution requires that a female's propensity to produce offspring that are sired by an extra-pair male is heritable. however, additive genetic variance and heritability in female extra-pair pater ...	2011	20980302
perceived predation risk reduces the number of offspring songbirds produce per year.	predator effects on prey demography have traditionally been ascribed solely to direct killing in studies of population ecology and wildlife management. predators also affect the prey's perception of predation risk, but this has not been thought to meaningfully affect prey demography. we isolated the effects of perceived predation risk in a free-living population of song sparrows by actively eliminating direct predation and used playbacks of predator calls and sounds to manipulate perceived risk. ...	2011	22158817
radiation exposure differentially affects songbird 8-hydroxy-2'-deoxyguanosine plasma profiles: ionizing radiation damage response in songbirds.	the importance of understanding the effects of radiation exposure on wildlife is a critical responsibility of our stewardship of nuclear energy production. we tested the hypothesis that songbirds respond to exogenous radiation exposure with changes in plasma 8-hydroxy-2'-deoxyguanosine (8-oh-dg). we exposed two species of songbirds, house sparrows (passer domesticus; n = 12) and song sparrows (melospiza melodia; n = 12), to one of four acute whole-body radiation treatments: 75, 150, 300, or 600 ...	2011	21809389
aggressive interactions differentially modulate local and systemic levels of corticosterone and dhea in a wild songbird.	during the nonbreeding season, when gonadal androgen synthesis is basal, recent evidence suggests that neurosteroids regulate the aggression of male song sparrows. in particular, dehydroepiandrosterone (dhea) is rapidly converted in the brain to androgens in response to aggressive interactions. in other species, aggressive encounters increase systemic glucocorticoid levels. however, the relationship between aggression and local steroid levels is not well understood. here, during the breeding and ...	2011	21784076
additive genetic variance, heritability, and inbreeding depression in male extra-pair reproductive success.	the hypothesis that female extra-pair reproduction in socially monogamous animals reflects indirect genetic benefits requires that there be additive and/or nonadditive genetic variance in fitness. however, the specific hypotheses that male extra-pair reproductive success (eprs) shows additive genetic variance (v(a)), heritability (h2), or inbreeding depression, and hence that females could acquire indirect genetic benefits through increased eprs of sons, have not been explicitly tested. we used ...	2011	21460554
sex-specific differential survival of extra-pair and within-pair offspring in song sparrows, melospiza melodia.	it is widely hypothesized that the evolution of female extra-pair reproduction in socially monogamous species reflects indirect genetic benefits to females. however, a critical prediction of this hypothesis, that extra-pair young (epy) are fitter than within-pair young (wpy), has rarely been rigorously tested. we used 18 years of data from free-living song sparrows, melospiza melodia, to test whether survival through major life-history stages differed between epy and wpy maternal half-siblings. ...	2011	21389032
disentangling the effect of genes, the environment and chance on sex ratio variation in a wild bird population.	sex ratio theory proposes that the equal sex ratio typically observed in birds and mammals is the result of natural selection. however, in species with chromosomal sex determination, the same 1 : 1 sex ratio is expected under random mendelian segregation. here, we present an analysis of 14 years of sex ratio data for a population of song sparrows (melospiza melodia) on mandarte island, at the nestling stage and at independence from parental care. we test for the presence of variance in sex ratio ...	2011	21345862
multiple measures elucidate glucocorticoid responses to environmental variation in predation threat.	predator-induced changes in the glucocorticoid responses of prey have been proposed to mediate indirect predator effects on prey demography. ambiguities exist, however, as to whether differences in predation threat in the environment at large affect the mean glucocorticoid response in wild birds and mammals, and whether this is likely to affect reproduction. most studies to date that have examined glucocorticoid responses to environmental variation in predation threat have evaluated just one of ...	2011	21279653
lead exposure and poisoning of songbirds using the coeur d'alene river basin, idaho.	previous studies have found widespread pb poisoning of waterfowl in the coeur d'alene river basin in northern idaho, usa, which has been contaminated by mining and smelting activities. we studied the exposure of ground-feeding songbirds to pb, sampling 204 american robins (turdus migratorius), song sparrows (melospiza melodia), and swainson's thrushes (catharus ustulatus) throughout the basin. these songbirds had mean blood pb concentrations (mg/kg, dry weight) of less than 0.19 at a reference a ...	2011	21538831
assessment of risks to ground-feeding songbirds from lead in the coeur d'alene basin, idaho.	previous assessment of ecological risks within the coeur d'alene basin identified lead as a key risk driver for ground-feeding songbirds. as this conclusion was based almost exclusively on literature data, its strength was determined to range from low to moderate. with the support of the u.s. environmental protection agency (usepa), the u.s. fish and wildlife service collected site-specific data to address the uncertainty associated with lead risks to songbirds. these data, plus those from the p ...	2011	21793201
Widespread dispersal of Borrelia burgdorferi-infected ticks collected from songbirds across Canada.	Abstract Millions of Lyme disease vector ticks are dispersed annually by songbirds across Canada, but often overlooked as the source of infection. For clarity on vector distribution, we sampled 481 ticks (12 species and 3 undetermined ticks) from 211 songbirds (42 species/subspecies) nationwide. Using PCR, 52 (29.5%) of 176 Ixodes ticks tested were positive for the Lyme disease spirochete, Borrelia burgdorferi s.l. Immature blacklegged ticks, Ixodes scapularis, collected from infested songbird ...	2011	21864130
songbird response to increased willow (salix spp.) growth in yellowstone's northern range.	after nearly a century of height suppression, willows (salix spp.) in the northern range of yellowstone national park, u.s.a., are increasing in height growth as a possible consequence of wolf (canis lupus) restoration, climate change, or other factors. regardless of the drivers, the recent release of this rare but important habitat type could have significant implications for associated songbirds that are exhibiting declines in the region. our objective was to evaluate bird response to releasin ...	2011	21939061
zenk expression in auditory regions changes with breeding condition in male black-capped chickadees (poecile atricapillus).	black-capped chickadees (poecile atricapillus) produce different vocalizations at different times of year: the fee-bee song is produced by males primarily in spring, whereas the chick-a-dee call is produced year-round but most frequently in the fall and winter. we wanted to determine if neural response to playback in auditory regions of the songbird brain varied with season in parallel to production. we captured adult male black-capped chickadees from the wild in either breeding condition or non ...	2011	21854811
the zebra finch paradox: song is little changed, but number of neurons doubles.	new neurons are added to the high vocal center (hvc) of adult males in seasonally breeding songbirds such as the canary (serinus canaria) that learns new songs in adulthood, and the song sparrow (melospiza melodia) that does not. in both cases, the new neurons numerically replace others that have died, resulting in a seasonal fluctuation in hvc volume and neuron number. peaks in neuronal replacement in both species occur in the fall when breeding is over and song is variable. new neurons are add ...	2012	22262875
transcriptome analysis of a north american songbird, melospiza melodia.	an effective way to understand the genomics of divergence in non-model organisms is to use the transcriptome to identify genes associated with divergence. we examine the transcriptome of the song sparrow (melospiza melodia) and contrast it with the avian models zebra finch (taeniopygia guttata) and chicken (gallus gallus). we aimed to (i) obtain a functional annotation of a substantial portion of the song sparrow transcriptome; (ii) compare transcript divergence; (iii) efficiently characterize s ...	2012	22645122
indirect selection on female extra-pair reproduction? comparing the additive genetic value of maternal half-sib extra-pair and within-pair offspring.	one specific hypothesis explaining the evolution of extra-pair reproduction (epr) by socially monogamous females is that epr is under indirect selection because extra-pair offspring (epo) sired by extra-pair males have higher additive genetic value for fitness than the within-pair offspring (wpo) a female would have produced had she solely mated with her socially paired male. this hypothesis has not been explicitly tested by comparing additive genetic value between epo and the wpo they replaced. ...	2012	22113036
to flock or fight: neurochemical signatures of divergent life histories in sparrows.	many bird species exhibit dramatic seasonal switches between territoriality and flocking, but whereas neuroendocrine mechanisms of territorial aggression have been extensively studied, those of seasonal flocking are unknown. we collected brains in spring and winter from male field sparrows (spizella pusilla), which seasonally flock, and male song sparrows (melospiza melodia), which are territorial year-round in much of their range. spring collections were preceded by field-based assessments of a ...	2012	22723363
the influence of the california marine layer on bill size in a generalist songbird.	the hypothesis is tested that birds in hotter and drier environments may have larger bills to increase the surface area for heat dissipation. california provides a climatic gradient to test the influence of climate on bill size. much of california experiences dry warm/hot summers and coastal areas experience cooler summers than interior localities. based on measurements from 1488 museum skins, song sparrows showed increasing body-size-corrected bill surface area from the coast to the interior an ...	2012	23206140
extra-pair paternity and the variance in male fitness in song sparrows (melospiza melodia).	the variance in fitness across population members can influence major evolutionary processes. in socially monogamous but genetically polygynandrous species, extra-pair paternity (epp) is widely hypothesized to increase the variance in male fitness compared to that arising given the socially monogamous mating system. this hypothesis has not been definitively tested because comprehensive data describing males' apparent (social) and realized (genetic) fitness have been lacking. we used 16 years of ...	2012	23025602
predicting evolutionary responses to selection on polyandry in the wild: additive genetic covariances with female extra-pair reproduction.	the evolutionary forces that underlie polyandry, including extra-pair reproduction (epr) by socially monogamous females, remain unclear. selection on epr and resulting evolution have rarely been explicitly estimated or predicted in wild populations, and evolutionary predictions are vulnerable to bias due to environmental covariances and correlated selection through unmeasured traits. however, evolutionary responses to (correlated) selection on any trait can be directly predicted as additive gene ...	2012	22993252
soft song during aggressive interactions: seasonal changes and endocrine correlates in song sparrows.	it is well known that songbirds produce high amplitude songs ("broadcast songs"). songbirds also produce low amplitude songs ("soft songs") during courtship or territorial aggression in the breeding season. soft songs are important social signals but have been studied far less than broadcast songs. to date, no studies have examined seasonal changes in soft song or its endocrine regulation. here, in male song sparrows, we examined soft songs during a simulated territorial intrusion in the breedin ...	2012	22902893
offspring fitness varies with parental extra-pair status in song sparrows, melospiza melodia.	numerous studies have tested for indirect selection on female extra-pair reproduction (epr) by quantifying whether extra-pair young (epy) are fitter than their within-pair young (wpy) maternal half-siblings. in contrast, the hypothesis that offspring of epy and wpy (rather than the epy and wpy themselves) differ in fitness has not been tested, even though inter-generational effects of parental extra-pair status on offspring fitness could alter the magnitude and direction of indirect selection on ...	2012	22874751
heat loss may explain bill size differences between birds occupying different habitats.	research on variation in bill morphology has focused on the role of diet. bills have other functions, however, including a role in heat and water balance. the role of the bill in heat loss may be particularly important in birds where water is limiting. song sparrows localized in coastal dunes and salt marsh edge (melospiza melodia atlantica) are similar in size to, but have bills with a 17% greater surface area than, those that live in mesic habitats (m. m. melodia), a pattern shared with other ...	2012	22848413
the presence of water influences reproductive function in the song sparrow (melospiza melodia morphna).	cumulative evidence indicates that song sparrows, melospiza melodia morphna, of western washington state prefer territories close to water. densities of territories were higher within 50 m of open water and analysis of stomach contents revealed aquatic organisms. an unusually dry period (less open water) in may and june 1997 had no effect on latency of territorial males to respond to a simulated territorial intrusion (sti), but the number of songs and closest approach to the decoy were lower tha ...	2012	22809668
developmental stress has sex-specific effects on nestling growth and adult metabolic rates but no effect on adult body size or body composition in song sparrows.	variation in the prenatal and postnatal environments can have long-term effects on adult phenotype. in humans and other animals, exposure to stressors can lead to long-term changes in physiology. these changes may predispose individuals to disease, especially disorders involving energy metabolism. in addition, by permanently altering metabolic rates and energy requirements, such effects could have important fitness consequences. we determined the effects of early-life food restriction and cortic ...	2012	22693025
are there indirect fitness benefits of female extra-pair reproduction? lifetime reproductive success of within-pair and extra-pair offspring.	the forces driving extra-pair reproduction by socially monogamous females, and the resulting genetic polyandry, remain unclear. a testable prediction of the hypothesis that extra-pair reproduction partly reflects indirect selection on females is that extra-pair young (epy) will be fitter than their within-pair young (wpy) maternal half-siblings. this prediction has not been comprehensively tested in a wild population, requiring data on the lifetime reproductive success (lrs) of maternal half-sib ...	2012	22617265
spatial movements and social networks in juvenile male song sparrows.	the time between fledging and breeding is a critical period in songbird ontogeny, but the behavior of young songbirds in the wild is relatively unstudied. the types of social relationships juveniles form with other individuals can provide insight into the process through which they learn complex behaviors crucial for survival, territory establishment, and mate attraction. we used radio telemetry to observe social associations of young male song sparrows (melospiza melodia) from may to november. ...	2012	22479140
regulation of the hpa axis is related to song complexity and measures of phenotypic quality in song sparrows.	regulation of the hypothalamic-pituitary-adrenal (hpa) axis is a key component of the vertebrate stress response. prior studies have found that variation in hpa responses were correlated to measures of fitness and physiological condition. in addition, sexually-selected traits have also been found to correlate to measures of condition. the proximate mechanisms responsible for such covariation between sexually selected traits and measures of quality are unclear, but could involve variation in hpa ...	2012	22418051
immediate and long-term effects of testosterone on song plasticity and learning in juvenile song sparrows.	steroid sex hormones play critical roles in the development of brain regions used for vocal learning. it has been suggested that puberty-induced increases in circulating testosterone (t) levels crystallize a bird's repertoire and inhibit future song learning. previous studies show that early administration of t crystallizes song repertoires but have not addressed whether new songs can be learned after this premature crystallization. we brought 8 juvenile song sparrows (melospiza melodia) into th ...	2012	22387677
rapid and widespread effects of 17β-estradiol on intracellular signaling in the male songbird brain: a seasonal comparison.	across vertebrate species, 17β-estradiol (e(2)) acts on the brain via both genomic and nongenomic mechanisms to influence neuronal physiology and behavior. nongenomic e(2) signaling is typically initiated by membrane-associated estrogen receptors that modulate intracellular signaling cascades, including rapid phosphorylation of erk. phosphorylated erk (perk) can, in turn, rapidly phosphorylate tyrosine hydroxylase (th) and camp response element-binding protein (creb). recent data suggest that th ...	2012	22294743
self-regulated learning of a natural category: do people interleave or block exemplars during study?	despite decades of research focused on the representation of concepts, little is known about the influence of self-regulatory processes when learning natural categories. such work is vital, as many contexts require self-regulation when we form complex concepts. previous research has demonstrated that interleaving, as compared to blocking, can improve classification. thus, as an initial step to explore self-regulated learning of natural concepts, we evaluated whether people chose to block or inte ...	2013	23055143
the effect of polychlorinated biphenyls on the song of two passerine species.	polychlorinated biphenyls (pcbs) are synthetic chemical pollutants with demonstrated detrimental toxic and developmental effects on humans and wildlife. laboratory studies suggest that pcbs influence behavior due to their effects on endocrine and neurological systems, yet little is known about the behavioral consequences of sublethal pcb exposure in the field. additionally, specific pcb congener data (in contrast to total pcb load) is necessary to understand the possible effects of pcbs in livin ...	2013	24058475
projected hg dietary exposure of 3 bird species nesting on a contaminated floodplain (south river, virginia, usa).	dietary hg exposure was modeled for carolina wren (thryothorus ludovicianus), eastern song sparrow (melospiza melodia), and eastern screech owl (otus asio) nesting on the contaminated south river floodplain (virginia, usa). parameterization of monte-carlo models required formal expert elicitation to define bird body weight and feeding ecology characteristics because specific information was either unavailable in the published literature or too difficult to collect reliably by field survey. mercu ...	2013	22987580
dependent vs. independent juvenile survival: contrasting drivers of variation and the buffering effect of parental care.	juvenile survival is often found to be more sensitive than adult survival to variation in environmental conditions, and variation in juvenile survival can have significant impacts on population growth rates and viability. therefore, understanding the population-level effects of environmental changes requires understanding the effects on juvenile survival. we hypothesized that parental care will buffer the survival of dependent juveniles from variation in environmental conditions, while the survi ...	2013	23951718
hpa axis regulation, survival, and reproduction in free-living sparrows: functional relationships or developmental correlations?	a growing body of theoretical and empirical work has addressed the relationship between hypothalamus-pituitary-adrenal (hpa) function and fitness. for example, the corticosterone (cort)-fitness and cort-condition hypotheses predict that baseline and/or stress-induced levels of glucocorticoids should relate to fitness, and recent empirical studies have reported relationships between hpa function and fitness-related sexually selected traits. here we introduce a framework for evaluating whether suc ...	2013	23770216
nongenomic effects of estradiol on aggression under short day photoperiods.	in several vertebrate species, the effects of estrogens on male aggressive behavior can be modulated by environmental cues. in song sparrows and rodents, estrogens modulate aggression in the nonbreeding season or winter-like short days, respectively. the behavioral effects of estrogens are rapid, which generally is considered indicative of nongenomic processes. the current study further examined the hypothesis that estradiol acts nongenomically under short days by utilizing a protein synthesis i ...	2013	23763907
potential trade-off between vocal ornamentation and spatial ability in a songbird.	bird song is hypothesized to be a reliable indicator of cognition because it depends on brain structure and function. song features have been found to correlate positively with measures of cognition, but the relationship between song and cognition is complicated because not all cognitive abilities are themselves positively correlated. if cognition is not a unitary trait, developmental constraints on brain growth could generate trade-offs between some aspects of cognition and song. to further cla ...	2013	23697642
climate, ecological release and bill dimorphism in an island songbird.	sexual size dimorphism is expected to be more pronounced in vertebrates on islands, particularly in trophic characters, as a response to decreased interspecific competition for food. we found (based on measurements of 1423 museum specimens) that bill size dimorphism was greater in island than mainland populations of song sparrows. however, dimorphism varied among islands and was positively correlated with high summer temperature and island size. island song sparrow bills follow the overall posit ...	2013	23616645
projecting demographic responses to climate change: adult and juvenile survival respond differently to direct and indirect effects of weather in a passerine population.	few studies have quantitatively projected changes in demography in response to climate change, yet doing so can provide important insights into the processes that may lead to population declines and changes in species distributions. using a long-term mark-recapture data set, we examined the influence of multiple direct and indirect effects of weather on adult and juvenile survival for a population of song sparrows (melospiza melodia) in california. we found evidence for a positive, direct effect ...	2013	23606580
decomposing variation in male reproductive success: age-specific variances and covariances through extra-pair and within-pair reproduction.	age-specific variances and covariances in reproductive success shape the total variance in lifetime reproductive success (lrs), age-specific opportunities for selection, and population demographic variance and effective size. age-specific (co)variances in reproductive success achieved through different reproductive routes must therefore be quantified to predict population, phenotypic and evolutionary dynamics in age-structured populations. while numerous studies have quantified age-specific vari ...	2013	23470041
song type matching is an honest early threat signal in a hierarchical animal communication system.	aggressive encounters between animals often involve significant amounts of signalling before or in lieu of physical fights. when, as is often the case, these apparent threat signals are neither inherently costly nor inherently indicative of fighting ability, we should ask whether they are in fact honest signals, i.e. do they predict that escalation is imminent? while signalling theories have indicated that such 'conventional' threat signals can honestly predict escalation, attempts to gather sup ...	2013	23378665
food use is affected by the experience of nest predation: implications for indirect predator effects on clutch size.	indirect predator effects on prey demography include any effect not attributable to direct killing and can be mediated by perceived predation risk. though perceived predation risk clearly affects foraging, few studies have yet demonstrated that it can chronically alter food intake to an extent that affects demography. recent studies have used stable isotopes to gauge such chronic effects. we previously reported an indirect predator effect on the size of subsequent clutches laid by song sparrows ...	2013	23292453
effects of corticosterone on territorial behavior of free-living male song sparrows melospiza melodia.	a group of 10 territorial male song sparrows, melospiza melodia, were given subcutaneous implants of corticosterone in silastic tubing. a second group of 10 territorial males were given empty implants as controls. after 18-24 hr all males were then subjected to a simulated territorial intrusion (sti) by placing a caged male song sparrow in the center of the subject's territory, and playing tape recorded songs through a speaker placed alongside. significantly fewer males with corticosterone impla ...	2013	3793022
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
developmental stress, condition, and birdsong: a case study in song sparrows.	sexual-selection theory posits that ornaments and displays can reflect a signaler's condition, which in turn is affected both by recent and developmental conditions. moreover, developmental conditions can induce correlations between sexually selected and other traits if both types of traits exhibit developmental phenotypic plasticity in response to stressors. thus, sexually selected traits may reflect recent and/or developmental characteristics of signalers. here, we review data on the relations ...	2014	24951504
brain transcriptome sequencing and assembly of three songbird model systems for the study of social behavior.	emberizid sparrows (emberizidae) have played a prominent role in the study of avian vocal communication and social behavior. we present here brain transcriptomes for three emberizid model systems, song sparrow melospiza melodia, white-throated sparrow zonotrichia albicollis, and gambel's white-crowned sparrow zonotrichia leucophrys gambelii. each of the assemblies covered fully or in part, over 89% of the previously annotated protein coding genes in the zebra finch taeniopygia guttata, with 16,8 ...	2014	24883256
developmental timing of signals affects information content: song complexity but not consistency reflects innate immune strategy in male song sparrows.	in short-lived animals, innate immunity is an important component of fitness and quality. although receivers cannot generally assess a signaler's immune function directly, sexually selected displays such as birdsong may reflect past or current condition. we investigated the degree to which song complexity and consistency, thought to reflect condition over different developmental timescales, predict multiple aspects of innate immunity in male song sparrows (melospiza melodia). we also investigate ...	2014	24739198