Publications

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hearing in passerine and psittacine birds: a comparative study of absolute and masked auditory thresholds.operant conditioning and a psychophysical tracking procedure were used to measure auditory thresholds for pure tones in quiet and in noise for seven species of small birds--the budgerigar, canary, cockatiel, european starling, song sparrow, swamp sparrow, and the zebra finch. audibility curves are roughly similar among the seven birds, with the maximum sensitivity between 2 and 5 khz and poorer sensitivity outside this narrow region. critical ratios (signal-to-noise ratio at masked threshold) we ...19873568610
temporal spacing of broods, brood size, and parental care in song sparrows (melospiza melodia). 19807427795
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 ...200415605649
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 ...200515962798
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 ...201020653028
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 ...201020618658
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 ...201121864130
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 ...200818252675
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 ...200717427704
use of observed wild bird activity on poultry farms and a literature review to target species as high priority for avian influenza testing in 2 regions of canada.the risk of avian influenza outbreaks in poultry is partially dependent on the probability of contact between domestic poultry and wild birds shedding avian influenza (ai) virus. the major objective of this study was to document wild bird activity on poultry farms to determine which wild bird species should be targeted for ai surveillance in canada. we collected data in 2 major poultry producing regions of canada, southwestern ontario and the fraser valley of british columbia, on the relative ab ...022851777
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 ...200717427703
acetylcholinesterase in central vocal control nuclei of the zebra finch (taeniopygia guttata).the distribution of acetylcholinesterase (ache) in the central vocal control nuclei of the zebra finch was studied using enzyme histochemistry. ache fibres and cells are intensely labelled in the forebrain nucleus area x, strongly labelled in high vocal centre (hvc) perikarya, and moderately to lightly labelled in the somata and neuropil of vocal control nuclei robust nucleus of arcopallium (ra), medial magnocellular nucleus of the anterior nidopallium (mman) and lateral magnocellular nucleus of ...200415286416
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 ...200617172382
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 ...200617148291
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 ...200717374595
gonadotropin-inhibitory hormone in gambel's white-crowned sparrow (zonotrichia leucophrys gambelii): cdna identification, transcript localization and functional effects in laboratory and field experiments.the neuropeptide control of gonadotropin secretion is primarily through the stimulatory action of the hypothalamic decapeptide, gnrh. we recently identified a novel hypothalamic dodecapeptide with a c-terminal leupro-leu-arg-phe-nh2 sequence in the domestic bird, japanese quail (coturnix japonica). this novel peptide inhibited gonadotropin release in vitro from the quail anterior pituitary; thus it was named gonadotropin-inhibitory hormone (gnih). gnih may be an important factor regulating repro ...200415225129
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 ...200919473242
experimental infection of california birds with western equine encephalomyelitis and st. louis encephalitis viruses.a total of 27 bird species from the san joaquin and coachella valleys of california were inoculated subcutaneously with sympatric strains of western equine encephalomyelitis (wee) and st. louis encephalitis (sle) viruses. overall, 133 of 164 birds inoculated with wee virus developed a viremia detected by plaque assay; significantly greater than 72 of 163 birds inoculated with sle virus. host competence was calculated as the average number of days that each avian species had a viremia > or = 2 lo ...200314765678
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 ...201020646123
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 ...200516096849
discrimination between host songs by brood parasitic brown-headed cowbirds ( molothrus ater).songbirds can learn both to produce and to discriminate between different classes of acoustic stimuli. varying levels of auditory discrimination may improve the fitness of individuals in certain ecological and social contexts and, thus, selection is expected to mold the cognitive abilities of different species according to the potential benefits of acoustic processing. although fine-scale auditory discrimination of conspecific songs and calls has been frequently reported for brood parasitic brow ...200212357285
foxp2 expression in avian vocal learners and non-learners.most vertebrates communicate acoustically, but few, among them humans, dolphins and whales, bats, and three orders of birds, learn this trait. foxp2 is the first gene linked to human speech and has been the target of positive selection during recent primate evolution. to test whether the expression pattern of foxp2 is consistent with a role in learned vocal communication, we cloned zebra finch foxp2 and its close relative foxp1 and compared mrna and protein distribution in developing and adult b ...200415056696
birds disperse ixodid (acari: ixodidae) and borrelia burgdorferi-infected ticks in canada.a total of 152 ixodid ticks (acari: ixodidae) consisting of nine species was collected from 82 passerine birds (33 species) in 14 locations in canada from 1996 to 2000. the lyme disease spirochete borrelia burgdorferi johnson, schmidt, hyde, steigerwaldt & brenner was cultured from the nymph of a blacklegged tick, ixodes scapularis say, that had been removed from a common yellowthroat, geothlypis trichas l., from bon portage island, nova scotia. as a result of bird movement, a nymphal i. scapula ...200111476328
lesions of the anterior forebrain song control pathway in female canaries affect song perception in an operant task.we tested whether the avian anterior forebrain pathway functions in song perception in female canaries, and whether it is specialized for conspecific song perception or functions more generally in auditory perception. using operant conditioning methods, we trained female canaries to discriminate among synthetic sound stimuli, canary songs, and song sparrow songs. we also trained each bird to discriminate among visual stimuli to test for general effects of lesions on performance. when canaries ha ...200010623896
gonadotropin-inhibitory peptide in song sparrows (melospiza melodia) in different reproductive conditions, and in house sparrows (passer domesticus) relative to chicken-gonadotropin-releasing hormone.gonadotropin-releasing hormone (gnrh) regulates reproduction in all vertebrates. until recently, an antagonistic neuropeptide for gonadotropin was unknown. the discovery of an rfamide peptide in quail that inhibits gonadotropin release in vitro raised the possibility of direct hypothalamic inhibition of gonadotropin release. this peptide has now been named gonadotropin-inhibitory hormone (gnih). we investigated gnih presence in the hypothalamus of two seasonally breeding songbird species, house ...200312834441
isolation and characterization of borrelia burgdorferi from blood of a bird captured in the saint croix river valley.field investigations were conducted to further evaluate the role of birds in the maintenance and dissemination of borrelia burgdorferi. blood specimens were taken from 39 passerine birds of 17 species captured during june 1991 at the saint croix national riverway in wisconsin, and one isolate, wi91-23, was cultured from an adult song sparrow (melospiza melodia). this isolate was shown to be infectious for peromyscus leucopus and mesocricetus auratus (golden hamster). isolate wi91-23 was confirme ...19938370728
environmental and endocrine control of reproduction in the song sparrow, melospiza melodia. i. temporal organization of the breeding cycle.endocrinologic investigations of free-living populations of song sparrows, melospiza melodia, have revealed temporal patterns of secretion of reproductive hormones that differ from those of other monogamous avian species. males arrive in the breeding area in march whereas females arrive 1-2 weeks later. in males the periods of territory establishment and attraction of a mate are characterized by high circulating levels of luteinizing hormone (lh) and testosterone (t), whereas testis mass is low, ...19846510698
heavy metals and metalloids in egg contents and eggshells of passerine birds from arizona.concentrations of inorganic elements were determined in eggs of passerine birds including the endangered southwestern willow flycatcher (empidonax traillii extimus) from four regions in arizona. the main aim of the study was to determine the distribution of metals in egg contents and eggshells, with emphasis on the deposition of sr in eggshells. seventy eggs of 11 passerine species were collected at four nesting locations during 2000. aluminum, ba, cr, cu, mn, se, sr, and zn, were detected prima ...200312826417
immunohistochemical localization of neuropeptides in the vocal control regions of two songbird species.immunohistochemistry was used to map the distribution of four neuropeptides in song control regions of two songbird species, the european starling (sturnus vulgaris) and the song sparrow (melospiza melodia). we searched for positively stained cell bodies or apparent terminals containing vasoactive intestinal peptide (vip), methionine-enkephalin (met), cholecystokinin (cck), and substance p (sub p). intraventricular colchicine pretreatment was administered to enhance the visualization of peptide- ...19882452178
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 ...201020653036
bird song learning as an adaptive strategy.parallels are often drawn between bird song learning and human language learning. the analogies include an early sensitive period for learning, separation of sensory and motor phases of learning, 'innate knowledge' of language or song, and specialized neural systems. nevertheless, in distinction to human language learning, song learning is usually viewed as a purely auditory process. this view is implied in the typical experimental paradigm for studying song learning, in which the bird is isolat ...19979386917
identity of gonadotropin-releasing hormone in passerine birds: comparison of gnrh in song sparrow (melospiza melodia) and starling (sturnus vulgaris) with five vertebrate gnrhs.gonadotropin-releasing hormone (gnrh) was detected in the brains of passerine birds, a recently evolved and diverse avian group. the molecular forms of gnrh in two species of birds under breeding conditions were deduced using methods of hplc and immunology. the brain extracts of song sparrows (melospiza melodia) contained a form of gnrh identified as chicken i gnrh-like peptide by its hplc elution pattern and cross-reactivity with four antisera. in contrast, starling (sturnus vulgaris) brain ext ...19883282980
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 ...201222262875
hamilton and zuk meet heterozygosity? song repertoire size indicates inbreeding and immunity in song sparrows (melospiza melodia).hamilton and zuk's influential hypothesis of parasite-mediated sexual selection proposes that exaggerated secondary sexual ornaments indicate a male's addictive genetic immunity to parasites. however, genetic correlated of ornaments and immunity have rarely been explicitly identified. evidence supporting hamilton and zuk's hypothesis has instead been gathered by looking for positive phenotypic correlations between ornamentation and immunity; such correlations are assumed to reflect causal, addic ...015799943
effects of insecticide use on breeding birds in christmas tree plantations in quebec.: this research, which was carried out in the spring of 1989 and 1990 in seven balsam fir (abies balsamea) plantations in southeastern quebec, examines potential deleterious effects of three insecticides (i.e. dimethoate, diazinon and insecticidal soap) on breeding american robins (turdus migratorius) (n=87 nests) and song sparrows (melospizsa melodia) (n=41 nests). through analyses of blood serum cholinesterases (ache and bche) activity both prior to and the second day following applications of ...199524197796
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 ...201525730273
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 ...201628030559
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 ...201121538831
nest predation by cowbirds and its consequences for passerine demography.brood parasitism by brown-headed cowbirds (molothrus ater) reduces reproductive success in many passerines that nest in fragmented habitats and ecological edges, where nest predation is also common. we tested the hypothesis that parasitism and predation are often linked because cowbirds depredate nests discovered late in the host's nesting cycle to enhance future opportunities for parasitism. over a 20-year study period, brood parasitism by cowbirds was a prerequisite to observing marked inter- ...199611607677
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 ...20133793022
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 ...201121793201
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 ...201627330174
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 ...201627853596
selection against inbred song sparrows during a natural population bottleneck.the genetic and demographic consequences of population subdivision have received considerable attention from conservation biologists. in particular, losses of genetic variability and reduced viability and fecundity due to inbreeding (inbreeding depression) are of concern. studies of domestic, laboratory and zoo populations have shown inbreeding depression in a variety of traits related to fitness. consequently, inbreeding depression is widely accepted as a fact. recently, however, the relative i ...19947969492
song sparrows, top carnivores and nest predation: a test of the mesopredator release hypothesis.ground-nesting north american landbirds have declined in the longterm, including species with a variety of migratory strategies. the mesopredator release hypothesis explains declines by suggesting that the virtual elimination of top carnivores (large-bodied canids and felids) from much of north america has "released" populations of nest-destroying mesopredators (i.e., medium-sized terrestrial omnivores such as the raccoon procyon lotor). the hypothesis predicts (1) higher nest success in the pre ...199828308530
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 ...201728250184
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 ...201727940472
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 ...201121854811
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 ...201121939061
muscarinic cholinergic receptors in the songbird and quail brain: a quantitative autoradiographic study.in order to clarify the neuroanatomical basis for postulated muscarinic cholinergic control of a wide array of physiological processes in birds, the distribution of muscarinic cholinergic receptors in the brain of three avian species was investigated by quantitative autoradiography. the species consisted of two passerines (songbirds), the european starling (sturnus vulgaris) and the song sparrow (melospiza melodia), and one galliform, the japanese quail (coturnix coturnix japonica). [3h]n-methyl ...19902229474
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 ...201728387020
comparative phylogeography in north american birds.modern molecular methods yield descriptions of the phylogenetic deployment of genetic variation within species, or phylogeography. a developing field is the comparison of geographic patterns of genetic variation in codistributed species, or comparative phylogeography. one determines whether species that currently share the same broad area exhibit congruent phylogeographic patterns, which would indicate that they were historically codistributed and differentiated in response to same geological or ...199628568862
natural selection on beak and body size in the song sparrow.we documented temporal patterns of natural selection on beak and body traits in a song sparrow population. we looked for evidence of selection in association with reproduction and overwinter survival in order to identify the conditions under which size in beak and body traits is adaptive. we also attempted to identify the specific traits most closely associated with fitness under these conditions. selection was observed in association with both survival and reproduction. patterns of selection di ...198628556039
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 ...201728869682
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 ...201728757672
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 ...201728434901
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 ...201728403152
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 ...201627805753
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 ...201627448623
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 ...201627534598
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 ...201627174154
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 ...201627172593
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 ...201727844219
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 ...201626648568
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 ...201526573880
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 ...201526420476
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 ...201526308717
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") ...201525980562
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 ...201525976301
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 ...201627807264
correction to 'agonistic urban birds: elevated territorial aggression of urban song sparrows is individually consistent within a breeding period'. 201627903781
song structure without auditory feedback: emendations of the auditory template hypothesis.motor patterns of songs of swamp and song sparrows, melospiza georgiana and m. melodia, deafened early in life display a significant degree of species-specific structure. normal songs of the two species differ in the degree to which they are segmented. swamp sparrow song consists of a single segment, and song sparrow songs are multisegmental. song and swamp sparrows were deafened at 17 to 23 days, prior to the onset of song or subsong. the song sparrows developed more segments in their singing t ...19836827307
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 ...201525346331
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 ...201323763907
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 ...201525645743
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 ...201323616645
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 ...201525483754
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 ...200919725863
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 ...201222645122
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 ...201323697642
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 ...201425234377
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 ...201425186454
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 ...201424951504
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 ...201222993252
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 ...201424883256
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 ...201424739198
the distribution and extent of heavy metal accumulation in song sparrows along arizona's upper santa cruz river.heavy metals are persistent environmental contaminants, and transport of metals into the environment poses a threat to ecosystems, as plants and wildlife are susceptible to long-term exposure, bioaccumulation, and potential toxicity. we investigated the distribution and cascading extent of heavy metal accumulation in southwestern song sparrows (melospiza melodia fallax), a resident riparian bird species that occurs along the us/mexico border in arizona's upper santa cruz river watershed. this st ...201424729180
female and male genetic effects on offspring paternity: additive genetic (co)variances in female extra-pair reproduction and male paternity success in song sparrows (melospiza melodia).ongoing evolution of polyandry, and consequent extra-pair reproduction in socially monogamous systems, is hypothesized to be facilitated by indirect selection stemming from cross-sex genetic covariances with components of male fitness. specifically, polyandry is hypothesized to create positive genetic covariance with male paternity success due to inevitable assortative reproduction, driving ongoing coevolution. however, it remains unclear whether such covariances could or do emerge within comple ...201424724612
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 ...201424685383
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 ...201424669736
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 ...201424650781
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 ...201424307671
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 ...201424291303
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 ...201424171712
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. ...201424123830
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 ...201324058475
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 ...201525865627
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 ...201525678475
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 ...201323606580
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 ...201424048882
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