Publications

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 ...	0	22851777
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 ...	0	15799943
variation in blood group frequencies in populations of song sparrows of the san francisco bay region.		1966	28562979
competitive release in island song sparrow populations.		1974	4818407
selective vocal learning in a sparrow.	male swamp sparrows learn their songs; they fail to learn songs of the sympatric song sparrow. syllables from tape recordings of both species of sparrow were spliced into an array of swamp sparrow-like and song sparrow-like temporal patterns. swamp sparrows learned only those songs made of swamp sparrow syllables. they did so irrespective of whether the temporal pattern was swamp sparrow-like or song sparrow-like. selectivity was retained by birds reared in total isolation from adult conspecific ...	1977	17842140
a re-evaluation of song development in the song sparrow.	song sparrows were hand-reared from the egg in auditory isolation from adult conspecifics and maintained either together with other species or individually in sound chambers. songs developed by the males contained several normal species-specific characteristics, but on the whole differed both qualitatively and quantitatively and were therefore readily distinguished from wild-type songs. the data are largely consistent with those of mulligan (1966), but the normal aspects of song development have ...	1977	889151
heritability of some morphological characters in a song sparrow population.		1979	28568196
experimental confirmation of heritable morphological variation in a natural population of song sparrows.		1980	28568465
early perceptual selectivity in the swamp sparrow.	the cardiac orienting response to species-specific songs was measured in young swamp sparrows and song sparrows. swamp sparrows respond with significantly greater deceleration to conspecific songs than to songs of the sympatric song sparrow. this discriminatory ability is operating during the sensitive period for song learning and is evident upon initial exposures to conspecific song. these results are the 1st direct evidence for a sensory component in the process of selective vocal learning in ...	1980	7409330
a winter feeding experiment on an island song sparrow population.	supplemental food, in the form of millet seed, was provided to half of an island song sparrow population during the 1978-1979 winter to test if winter food influenced: (1) overwinter survival; (2) winter wights; (3) breeding density in 1979 and (4) 1979 breeding performance.territorial males were most dominant at feeders and may have restricted access of young to feeders. young females were most subordinate at feeders. adult survival was not affected by supplementary food, but young survival was ...	1980	28309466
temporal spacing of broods, brood size, and parental care in song sparrows (melospiza melodia).		1980	7427795
does high fecundity reduce survival in song sparrows?		1981	28563403
a test for responsiveness to song structure and programming in female sparrows.	female song sparrows, primed with implants of estradiol, gave the solicitation display for copulation in response to acoustic stimulation with song. this technique demonstrated that female song sparrows respond more strongly to conspecific song than to alien songs, that they discriminate on the basis of both overall temporal pattern and syllabic structure, that they respond more to several song types than to repetitions of one song, and that they are most responsive to several song types if the ...	1981	17775278
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 ...	1983	6827307
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, ...	1984	6510698
environmental and endocrine control of reproduction in the song sparrow, melospiza melodia. ii. agonistic interactions as environmental information stimulating secretion of testosterone.	a group of eight free-living adult male song sparrows, selected at random, were given subcutaneous implants of testosterone (t) in silastic tubing. in a separate area, 1 km distant, a second group of eight free-living males were given empty implants as controls. all implants were administered in late march and early april and in the experimental group maintained plasma levels of t at the springtime peak. to test whether prolonged high levels of t maintained aggressive territorial behavior at the ...	1984	6542537
validation of the doubly labeled water technique for measuring energy metabolism in starlings and sparrows.	i have tested the idea that doubly labeled water (dlw) can accurately predict co2 production in savannah sparrows, song sparrows, white-throated sparrows, starlings, and a single house sparrow by comparing dlw estimates with those obtained simultaneously by capturing expired co2 in ascarite. in addition i used the energy balance method to see if metabolic rates generated from dlw measurements accurately reflected the actual metabolic rates of these birds. i found close agreement in dlw and the g ...	1985	2858313
short-term changes in plasma levels of hormones during establishment and defense of a breeding territory in male song sparrows, melospiza melodia.	when territorial male song sparrows are captured and removed from their territories, previously unmated and nonterritorial males will take over those vacant territories within 12-72 hr. plasma levels of testosterone are elevated in these replacement males as well as in their neighbors. since the latter already have territories, it is suggested that the agonistic interactions over territory boundaries, or behavioral stimuli from challenging males, rather than ownership of a territory per se, stim ...	1985	4040115
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 ...	1986	28556039
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 ...	1987	3568610
response of sparrows to songs of deaf and isolation-reared males: further evidence for innate auditory templates.	adult song sparrows (melospiza melodia) were tested for response to songs of conspecific males that had been reared in acoustic isolation or deafened early in life. territorial males responded more aggressively to playback of songs of isolated males than to songs of deafened males but did not discriminate between songs of deafened males and heterospecific songs. captive females showed an identical pattern when their response was measured in terms of the number and intensity of courtship displays ...	1987	3678616
song syllable discrimination by song sparrows (melospiza melodia).	a habituation test paradigm was used to examine the responses of free-living territorial adult male song sparrows (melospiza melodia) to a range of synthetic songs. the three-phrased test songs differed from one another in having either conspecific or heterospecific (swamp sparrow, m. georgiana) syllables, or silence, in the second phrase. subjects were exposed to repeated presentations of one song type until their approach distance to a loudspeaker increased. in one experiment, birds were habit ...	1987	3568605
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 ...	1988	3282980
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- ...	1988	2452178
retinohypothalamic projections and the suprachiasmatic nucleus in birds.	although many investigators have examined retinal projections in birds, there is uncertainty as to the location and identity of a retinorecipient nucleus in the hypothalamus of aves. a direct retinohypothalamic projection to the medial hypothalamic suprachiasmatic nucleus in mammals is believed to play a role in the entrainment of circadian rhythms. a direct retinohypothalamic projection could subserve a similar function in birds. in the present experiment, horseradish peroxidase, injected intra ...	1989	2819412
testosterone induction of song in photosensitive and photorefractory male sparrows.	song in male songbirds is activated by the sex steroid testosterone (t). using male song sparrows (melospiza melodia), we compared effects of t in the normal spring state of photosensitivity (i.e., when the pituitary-gonadal axis is sensitive to stimulation by increasing daylength) and in the late summer-early fall state of photorefractoriness (i.e., when they are insensitive to increasing daylength). photosensitive males experienced short days for 8 weeks and then long days for another 22 weeks ...	1989	2606465
immunohistochemical localization of corticotropin-releasing factor in selected brain areas of the european starling (sturnus vulgaris) and the song sparrow (melospiza melodia).	corticotropin-releasing factor (crf) was localized in the brains of two passerine species, the european starling (sturnus vulgaris) and the song sparrow (melospiza melodia), by means of immunohistochemistry. the hypothalamic distribution of this peptide in these species includes a complex of immunoreactive perikarya observed in the paraventricular nucleus (pvn), in both its medial and lateral divisions. nerve fibers were also seen running from these areas to the anterior median eminence (ame) wh ...	1989	2787697
plasma levels of prolactin and gonadal steroids in relation to multiple-brooding and renesting in free-living populations of the song sparrow, melospiza melodia.	plasma levels of testosterone (t), estradiol (e2), and prolactin were measured in samples collected from free-living song sparrows, melospiza melodia. in males, plasma levels of t were elevated early in the season when territories were established and when females laid the first clutch of eggs. thereafter, t levels declined and remained low throughout the remainder of the breeding cycle. however, if the first brood was lost to a predator, or by experimental removal of the nest, plasma levels of ...	1990	2328972
natural selection on bill characters in the two bill morphs of the african finch pyrenestes ostrinus.	evidence for natural selection on seven bill and body characters is examined in the two bill morphs of the african estrildid finch pyrenestes ostrinus. two regression methods are used in examining natural selection in association with survivorship: a parametric (lande and arnold, 1983) and a non-parametric (schluter, 1988) method. selection was estimated in adult males, females and juveniles over a four-year period in a population in south-central cameroon. selection was common among groups but ...	1990	28569017
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 ...	1990	2229474
avian seed preference and weight loss experiments: the effect of fungal endophyte-infected tall fescue seeds.	the impact of endophytic fungus-infected seeds on seed predators is poorly understood. in this multiple trophic level investigation, seed preference experiments were conducted to determine whether five species of passerines (dark-eyed juncos, junco hyemalis; american tree sparrows, spizella arborea; song sparrows, melospiza melodia; chipping sparrows, spizella pusilla; and house sparrows, passer domesticus) recognize and preferentially consume noninfected (ni) over infected (i) seeds of tall fes ...	1991	28312146
the geography of mitochondrial dna variation in two sympatric sparrows.	geographic variation in mitochondrial dna (mtdna) restriction sites was studied in samples of two sympatric passerine birds, fox (passerella iliaca) and song (melospiza melodia) sparrows, collected at the same sites in the western united states. different levels of variation and differentiation were observed in each species. in 46 fox sparrows taken at nine sites, five clones were observed, partitioned into two distinct east-west groups that meet at the great basin-sierra nevada interface; perce ...	1991	28567872
long-term enhancement of synaptic responses in the songbird hippocampus.	electrophysiological recordings from the hippocampus were taken using brain slices from 1-year-old, female, song sparrows (melospiza melodia). the evoked responses were smaller and less stable as compared with those obtained from the mammalian hippocampus. they consisted of two spikes. the first spike had low calcium dependency and represented mainly fiber potential. the second spike demonstrated a clear calcium dependency proving its synaptic origin. paired-pulse facilitation showed inhibition ...	1991	2018921
responses to a simple habitat cue in naive swamp and song sparrows.		1992	28313066
control of testicular cycles in the song sparrow, melospiza melodia melodia: interaction of photoperiod and an endogenous program?	adult male song sparrows, melospiza melodia melodia, underwent testicular development accompanied by increases in plasma levels of follicle-stimulating hormone (fsh) and luteinizing hormone (lh) regardless of photoperiods tested. although gonadal development progressed rapidly in birds exposed to long days, males subjected to short day lengths also showed testicular growth between 90 and 200 days. onset of photorefractoriness during exposure to continual long days was highly variable among indiv ...	1993	8138105
gene flow, refugia, and evolution of geographic variation in the song sparrow (melospiza melodia).	we surveyed mtdna restriction-site variation in song sparrows taken from across their continental range. despite marked geographic variation in size and plumage color, mtdna variation was not geographically structured. subspecies were not identifiable by mtdna analysis. we suggest that postglaciation dispersal scattered mtdna haplotypes across the continent, explaining the lack of mtdna geographic patterns. evolution of size and plumage coloration has probably proceeded faster than mtdna evoluti ...	1993	28567898
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 ...	1993	8370728
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 ...	1994	7969492
regulation of territorial behavior in the sedentary song sparrow, melospiza melodia morphna.	male song sparrows (melospiza melodia morphna) of western washington state show year-round territoriality. although territorial aggression during the breeding season was accompanied by high circulating levels of luteinizing hormone (lh) and testosterone (t), similar aggression in the non-breeding season occurred when gonadal hormone levels were basal. experimental removal of territorial males in autumn resulted in new males taking over the territory within a few days. these males had basal level ...	1994	8034278
behavioral and hormonal responses of male song sparrows to estradiol-treated females during the non-breeding season.	previous studies on several species have shown that behavior of female vertebrates given estradiol implants to maintain sexual receptivity resulted in elevated levels of testosterone in males and even delayed termination of breeding in their otherwise untreated mates. however, the efficacy of such treatment in the non-breeding season was unclear. in this study, female song sparrows, melospiza melodia morphna, given implants of estradiol in autumn showed elevated sexual behavior--especially "chit ...	1994	7927281
correlation of song learning and territory establishment strategies in the song sparrow.	in a field study, we show that a young song sparrow (i) selects his songs from three or four older birds who have neighboring territories, (ii) preferentially learns song types that these tutor neighbors share, and (iii) ultimately sets up his territory next to, or replaces, one of these tutor neighbors. the consequence of this song learning strategy is that the young bird's song repertoire represents the "logical intersection" of the song repertoires of his tutor neighbors. we argue that this r ...	1994	11607460
control of territorial aggression in a changing environment.	a sedentary population of song sparrows, melospiza melodia morphna, in western washington state shows year-round territoriality but in different contexts. during the breeding season (march-august), all defend multiple purpose territories as monogamous pairs, or alone, but only about 30% of individuals remain on the same territory during the nonbreeding season (september-february). during the breeding season, territorial behavior is tightly correlated with circulating levels of luteinizing hormon ...	1994	7938366
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 ...	1995	24197796
effects of granular formulations of terbufos and fonofos applied to cornfields on mortality and reproductive success of songbirds.	: this field study used a precise method of assessing effects of insecticides on bird populations by establishing a marked population before application and determining survival rates of known individuals after application of the insecticides. we investigated the effects of two organophosphate granular insecticides applied to cornfields in southwestern ontario to combat the corn rootworm (diabrotica spp.). nine control fields and 11 treated fields, six of which were treated with fonofos (dyfonat ...	1995	24197620
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 ...	1996	28568862
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- ...	1996	11607677
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 ...	1997	9386917
seasonal changes in testosterone, neural attributes of song control nuclei, and song structure in wild songbirds.	seasonal changes in the neural attributes of brain nuclei that control song in songbirds are among the most pronounced examples of naturally occurring plasticity in the adult brain of any vertebrate. the behavioral correlates of this seasonal neural plasticity have not been well characterized, particularly in songbird species that lack adult song learning. to address this question, we investigated the relationship between seasonal changes in gonadal steroids, song nuclei, and song behavior in ad ...	1997	9221796
host responses to cowbirds near the nest: cues for recognition	two cues (bill shape and vocalizations) that yellow warblers, dendroica petechiamay use to recognize brown-headed cowbirds, molothrus aterwere examined experimentally. female yellow warblers responded more intensely to a control cowbird than one with a longer, thinner bill, which suggests that bill shape was an important cue in recognition. responses involved close approaches, 'seet' alarm calls and sitting in the nest. female yellow warblers distinguished between vocalizations of male and femal ...	1997	9236024
brain gene regulation by territorial singing behavior in freely ranging songbirds.	to investigate the ecological relevance of brain gene regulation associated with singing behavior in songbirds, we challenged freely ranging song sparrows with conspecific song playbacks within their breeding territories. males responded by approaching the speaker, searching for an intruder and actively singing. in situ hybridization of brain sections revealed significantly higher expression of the transcriptional regulator zenk in challenged birds than in unstimulated controls in several audito ...	1997	9223104
inbreeding and its fitness effects in an insular population of song sparrows (melospiza melodia).	inbreeding depression is thought to be a major factor affecting the evolution of mating systems and dispersal. while there is ample evidence for inbreeding depression in captivity, it has rarely been documented in natural populations. in this study, i examine data from a long-term demographic study of an insular population of song sparrows (melospiza melodia) and present evidence for inbreeding depression. forty-four percent of all matings on mandarte island, british columbia, were among known r ...	1998	28568167
geographic analysis of nucleotide diversity and song sparrow (aves: emberizidae) population history.	mitochondrial dna (mtdna) control-region (cr) sequences were analysed to address three questions regarding the evolution of geographical variation in song sparrows. (i) are mtdna sequences more informative about phylogenetic relationships and population history than previously published restriction fragment (rflp) data? (ii) are song sparrow cr sequences evolving in a selectively neutral manner? (iii) what do the haplotype cladogram and geographical pattern of nucleotide diversity (pi) suggest a ...	1998	9787442
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 ...	1998	28308530
no evidence for inbreeding avoidance in a natural population of song sparrows (melospiza melodia).	we studied mate choice and inbreeding avoidance a natural population of song sparrows (melospiza melodia) on mandarte island, canada. inbreeding occurred regularly: 59% all matings were between known relatives. we tested for inbreeding avoidance by comparing the observed levels of inbreeding to those expected if mate choice had been random with respect to relatedness. independent of our assumptions about the availability of mates in the random mating model, we found that the expected and observe ...	1998	18811446
song types as fundamental units in vocal repertoires.	we investigated whether song types function as fundamental units of song variation in song sparrows, melospiza melodia. as the size of a male song sparrow's repertoire increases, so does the mean similarity of his song types, as measured by the sharing of minimal units of production (mups). it follows that if mup similarity is important perceptually, then small repertoires (of dissimilar song types) may be functionally equivalent to large repertoires (of similar song types). we performed two exp ...	1999	10413538
mate, neighbour and stranger songs: a female song sparrow perspective.	we investigated discrimination by female song sparrows melospiza melodia, between different categories of male song using the copulation solicitation display as a preference assay. females responded most strongly to songs recorded from their mates, less strongly to songs of neighbouring males and least strongly to songs of stranger males. among the stranger songs, however, females preferred songs that were most similar structurally to song types in their mates' repertoires (matching songs). thes ...	1999	10413536
the development of within-song type variation in song sparrows.	we investigated the development of within-song type variation in song sparrows, melospiza melodia, with two experiments designed to determine how exposure to within-type variation influences the song-learning process and whether within-type variation itself is a learned trait. in the first experiment, we compared learning between two groups of males, one group tutored exclusively with song models presented with no variation, and the other group tutored exclusively with song models presented with ...	1999	10373259
combined aromatase inhibitor and antiandrogen treatment decreases territorial aggression in a wild songbird during the nonbreeding season.	male song sparrows (melospiza melodia morphna) defend territories throughout the year in western washington state. in the nonbreeding season (autumn and winter), aggression and song are robustly expressed but plasma testosterone (t) levels are basal. also, castration does not decrease nonbreeding territoriality. in this field experiment, we asked whether nonbreeding aggression is independent of t. t can act via androgen receptors or t can be aromatized to 17beta-estradiol (e(2)) and act via estr ...	1999	10480996
a field study of seasonal neuronal incorporation into the song control system of a songbird that lacks adult song learning.	adult songbirds can incorporate new neurons into hvc, a telencephalic song control nucleus. neuronal incorporation into hvc is greater in the fall than in the spring in adult canaries (open-ended song learners) and is temporally related to seasonal song modification. we used the western song sparrow, a species that does not modify its adult song, to test the hypothesis that neuronal incorporation into adult hvc is not seasonally variable in age-limited song learners. wild song sparrows were capt ...	1999	10440732
estimating the time to extinction in an island population of song sparrows.	we estimated and modelled how uncertainties in stochastic population dynamics and biases in parameter estimates affect the accuracy of the projections of a small island population of song sparrows which was enumerated every spring for 24 years. the estimate of the density regulation in a theta-logistic model (theta = 1.09 suggests that the dynamics are nearly logistic, with specific growth rate r1 = 0.99 and carrying capacity k = 41.54. the song sparrow population was strongly influenced by demo ...	2000	10787168
female song sparrow, melospiza melodia, response to simulated conspecific and heterospecific intrusion across three seasons.	to investigate female responses to territorial intrusion i presented female song sparrows with either a simulated female song sparrow intrusion or a simulated spotted towhee, pipilo maculatus, intrusion as a control during either the prebreeding, breeding or postmoult seasons. aggressive and nonaggressive behaviours and vocalizations were compared between intrusion types and across seasons. principle components analysis suggested that female responses fell into three categories: (1) responses di ...	2000	10715177
renal anatomy in sparrows from different environments.	the renal anatomy of three species of sparrows, two from mesic areas, the house sparrow (passer domesticus) and song sparrow (melospiza melodia), and one salt marsh species, the savannah sparrow (passerculus sandwichensis) was examined. electron microscopy was used to describe the ultrastructure of the nephron. in addition, stereology was used to quantify the volumes of cortex, medulla, and major vasculature of the kidneys, and the volumes and surface areas occupied by individual nephron compone ...	2000	10681473
territory tenure in song sparrows is related to song sharing with neighbours, but not to repertoire size.	song repertoires may be a product of sexual selection and several studies have reported correlations of repertoire size and reproductive success in male songbirds. this hypothesis and the reported correlations, however, are not sufficient to explain the observation that most species have small song repertoire sizes (usually fewer than 10, often fewer than five song types). we examined a second important aspect of a male's song repertoire, the extent to which he shares songs with his neighbours. ...	2000	10640364
song-type matching between neighbouring song sparrows.	in our study population, neighbouring song sparrows typically share two or more of their 6-10 song types. in an earlier experiment, we found that established neighbours typically reply to playback of neighbour-shared song with a different song they share with that neighbour ('repertoire matching'), rather than with the same song ('type matching') or with a nonshared song. in the present experiment, we considered the hypothesis that type matching is a threat or warning signal (krebs et al. 1981, ...	2000	10640363
social influences during song development in the song sparrow: a laboratory experiment simulating field conditions.	oscine songbirds are exposed to many more songs than they keep for their final song repertoire and little is known about how a bird selects the particular song(s) to sing as an adult. we simulated in the laboratory the key variables of the natural song learning environment and examined the song selection process in nine hand-reared male song sparrows, melospiza melodia, a species in which males sing 5-11 song types. during their second and third months (their presumed sensitive period), subjects ...	2000	10877898
stimulatory effects on the reproductive axis in female songbirds by conspecific and heterospecific male song.	courtship vocalizations of male songbirds can profoundly enhance the reproductive physiology and behavior of conspecific females. however, no study has fully investigated the selectivity of conspecific song effects on reproductive development in birds. we studied the effects of conspecific and heterospecific song on reproductive development in domesticated (canaries) and wild songbirds (song sparrows). as expected, conspecific song enhanced follicular development. unexpectedly, however, birds ex ...	2000	10868481
oestrogen regulates male aggression in the non-breeding season.	extensive research has focused on territorial aggression during the breeding season and the roles of circulating testosterone (t) and its conversion to 17beta-oestradiol (e2) in the brain. however, many species also defend territories in the non-breeding season, when circulating t-levels are low. the endocrine control of non-breeding territoriality is poorly understood. the male song sparrow of washington state is highly territorial year-round, but plasma t is basal in the non-breeding season (a ...	2000	10885513
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 ...	2000	10623896
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 ...	2001	11476328
seasonal growth of song control nuclei precedes seasonal reproductive development in wild adult song sparrows.	in seasonally breeding adult songbirds, the brain regions that control song undergo dramatic seasonal morphological changes. during late winter and early spring, increasing day length triggers an increase in circulating testosterone that ultimately causes several song nuclei to grow in volume. the timing of this growth relative to the seasonal development of the reproductive system is not known. this question was investigated in two populations of wild song sparrows (melospiza melodia morphna). ...	2001	11352547
is song-type matching a conventional signal of aggressive intentions?	song-type matching is a singing strategy found in some oscine songbirds with repertoires of song types and at least partial sharing of song types between males. males reply to the song of a rival male by subsequently singing the same song type. for type matching to serve as an effective long-distance threat signal, it must be backed up by some probability of aggressive approach and impose some type of cost on senders that minimizes the temptation to bluff. western subspecies of the song sparrow ...	2001	11487412
dehydroepiandrosterone in songbird plasma: seasonal regulation and relationship to territorial aggression.	many male animals are territorial in the breeding season, when plasma testosterone (t) levels are high, and nonterritorial in the nonbreeding season, when plasma t levels are basal. in contrast to this common pattern, male song sparrows (melospiza melodia morphna) are territorial year-round, except briefly during molt. song sparrows are highly aggressive in the nonbreeding season (autumn and winter), even though plasma t, 5 alpha-dihydrotestosterone, androstenedione (ae), and 17beta-estradiol le ...	2001	11482935
hippocampal volume does not change seasonally in a non food-storing songbird.	seasonal differences in hippocampal morphology have been reported in food-storing birds. non food-storing species have not been investigated however. it is therefore unclear whether seasonal changes in the hippocampus are specifically related to food-storing or reflect a more general seasonal mechanism that occurs in both food-storing and non food-storing birds alike. we determined the volumes of the hippocampal formation and remaining telencephalon in the non-storing male song sparrow (melospiz ...	2001	11435924
immigration and the ephemerality of a natural population bottleneck: evidence from molecular markers.	population bottlenecks are often invoked to explain low levels of genetic variation in natural populations, yet few studies have documented the direct genetic consequences of known bottlenecks in the wild. empirical studies of natural population bottlenecks are therefore needed, because key assumptions of theoretical and laboratory studies of bottlenecks may not hold in the wild. here we present microsatellite data from a severe bottleneck (95% mortality) in an insular population of song sparrow ...	2001	11429139
comparative approaches to avian song system function: insights into auditory and motor processing.	many fundamental advances in our understanding of basic neural function have been made using bird song learning and performance as a model system. these advances have included a greater understanding of higher-order neural processing, developmental and hormonal influences on behavior, and the realization that neurogenesis plays an important role in normal adult brain function. the great diversity of passerine birds and song-related behaviors they exhibit suggest that oscine songbirds are ideally ...	2002	12471492
quality of song learning affects female response to male bird song.	bird song is unusual as a sexually selected trait because its expression depends on learning as well as genetic and other environmental factors. prior work has demonstrated that males who are deprived of the opportunity to learn produce songs that function little if at all in male-female interactions. we asked whether more subtle variation in male song-learning abilities influences female response to song. using a copulation solicitation assay, we measured the response of female song sparrows (m ...	2002	12350258
heterosis and outbreeding depression in descendants of natural immigrants to an inbred population of song sparrows (melospiza melodia).	we studied heterosis and outbreeding depression among immigrants and their descendants in a population of song sparrows on mandarte island, canada. using data spanning 19 generations, we compared survival, seasonal reproductive success, and lifetime reproductive success of immigrants, natives (birds with resident-hatched parents and grandparents), and their offspring (f1s, birds with an immigrant and a native parent, and f2s, birds with an immigrant grandparent and resident-hatched grandparent i ...	2002	11913658
spring and autumn territoriality in song sparrows: same behavior, different mechanisms?	vertebrates show a diverse array of social behaviors associated with territoriality. field and laboratory experiments indicate that underlying themes-including mechanisms-may exist. for example in birds, extensive evidence over many decades has implicated a role for testosterone in the activation of territorial aggression in reproductive contexts. territoriality at other times of the year appeared to be independent of gonadal hormone control. one obvious question is-why this diversity of control ...	2002	21708690
dehydroepiandrosterone (dhea) increases territorial song and the size of an associated brain region in a male songbird.	in many species, male territorial aggression is tightly coupled with gonadal secretion of testosterone (t). in contrast, in song sparrows (melospiza melodia morphna), males are highly aggressive during the breeding (spring) and nonbreeding (autumn and early winter) seasons, but not during molt (late summer). in aggressive nonbreeding song sparrows, plasma t levels are basal (< or = 0.10 ng/ml), and castration has no effect on aggression. however, aromatase inhibitors reduce nonbreeding aggressio ...	2002	11855905
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 ...	2002	12357285
geographic song discrimination in relation to dispersal distances in song sparrows.	whether geographic variation in signals actually affects communication between individuals depends on whether discriminable differences in signals occur over distances that individuals move in their lifetimes. we measure the ability of song sparrows (melospiza melodia) to discriminate foreign from local songs using foreign songs recorded at a series of increasing distances and compare the results with previous measurements of dispersal distances. we test discrimination in males using playback of ...	2002	18707375
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 ...	2003	14765678
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 ...	2003	12834441
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 ...	2003	12826417
morphological and microsatellite differentiation in melospiza melodia (aves) at a microgeographic scale.	geographical variation in microsatellite allele frequencies and morphology were compared for five subspecies of melospiza melodia (song sparrow; m. m. samuelis, m. m. maxillaris, m. m. pusillula, m. m. gouldii, and m. m. heermanni) in 14 populations in the san francisco bay region to (a) assess divergence based on these estimates and (b) test the hypothesis that drift is responsible for morphological and genetic divergence. morphological differentiation between subspecies was high despite low di ...	2003	14635909
inbreeding depresses immune response in song sparrows (melospiza melodia): direct and inter-generational effects.	a thorough knowledge of relationships between host genotype and immunity to parasitic infection is required to understand parasite-mediated mechanisms of genetic and population change. it has been suggested that immunity may decline with inbreeding. however, the relationship between inbreeding level and a host's response to a novel immune challenge has not been investigated in a natural population. we used the pedigreed population of song sparrows (melospiza melodia) inhabiting mandarte island, ...	2003	14561279
effects of acute treatment with 8-oh-dpat and fluoxetine on aggressive behaviour in male song sparrows (melospiza melodia morphna).	the role of serotonin in modulating male aggressive behaviour was investigated in male song sparrows, melospiza melodia morphna, using two different serotonergic drugs, fluoxetine and 8-oh-dpat. fluoxetine is a selective serotonin reuptake inhibitor of the neuronal reuptake pump increasing synaptic concentrations of serotonin, and 8-oh-dpat is a specific serotonin (5-ht1a) receptor agonist. the serotonergic control of aggression in passerines has not been previously investigated. we examined the ...	2003	12535157
seasonal changes in avian song control circuits do not cause seasonal changes in song discrimination in song sparrows.	in seasonally breeding songbirds, brain nuclei of the song control system that act in song perception change in size between seasons. it has been hypothesized that seasonal regression of song nuclei may impair song discrimination. we tested this hypothesis in song sparrows (melospiza melodia), a species in which males share song types with neighbors and must discriminate between similar songs in territorial interactions. we predicted that song sparrows with regressed song systems would have grea ...	2003	14556278
el niño drives timing of breeding but not population growth in the song sparrow (melospiza melodia).	increasing evidence suggests that climate change affects the timing of breeding in birds, but there is less evidence to show how such changes affect the population dynamics of birds overall. over the past 43 years, song sparrows (melospiza melodia) on mandarte island, british columbia, canada have not shown an advance in breeding date in response to global warming. however, this population did show considerable annual variation in timing of breeding correlated with the el niño southern oscillati ...	2003	12960365
brain aromatase, 5 alpha-reductase, and 5 beta-reductase change seasonally in wild male song sparrows: relationship to aggressive and sexual behavior.	in many species, territoriality is expressed only during the breeding season, when plasma testosterone (t) is elevated. in contrast, in song sparrows (melospiza melodia morphna), males are highly territorial during the breeding (spring) and nonbreeding (autumn) seasons, but not during molt (late summer). in autumn, plasma sex steroids are basal, and castration has no effect on aggression. however, inhibition of aromatase reduces nonbreeding aggression, suggesting that neural steroid metabolism m ...	2003	12884261
fos-like immunoreactivity in catecholaminergic brain nuclei after territorial behavior in free-living song sparrows.	the catecholaminergic cell groups of the brainstem play an important role in the regulation of motivated behavior, including reproductive behavior. in songbirds, these cell groups project to telencephalic nuclei involved in singing and contain steroid hormone receptors, implicating them in the seasonal regulation of song. whether these nuclei are involved in the activation of song on a short-term, moment-to-moment basis is unknown. in this study, free-living male song sparrows (melospiza melodia ...	2003	12838581
synergistic effects of food and predators on annual reproductive success in song sparrows.	the behaviour literature is full of studies showing that animals in every taxon balance the probability of acquiring food with the risk of being preyed upon. while interactions between food and predators clearly operate at an individual scale, population-scale studies have tended to focus on only one factor at a time. consequently, interactive (or 'synergistic') effects of food and predators on whole populations have only twice before been experimentally demonstrated in mammals. we conducted a 2 ...	2003	12737657
balancing food and predator pressure induces chronic stress in songbirds.	the never-ending tension between finding food and avoiding predators may be the most universal natural stressor wild animals experience. the 'chronic stress' hypothesis predicts: (i) an animal's stress profile will be a simultaneous function of food and predator pressures given the aforesaid tension; and (ii) these inseparable effects on physiology will produce inseparable effects on demography because of the resulting adverse health effects. this hypothesis was originally proposed to explain sy ...	2004	15590598
habitat selection, acoustic adaptation, and the evolution of reproductive isolation.	we examined barriers to gene flow in a hybrid zone of two subspecies of the song sparrow (melospiza melodia). we focused on how mating signals and mate choice changed along an environmental gradient and gathered data on the morphology, genetics, ecology, and behavior across the zone. melospiza m. heermanni of the pacific slope of california and m. m. fallax of the sonoran desert, each distinct in plumage, meet across a steep environmental gradient in southeastern california. although both subspe ...	2004	15562681
neural responses to territorial challenge and nonsocial stress in male song sparrows: segregation, integration, and modulation by a vasopressin v1 antagonist.	the present experiments were conducted to determine (1) which basal forebrain regions and/or their peptidergic components are responsive to social challenge and nonsocial stress, and (2) the influence of an arginine vasopressin v(1) antagonist (avpa) on these responses. experiments were conducted in wild-caught male song sparrows (melospiza melodia) that were housed on seminatural territories (field-based flight cages). subjects were each fitted with a chronic guide cannula directed at the later ...	2004	15465522
androgens and the immunocompetence handicap hypothesis: unraveling direct and indirect pathways of immunosuppression in song sparrows.	the immunocompetence handicap hypothesis proposes that testosterone (t)-dependent sexual signals are honest indicators of male health or genetic quality because only high-quality males are able to withstand the obligate effects of t-induced immunosuppression. in birds, the basic assumption that t suppresses immune function is equivocal, and the physiological mechanisms underlying t-induced immunosuppression remain to be investigated. we explored the proximate pathways of t-induced immunosuppress ...	2004	15459880
reproductive development according to elevation in a seasonally breeding male songbird.	seasonal temperate zone breeders respond to increasing day length to anticipate the approach of spring breeding conditions. other (supplementary) environmental cues, such as temperature and precipitation, were historically thought to play unimportant roles in reproductive timing. we demonstrate variation in reproductive timing across small geographic distances by examining the vernal testicular recrudescence of adult song sparrows (melospiza melodia morphna) breeding in coastal (0-10 m elevation ...	2004	15148599
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 ...	2004	15286416
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 ...	2004	15056696
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