| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| responses to a simple habitat cue in naive swamp and song sparrows. | | 1992 | 28313066 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| heritability of some morphological characters in a song sparrow population. | | 1979 | 28568196 |
| 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 |
| competitive release in island song sparrow populations. | | 1974 | 4818407 |
| variation in blood group frequencies in populations of song sparrows of the san francisco bay region. | | 1966 | 28562979 |
| development of the corticosterone stress response differs among passerine species. | glucocorticoids are steroid hormones which increase dramatically in response to a physical or perceived stressor. however, developing young of altricial species typically have a damped glucocorticoid stress response. the developmental hypothesis posits that the physiological stress response should develop concurrently with an individual's ability to respond to a challenge. the dampened response may benefit an organism, as chronic exposure to glucocorticoids can have short- and long-term detrimen ... | 2020 | 32027877 |
| avian malaria co-infections confound infectivity and vector competence assays of plasmodium homopolare. | currently, there are very few studies of avian malaria that investigate relationships among the host-vector-parasite triad concomitantly. in the current study, we experimentally measured the vector competence of several culex mosquitoes for a newly described avian malaria parasite, plasmodium homopolare. song sparrow (melospiza melodia) blood infected with a low p. homopolare parasitemia was inoculated into a naïve domestic canary (serinus canaria forma domestica). within 5 to 10 days post infec ... | 2018 | 29845414 |
| bird species involved in west nile virus epidemiological cycle in southern québec. | despite many studies on west nile virus (wnv) in the us, including the reservoir role of bird species and the summer shifts of the culex mosquito, feeding from birds to mammals, there have been few equivalent studies in the neighboring regions of canada where wnv is endemic. here, a priority list of bird species likely involved in wnv transmission in the greater montréal area is constructed by combining three sources of data: (i) from wnv surveillance in wild birds (2002-2015); (ii) blood meal a ... | 2020 | 32585999 |
| postbreeding elevational movements of western songbirds in northern california and southern oregon. | migratory species employ a variety of strategies to meet energetic demands of postbreeding molt. as such, at least a few species of western neotropical migrants are known to undergo short-distance upslope movements to locations where adults molt body and flight feathers (altitudinal molt migration). given inherent difficulties in measuring subtle movements of birds occurring in western mountains, we believe that altitudinal molt migration may be a common yet poorly documented phenomenon. to exam ... | 2017 | 29043031 |
| elevated mercury in blood and feathers of breeding marsh birds along the contaminated lower penobscot river, maine, usa. | mercury (hg) concentrations in the blood and feathers of five species of migratory marsh birds, nelson's sparrow (ammodramus nelson subvirgatus), song sparrow (melospiiza melodia), swamp sparrow (melospiza geogiana), red-winged blackbird (agelaius phoeniceus), and virginia rail (rallus limicola), breeding in marshes along the lower penobscot river, maine, far exceeded reference concentrations, exceeded concentrations associated with reproductive health, and are the highest hg concentrations repo ... | 2018 | 29710654 |
| a high-quality genome assembly of the north american song sparrow, melospiza melodia. | the song sparrow, melospiza melodia, is one of the most widely distributed species of songbirds found in north america. it has been used in a wide range of behavioral and ecological studies. this species' pronounced morphological and behavioral diversity across populations makes it a favorable candidate in several areas of biomedical research. we have generated a high-quality de novo genome assembly of m. melodia using illumina short read sequences from genomic and in vitro proximity-ligation li ... | 2020 | 32075855 |
| influence of the agricultural conservation easement program wetland practices on winter occupancy of passerellidae sparrows and avian species richness. | wetlands enrolled in the agricultural conservation easement program (acep) are established as a means of restoring wetland ecosystems and wildlife habitat on private, agricultural land. in west virginia, usa, acep wetlands have never been evaluated to determine how they function as wildlife habitat in comparison to other available wetland habitat in the state. we measured the wintering occupancy of passerellidae species and apparent avian species richness on acep wetlands and a set of reference ... | 2019 | 30677050 |
| wax ester composition of songbird preen oil varies seasonally and differs between sexes, ages, and populations. | chemical signaling has been well studied in invertebrates and mammals but less so in birds, due to the longstanding misconception that olfaction is unimportant or even non-existent in this taxon. however, recent findings suggest that olfaction plays an important role in avian mate choice and reproductive behavior, similar to other taxa. the leading candidate source for compounds involved in avian chemical communication is preen oil, a complex mixture secreted from the uropygial gland. preen oil ... | 2019 | 30456558 |
| demographic consequences of invasion by a native, controphic competitor to an insular bird population. | species invasions and range shifts can lead to novel competitive interactions between historically resident and colonizing species, but the demographic consequences of such interactions remain controversial. we present results from field experiments and 45 years of demographic monitoring to test the hypothesis that the colonization of mandarte is., bc, canada, by fox sparrows (passerella iliaca) caused the long-term decline of the resident population of song sparrows (melospiza melodia). several ... | 2018 | 29500488 |
| rapid effects of 17β-estradiol on aggressive behavior in songbirds: environmental and genetic influences. | contribution to special issue on fast effects of steroids. 17β-estradiol (e2) has numerous rapid effects on the brain and behavior. this review focuses on the rapid effects of e2 on aggression, an important social behavior, in songbirds. first, we highlight the contributions of studies on song sparrows, which reveal that seasonal changes in the environment profoundly influence the capacity of e2 to rapidly alter aggressive behavior. e2 administration to male song sparrows increases aggression wi ... | 2018 | 29605636 |
| genomic differentiation and local adaptation on a microgeographic scale in a resident songbird. | elucidating forces capable of driving species diversification in the face of gene flow remains a key goal in evolutionary biology. song sparrows, melospiza melodia, occur as 25 subspecies in diverse habitats across north america, are among the continent's most widespread vertebrate species, and are exemplary of many highly variable species for which the conservation of locally adapted populations may be critical to their range-wide persistence. we focus here on six morphologically distinct subsp ... | 2020 | 32978972 |
| social factors in bird-song development: learning to sing with friends and rivals. | laboratory studies have revealed that social factors are key in bird-song learning. nevertheless, little is known about how or why birds choose the songs they do learn from the many they will hear under natural conditions. we focus on various theories concerning social song learning that have been offered to date, with special attention paid to two axes of social factors. first, does song learning occur via direct interaction of the young bird with song tutors, or via social eavesdropping by the ... | 2020 | 32820427 |
| song sparrows do not discriminate between their own song and stranger song. | bird song is socially learned. during song learning, the bird's hearing its own vocalization is important for normal development of song. whether bird's own song is represented and recognized as a special category in adult birds, however, is unclear. if birds respond differently to their own songs when these are played back to them, this would be evidence for auditory self-recognition. to test this possibility, we presented song sparrow males (melospiza melodia) playbacks of their own songs or s ... | 2020 | 32561233 |
| effects of low-density urbanization on genetic structure in the song sparrow. | urbanization fragments landscapes and can impede the movement of organisms through their environment, which can decrease population connectivity. reduction in connectivity influences gene flow and allele frequencies, and can lead to a reduction in genetic diversity and the fixation of certain alleles, with potential negative effects for populations. previous studies have detected effects of urbanization on genetic diversity and structure in terrestrial animals living in landscapes that vary in t ... | 2020 | 32530950 |
| birds suppress pests in corn but release them in soybean crops within a mixed prairie/agriculture system. | birds provide ecosystem services (pest control) in many agroecosystems and have neutral or negative ecological effects (disservices) in others. large-scale, conventional row crop agriculture is extremely widespread globally, yet few studies of bird effects take place in these agroecosystems. we studied indirect effects of insectivorous birds on corn and soybean crops in fields adjacent to a prairie in illinois (usa). we hypothesized that prairie birds would forage for arthropods in adjacent crop ... | 2020 | 32476673 |
| recent immigrants alter the quantitative genetic architecture of paternity in song sparrows. | quantifying additive genetic variances and cross-sex covariances in reproductive traits, and identifying processes that shape and maintain such (co)variances, is central to understanding the evolutionary dynamics of reproductive systems. gene flow resulting from among-population dispersal could substantially alter additive genetic variances and covariances in key traits in recipient populations, thereby altering forms of sexual conflict, indirect selection, and evolutionary responses. however, t ... | 2020 | 32313688 |
| food stress, but not experimental exposure to mercury, affects songbird preen oil composition. | mercury is a global pollutant and potent neurotoxic metal. its most toxic and bioavailable form, methylmercury, can have both lethal and sublethal effects on wildlife. in birds, methylmercury exposure can disrupt behavior, hormones, the neuroendocrine system, and feather integrity. lipid-rich tissues and secretions may be particularly susceptible to disruption by lipophilic contaminants such as methylmercury. one such substance is feather preen oil, a waxy secretion of the uropygial gland that s ... | 2020 | 32036507 |
| brain activity underlying american crow processing of encounters with dead conspecifics. | animals utilize a variety of auditory and visual cues to navigate the landscape of fear. for some species, including corvids, dead conspecifics appear to act as one such visual cue of danger, and prompt alarm calling by attending conspecifics. which brain regions mediate responses to dead conspecifics, and how this compares to other threats, has so far only been speculative. using 18f-fluorodeoxyglucose positron emission tomography (fdg-pet) we contrast the metabolic response to visual and audit ... | 2020 | 32035868 |
| perceived wintering latitude determines timing of song output in a migratory bird. | migratory bird populations frequently consist of individuals that overwinter variable distances from the breeding site. seasonal changes in photoperiod, which varies with latitude, underlie seasonal changes in singing frequency in birds. therefore, migratory populations that consist of individuals that overwinter at different latitudes with large overwintering ranges could experience within-population variation in seasonal production of song. to test the influence of overwintering latitude on in ... | 2020 | 32015840 |
| testing predictions of inclusive fitness theory in inbreeding relatives with biparental care. | inclusive fitness theory predicts that parental care will vary with relatedness between potentially caring parents and offspring, potentially shaping mating system evolution. systems with extra-pair paternity (epp), and hence variable parent-brood relatedness, provide valuable opportunities to test this prediction. however, existing theoretical and empirical studies assume that a focal male is either an offspring's father with no inbreeding, or is completely unrelated. we highlight that this sim ... | 2019 | 31795864 |
| multi-modal communication: song sparrows increase signal redundancy in noise. | although the effects of anthropogenic noise on animal communication have been studied widely, most research on the effect of noise in communication has focused on signals in a single modality. consequently, how multi-modal communication is affected by anthropogenic noise is relatively poorly understood. here, we ask whether song sparrows (melospiza melodia) show evidence of plasticity in response to noise in two aggressive signals in acoustic and visual modalities. we test two hypotheses: (i) th ... | 2019 | 31662064 |
| individuals' expected genetic contributions to future generations, reproductive value, and short-term metrics of fitness in free-living song sparrows (melospiza melodia). | appropriately defining and enumerating "fitness" is fundamental to explaining and predicting evolutionary dynamics. yet, general theoretical concepts of fitness are often hard to translate into quantities that can be measured in wild populations experiencing complex environmental, demographic, genetic, and selective variation. although the "fittest" entities might be widely understood to be those that ultimately leave most descendants at some future time, such long-term legacies can rarely be me ... | 2019 | 31171983 |
| measurement of 11-dehydrocorticosterone in mice, rats and songbirds: effects of age, sex and stress. | glucocorticoids (gcs) are secreted into the blood by the adrenal glands and are also locally-produced by organs such as the lymphoid organs (bone marrow, thymus, and spleen). corticosterone is the primary circulating gc in many species, including mice, rats and birds. within lymphoid organs, corticosterone can be locally produced from the inactive metabolite, 11-dehydrocorticosterone (dhc). however, very little is known about endogenous dhc levels, and no immunoassays are currently available to ... | 2019 | 31145891 |
| "balancing" balancing selection? assortative mating at the major histocompatibility complex despite molecular signatures of balancing selection. | in vertebrate animals, genes of the major histocompatibility complex (mhc) determine the set of pathogens to which an individual's adaptive immune system can respond. mhc genes are extraordinarily polymorphic, often showing elevated nonsynonymous relative to synonymous sequence variation and sharing presumably ancient polymorphisms between lineages. these patterns likely reflect pathogen-mediated balancing selection, for example, rare-allele or heterozygote advantage. such selection is often rei ... | 2019 | 31110668 |
| is there indirect selection on female extra-pair reproduction through cross-sex genetic correlations with male reproductive fitness? | one key hypothesis explaining the evolution and persistence of polyandry, and resulting female extra-pair reproduction in socially monogamous systems, is that female propensity for extra-pair reproduction is positively genetically correlated with male reproductive fitness and consequently experiences positive cross-sex indirect selection. however, key genetic correlations have rarely been estimated, especially in free-living populations experiencing natural (co)variation in reproductive strategi ... | 2018 | 30283673 |
| neuropeptide y and orexin immunoreactivity in the sparrow brain coincide with seasonal changes in energy balance and steroids. | the transition between the breeding and nonbreeding states is often marked by a shift in energy balance. despite this well-known shift in energy balance, little work has explored seasonal differences in the orexigenic neuropeptides that regulate food intake in wild animals. here we tested the hypothesis that free-living male song sparrows (melospiza melodia) show seasonal changes in energetic state, circulating steroids, and both neuropeptide y (npy) and orexin (ox) immunoreactivity. nonbreeding ... | 2019 | 30225913 |
| sex-specific additive genetic variances and correlations for fitness in a song sparrow (melospiza melodia) population subject to natural immigration and inbreeding. | quantifying sex-specific additive genetic variance (va ) in fitness, and the cross-sex genetic correlation (ra ), is prerequisite to predicting evolutionary dynamics and the magnitude of sexual conflict. further, quantifying va and ra in underlying fitness components, and genetic consequences of immigration and resulting gene flow, is required to identify mechanisms that maintain va in fitness. however, these key parameters have rarely been estimated in wild populations experiencing natural envi ... | 2018 | 30101430 |
| gut parasite levels are associated with severity of response to immune challenge in a wild songbird. | life history trade-offs have been posited to shape wild animals' immune responses against microparasites (e.g., bacteria, viruses). however, coinfection with gut helminths may bias immune phenotypes away from inflammatory responses and could be another mechanism underlying variation in immune responses. we examined how the magnitude of a common and costly response to microparasites, the acute phase response (apr), varied with helminth coinfection at both the individual and the population levels ... | 2019 | 29999463 |
| individual repeatability and heritability of divorce in a wild population. | understanding micro-evolutionary responses of mating systems to contemporary selection requires estimating sex-specific additive genetic variances and cross-sex genetic covariances in key reproductive strategy traits. one key trait comprises the occurrence of divorce versus mate fidelity across sequential reproductive attempts. if divorce represents an evolving behavioural strategy that responds to selection it must have non-zero individual repeatability and heritability, but quantitative estima ... | 2018 | 29899127 |
| purifying selection in the toll-like receptors of song sparrows melospiza melodia. | variation in immune gene sequences is known to influence resistance to infectious diseases and parasites, and hence survival and mate choice, across animal taxa. toll-like receptors (tlrs) comprise one essential gene family in the vertebrate innate immune system and recognize evolutionarily conserved structures from all major microorganism classes. however, the causes and consequences of tlr variation in passerine birds remain largely unexplored. we examined 7 tlr genes in song sparrows (melospi ... | 2018 | 29893971 |
| husbandry of wild-caught song sparrows (melospiza melodia). | conservation and research efforts occasionally rely upon bringing wild animals into human care to establish breeding programs and to understand their biology. wild-caught birds may have husbandry requirements that differ from captive-reared animals due, in part, to their social development in the wild and potential exposure to novel pathogens. we developed husbandry techniques to minimize stress and monitor health in a population of wild-caught song sparrows (melospiza melodia). we describe encl ... | 2018 | 29740869 |
| the consequences of polyandry for sibship structures, distributions of relationships and relatedness, and potential for inbreeding in a wild population. | the evolutionary benefits of simultaneous polyandry (female multiple mating within a single reproductive event) remain elusive. one potential benefit could arise if polyandry alters sibship structures and consequent relationships and relatedness among females' descendants, thereby intrinsically reducing future inbreeding risk (the indirect inbreeding avoidance hypothesis). however such effects have not been quantified in naturally complex mating systems that also encompass iteroparity, overlappi ... | 2018 | 29693437 |
| exposing migratory sparrows to plasmodium suggests costs of resistance, not necessarily of infection itself. | migratory birds move through multiple habitats and encounter a diverse suite of parasites. this raises concern over migrants' role in transporting infectious disease between breeding and wintering grounds, and along migratory flyways. trade-offs between flight and immune defenses could interfere with infected individuals' migratory timing and success, potentially affecting infection dynamics. however, experimental evidence that parasitic infection affects migratory preparation or timing remains ... | 2018 | 29570956 |
| no evidence of inbreeding depression in sperm performance traits in wild song sparrows. | inbreeding is widely hypothesized to shape mating systems and population persistence, but such effects will depend on which traits show inbreeding depression. population and evolutionary consequences could be substantial if inbreeding decreases sperm performance and hence decreases male fertilization success and female fertility. however, the magnitude of inbreeding depression in sperm performance traits has rarely been estimated in wild populations experiencing natural variation in inbreeding. ... | 2018 | 29435258 |
| immune profiles vary seasonally, but are not significantly related to migration distance or natal dispersal, in a migratory songbird. | a central tenet of ecoimmunology is that an organism's environment shapes its optimal investment in immunity. for example, the benefits of acquired (relatively pathogen specific) versus innate (nonspecific) immune defenses are thought to vary with the risk of encountering familiar versus unfamiliar pathogens. because pathogen communities vary geographically, individuals that travel farther during seasonal migration or natal dispersal are predicted to have higher exposure to novel pathogens, and ... | 2017 | 29356443 |
| territorial aggression in urban and rural song sparrows is correlated with corticosterone, but not testosterone. | urban songbirds of several species more vigorously defend their territories in response to conspecific song playback than do their rural counterparts, but the hormonal basis of this behavioral difference is unclear. it is well established in vertebrates that both testosterone and corticosterone affect the intensity of territoriality. previous studies have found no evidence that initial (i.e., immediately following territorial challenge, but prior to restraint) plasma testosterone accounts for th ... | 2018 | 29166572 |
| birdsong signals individual diversity at the major histocompatibility complex. | the major histocompatibility complex (mhc) plays a key role in vertebrate immunity, and pathogen-mediated selection often favours certain allelic combinations. assessing potential mates' mhc profiles may provide receivers with genetic benefits (identifying mhc-compatible mates and producing optimally diverse offspring) and/or material benefits (identifying optimally diverse mates capable of high parental investment). oscine songbirds learn songs during early life, such that song repertoire conte ... | 2017 | 29118240 |
| fear affects parental care, which predicts juvenile survival and exacerbates the total cost of fear on demography. | fear itself (perceived predation risk) can affect wildlife demography, but the cumulative impact of fear on population dynamics is not well understood. parental care is arguably what most distinguishes birds and mammals from other taxa, yet only one experiment on wildlife has tested fear effects on parental food provisioning and the repercussions this has for the survival of dependent offspring, and only during early-stage care. we tested the effect of fear on late-stage parental care of mobile ... | 2018 | 29030965 |