Search

Urbanization reflects a major form of environmental change impacting wild birds globally. Whereas urban habitats may provide increased availability of water, some food items, and reduced predation levels compared to rural, they can also present novel stressors including increased light at night, ambient noise, and reduced nutrient availability. Urbanization can also alter levels of brood parasitism, with some host species experiencing elevated levels of brood parasitism in urban areas compared to rural areas. Though the demographic and behavioral consequences of urbanization and brood parasitism have received considerable attention, their consequences for cellular‐level processes are less understood. Telomeres provide an opportunity to understand the cellular consequences of different environments as they are a well‐established metric of biological state that can be associated with residual lifespan, disease risk, and behavior, and are known to be sensitive to environmental conditions. Here we examine the relationships between urbanization, brood parasitism, and blood telomere lengths in adult and nestling song sparrows Melospiza melodia. Song sparrows are a North American songbird found in both urban and rural habitats that experience high rates of brood parasitism by brown‐headed cowbirds Molothrus ater in the urban, but not the rural, sites in our study system. Among adults and nestlings from non‐parasitized nests, we found no differences in relative telomere lengths between urban and rural habitats. However, among urban nestlings, the presence of a brood parasite in the nest was associated with significantly shorter relative telomere lengths compared to when a brood parasite was absent. Our results suggest a novel, indirect, impact of urbanization on nestling songbirds through the physiological impacts of brood parasitism. [ABSTRACT FROM AUTHOR]

Aggression is a crucial behavior that impacts access to limited resources in different environmental contexts. Androgens synthesized by the gonads promote aggression during the breeding season. However, aggression can be expressed during the non-breeding season, despite low androgen synthesis by the gonads. The brain can also synthesize steroids ("neurosteroids"), including androgens, which might promote aggression during the non-breeding season. Male song sparrows, Melospiza melodia, are territorial year-round and allow the study of seasonal changes in the steroid modulation of aggression. Here, we quantified steroids following a simulated territorial intrusion (STI) for 10 min in wild adult male song sparrows during the breeding and non-breeding seasons. Using liquid chromatography-tandem mass spectrometry (LC-MS/MS), we examined 11 steroids: pregnenolone, progesterone, corticosterone, dehydroepiandrosterone, androstenedione, testosterone, 5α-dihydrotestosterone, 17β-estradiol, 17α-estradiol, estriol, and estrone. Steroids were measured in blood and 10 microdissected brain regions that regulate social behavior. In both seasons, STI increased corticosterone in the blood and brain. In the breeding season, STI had no rapid effects on androgens or estrogens. Intriguingly, in the non-breeding season, STI increased testosterone and androstenedione in several behaviorally relevant regions, but not in the blood, where androgens remained non-detectable. Also in the non-breeding season, STI increased progesterone in the blood and specific brain regions. Overall, rapid socially modulated changes in brain steroid levels are more prominent during the non-breeding season. Brain steroid levels vary with season and social context in a region-specific manner and suggest a role for neuroandrogens in aggression during the non-breeding season. [ABSTRACT FROM AUTHOR]

Recent research has shown that songbirds that reside at low altitudes can ascend to ∼6000 m above sea level during migratory flight. Since migratory flight is aerobically demanding, whether migratory songbirds exhibit plasticity in breathing to maintain oxygen uptake in low-oxygen environments is unknown. This study investigated whether the hypoxic ventilatory response of sparrows was altered between resident house sparrows (Passer domesticus (Linneaus, 1758)) and migratory song sparrows (Melospiza melodia (A. Wilson, 1810)), and Lincoln's sparrows (Melospiza lincolnii (Audubon, 1834)) or seasonally (long daylight versus short daylight length) within a species. Breathing responses were assessed by stepwise reductions in inspired O2 tension, 21, 16, 12, 9, 7, and 5 kPa during long and short days. Ventilation increased in hypoxia in all species, although song sparrows and Lincoln's sparrows exhibited greater increases in ventilation in severe hypoxia compared to house sparrows. All species became more sensitive to hypoxia during short days compared to long days (increased breathing frequency and total ventilation), with reduced pulmonary oxygen extraction. Although all sparrows had similar ventilatory responses in moderate hypoxia, our findings suggest that migratory sparrows breathe more effectively in severe hypoxia compared to house sparrows, which would be important for maintaining oxygen uptake during migratory flights. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Field Ornithology is the property of Resilience Alliance and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Predators affect the survival of developing young by eating them. More recently, the fear of being eaten has been uncovered as a powerful driver of offspring survival reducing recruited offspring numbers by 53%, but the mechanisms driving these effects are not well understood.We exposed song sparrows to predator or non‐predator playbacks throughout three breeding seasons. We followed offspring as eggs through development and into maturity. We quantified the repercussions of being reared in a fearful environment on body (fat, mass, size) and physiological condition using 12 different measures categorized into six systems (oxygen carrying capacity, energy reserves, immune function, antioxidant protection, oxidative stress/damage, glucocorticoids). We further tracked offspring survival in the nest to maturity and determined which measures of condition significantly predicted survival.We report that fear of predators affected offspring condition at all stages of life, with survival consequences. Predator‐playback offspring hatched from heavier eggs (8%) but quickly lost this advantage and never regained it. Nestlings reared by 'frightened' parents were as heavy and much leaner than non‐predator playback nestlings. This pattern extended throughout development into maturity where offspring reared by frightened parents were up to 31% leaner and 5% lighter. Predator‐playback nestlings also were evidently in poorer physiological condition, having shorter telomeres, while late dependency stage fledglings carried relatively less uric acid and more haptoglobin perhaps indicative of chronic susceptibility to infection.Only body condition (mass and fat) predicted survival during peak mortality periods (nestling and early fledging), with the leanest lightest offspring from the predator‐playback treatment being least likely to survive. Thereafter, mass predicted survival irrespective of playback treatment. Similarly, at this later stage, offspring with less telomere loss and high uric acid levels survived best regardless of playback group.Our findings reveal that fear of predators is a potent form of early life adversity which persistently alters the condition of offspring affecting early stage survival and the 'quality' of the survivors throughout their life. Development is fuelled by food and fear‐induced reductions in parental provisioning at the earliest stages likely instigated these effects, with consequences on the population growth rate. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Song in oscine birds is learned across generations, and aspects of the song-learning process parallel genetic transmission: variation can be introduced into both cultural and genetic traits via copy error, and both types of traits are subject to drift and selective pressure. Similarly to allele frequencies in population genetics, observing frequencies of birdsong features can improve our understanding of cultural transmission and evolution. Uniquely, community science databases of birdsong provide rich spatiotemporal data with untapped potential to evaluate cultural evolution in songbirds. Here we use both community science and field study recordings of chipping sparrows, Spizella passerina , to examine trends across nearly seven decades of song. We found that some syllable types tended to persist in the population for much longer than others. Persistent songs tended to contain more syllables of shorter duration than songs that were observed across fewer years. To draw inferences about the effects of learning biases on chipping sparrow syllables, we constructed a spatially explicit agent-based model of song learning. By comparing our empirical analysis to simulated song distributions using three different song-learning strategies (neutral transmission, conformity bias and directional selection), we suggest that chipping sparrows are unlikely to select tutors neutrally or with a conformity bias and that they learn their songs with a remarkably low copy error rate. • Computational models can complement data from community science. • We model chipping sparrow song learning and compare results to historical recordings. • Chipping sparrows likely select which song they learn and sing as adults. • Their choice of which song they learn may depend on a quality of that song. • Short- and long-lived songs (recorded in 1 vs ≥50 years) have different properties. [ABSTRACT FROM AUTHOR]

• Juvenile male song sparrows are robustly aggressive, like adults. • Androgens and estrogens are low in the blood and brain of juveniles. • Blood and brain progesterone in juveniles increase after an aggressive encounter. • Blood and brain glucocorticoids increase after an aggressive encounter. • Juvenile and adult aggression might use distinct neuroendocrine mechanisms. Aggression is a social behavior that is critical for survival and reproduction. In adults, circulating gonadal hormones, such as androgens, act on neural circuits to modulate aggressive interactions, especially in reproductive contexts. In many species, individuals also demonstrate aggression before reaching gonadal maturation. Adult male song sparrows, Melospiza melodia , breed seasonally but maintain territories year-round. Juvenile (hatch-year) males aggressively compete for territory ownership during their first winter when circulating testosterone is low. Here, we characterized the relationship between the steroid milieu and aggressive behavior in free-living juvenile male song sparrows in winter. We investigated the effect of a 10 min simulated territorial intrusion (STI) on behavior and steroid levels in blood, 10 microdissected brain regions, and four peripheral tissues (liver, pectoral muscle, adrenal glands, and testes). Using liquid chromatography-tandem mass spectrometry (LC-MS/MS), we quantified 12 steroids: pregnenolone, progesterone, corticosterone, 11-dehydrocorticosterone, dehydroepiandrosterone, androstenedione, testosterone, 5α-dihydrotestosterone, 17β-estradiol , 17α-estradiol, estrone, and estriol. We found that juvenile males are robustly aggressive, like adult males. An STI increases progesterone and corticosterone levels in blood and brain and increases 11-dehydrocorticosterone levels in blood only. Pregnenolone, androgens, and estrogens are generally non-detectable and are not affected by an STI. In peripheral tissues, steroid concentrations are very high in the adrenals. These data suggest that adrenal steroids, such as progesterone and corticosterone, might promote juvenile aggression and that juvenile and adult songbirds might rely on distinct neuroendocrine mechanisms to support similar aggressive behaviors. [ABSTRACT FROM AUTHOR]

The fitness of immigrants and their descendants produced within recipient populations fundamentally underpins the genetic and population dynamic consequences of immigration. Immigrants can in principle induce contrasting genetic effects on fitness across generations, reflecting multifaceted additive, dominance, and epistatic effects. Yet full multigenerational and sex-specific fitness effects of regular immigration have not been quantified within naturally structured systems, precluding inference on underlying genetic architectures and population outcomes. We used four decades of song sparrow (Melospiza melodia) life history and pedigree data to quantify fitness of natural immigrants, natives, and their F1, F2, and backcross descendants and test for evidence of nonadditive genetic effects. Values of key fitness components (including adult lifetime reproductive success and zygote survival) of F1 offspring of immigrant-native matings substantially exceeded their parent mean, indicating strong heterosis. Meanwhile, F2 offspring of F1-F1 matings had notably low values, indicating surprisingly strong epistatic breakdown. Furthermore, magnitudes of effects varied among fitness components and differed between female and male descendants. These results demonstrate that strong nonadditive genetic effects on fitness can arise within weakly structured and fragmented populations experiencing frequent natural immigration. Such effects will substantially affect the net degree of effective gene flow and resulting local genetic introgression and adaptation. [ABSTRACT FROM AUTHOR]

Impacts of immigration on micro‐evolution and population dynamics fundamentally depend on net rates and forms of resulting gene flow into recipient populations. Yet, the degrees to which observed rates and sex ratios of physical immigration translate into multi‐generational genetic legacies have not been explicitly quantified in natural meta‐populations, precluding inference on how movements translate into effective gene flow and eco‐evolutionary outcomes. Our analyses of three decades of complete song sparrow (Melospiza melodia) pedigree data show that multi‐generational genetic contributions from regular natural immigrants substantially exceeded those from contemporary natives, consistent with heterosis‐enhanced introgression. However, while contributions from female immigrants exceeded those from female natives by up to three‐fold, male immigrants' lineages typically went locally extinct soon after arriving. Both the overall magnitude, and the degree of female bias, of effective gene flow therefore greatly exceeded those which would be inferred from observed physical arrivals, altering multiple eco‐evolutionary implications of immigration. [ABSTRACT FROM AUTHOR]

Migratory animals may trade-off between investing energy in immune defense versus investing in energy reserves needed for seasonal migration. However, these trade-offs are often masked by other sources of variation and may not be detected through observational field studies of free-living animals. Moreover, observational studies can rarely distinguish the costs of pathogenic infection from those of mounting an immune response. To disentangle such effects, we conducted an immune challenge experiment. We captured song sparrows (Melospiza melodia) and white-throated sparrows (Zonotrichia albicollis) in autumn migratory condition, challenged the sparrows with non-infectious antigens that induce an acute-phase immune response, then monitored body composition and migratory restlessness behavior. For both species, body mass was higher the day after exposure to keyhole limpet hemocyanin (KLH) compared to controls. White-throated sparrows, but not song sparrows, increased lean mass 1 week after exposure to lipopolysaccharide (LPS), suggesting that effects of immune upregulation on body composition may be long-lasting and specific to certain combinations of hosts and antigens. White-throated sparrows exposed to KLH increased nocturnal migratory restlessness (Zugunruhe) for the week following exposure. These findings suggest that short-term activation of the acute immune response does not constrain migratory physiology in these songbirds. [ABSTRACT FROM AUTHOR]

The inheritance of structural characteristics and individual note parameters is often studied in oscine passerines. However, other song features, such as the temporal characteristics of song, are less well studied. Inheritance of these features could be influenced by a range of factors, including social inheritance, mechanical constraints, genetic relatedness and the developmental environment. Using archived song data, we examined patterns of inheritance of temporal song features, relating to song duration, song tempo and internote intervals, in a laboratory population of Java sparrows, Padda oryzivora , some of which had been cross fostered. Overall, we found strong evidence for cultural inheritance of temporal song features, that is, temporal song features were learned from the social father. We found that song duration was, at most, weakly socially inherited and constrained by a correlation between song tempo and number of notes. Internote gap durations were also influenced by other song features, in particular the duration of the preceding and following notes, although social learning was still apparent when controlling for these features. Across all measures, we found no evidence that temporal song features were affected by genetic relatedness or the developmental environment. Our findings, and those in other species, suggest that temporal song features are likely to be inherited through a combination of the learning of song structure and spectral structure of notes, and specific learning of temporal song features during development. • Many temporal features of Java sparrow song are socially inherited. • Gap durations are affected by a range of song characteristics. • No evidence that genetics or the developmental environment affect temporal features. • Social learning may drive song divergence and affect gene flow between populations. [ABSTRACT FROM AUTHOR]

In many taxa, melanin-based coloration is a signal of dominance or fighting ability and is associated with concentrations of hormones that may mediate aggressive behavior. Previous studies found that experimental manipulation of melanin-based signals can result in manipulated individuals receiving more social challenges in some but not all species. These differences could arise from mismatches between the signal, behavior, and hormone concentrations. In the present study, we experimentally manipulated the chest spotting of urban and rural male song sparrows (Melospiza melodia) following an assessment of their territorial aggression and initial concentrations of corticosterone and testosterone and then assessed their behavior and hormone concentrations 2 weeks later. We found that males generally displayed less territorial aggression in the second trial, consistent with our previous findings. Males in the enlarged treatment decreased aggression to a greater degree than those in the reduced treatment. The effect of the plumage manipulation was similar across the rural and urban habitats. Despite the changes in behavior we detected, we found no effects of the manipulation on concentrations of testosterone or corticosterone. Our results show that melanin-based spotting in male song sparrows is a signal of territorial aggression but the physiological mechanisms that mediate the relationships between chest spotting and behavior remain to be identified. Significance statement: Many bird species use their plumage to signal their dominance status, fighting ability, or motivation during interactions with other individuals to resolve conflicts without a fight. Here, we asked whether chest spotting is a signal in territorial interactions among male song sparrows. We experimentally increased or reduced the extent of spotting in males and measured the change in their aggression. We found that reduced-spotting males showed a more moderate seasonal decrease of aggression compared to males with enlarged spotting reduced aggression, possibly because the former experienced more intrusions later on in the breeding season while the latter experienced fewer intrusions. These results are consistent with chest spotting size in song sparrows functioning as a signal of territory holding potential of the bearer. [ABSTRACT FROM AUTHOR]

Spatial variation in the environment can affect population fitness and individual phenotype by facilitating natural selection and local adaptation, and thereby enhance the diversity and adaptive capacity and persistence of species at regional to continental scales. The song sparrow subspecies complex endemic to the San Francisco Bay region, which has received over a century of close study, presents an opportunity to evaluate the adaptive potential of distinct subspecies faced with habitat loss, population decline, and threats of future environmental change. We used whole-genome sequences from 39 individuals representing five morphologically distinct song sparrow subspecies to evaluate the role of neutral and adaptive evolutionary processes in driving divergence within physiologically challenging habitats across multiple environmental clines. We found that natural selection for traits explained by ecological variables, including temperature and salinity, are drivers of adaptive genetic variation in these song sparrows. Differentiation was highest for candidate loci under selection (compared to neutral markers), as predicted if local ecological processes are at least partially responsible for the rapid radiation of these subspecies. Our findings inform management aimed at conserving and prioritizing population-level diversity in species displaying local adaptation and inhabiting a diverse range of environments. [ABSTRACT FROM AUTHOR]

Ecogeographic rules denote spatial patterns in phenotype and environment that may reflect local adaptation as well as a species' capacity to adapt to change. To identify genes underlying Bergmann's Rule, which posits that spatial correlations of body mass and temperature reflect natural selection and local adaptation in endotherms, we compare 79 genomes from nine song sparrow (Melospiza melodia) subspecies that vary ~300% in body mass (17 − 50 g). Comparing large- and smaller-bodied subspecies revealed 9 candidate genes in three genomic regions associated with body mass. Further comparisons to the five smallest subspecies endemic to California revealed eight SNPs within four of the candidate genes (GARNL3, RALGPS1, ANGPTL2, and COL15A1) associated with body mass and varying as predicted by Bergmann's Rule. Our results support the hypothesis that co-variation in environment, body mass and genotype reflect the influence of natural selection on local adaptation and a capacity for contemporary evolution in this diverse species. Ecogeographic rules link spatial patterns in phenotype and environment, potentially reflecting adaptation. This study identifies nine genes associated with body mass variation in song sparrow populations, supporting Bergmann's Rule and highlighting the role of natural selection in local adaptation. [ABSTRACT FROM AUTHOR]

On 29 October 2022, a first-year male Common Yellowthroat was found at Diga della Pèpa, Magadino (canton of Ticino). The bird was observed regularly until 13 December 2022, the date of its last observation in the area. This is the first record of this species in Switzerland, as well as the first Parulidae and only the second record of a North American songbird in Switzerland after a Song Sparrow Melospiza melodia was found in Turtmann-Unterems (canton of Valais) on 1 May 2010. This is a notable observation, since most North American passerines in Europe are recorded along the coast and on islands of the Atlantic and the North Sea. Of the 46 accepted records of Common Yellowthroats in Europe, this is the first in the inland of the continent. [ABSTRACT FROM AUTHOR]

Song-type sharing is common within populations of songbirds and often varies among individuals depending on the geographical distance between territories due to differences in song-learning strategies and natal dispersal behavior. Comparing spatial patterns of song-type sharing may allow us to infer song-learning strategies and dispersal behavior for any given species or population. Song learning and dispersal are unknown for Peucaea aestivalis (Bachman's Sparrow), an endemic songbird of the southeastern United States that is declining throughout much of its range and is considered to be near threatened. Our objective was to compare the number of song-types shared among male Bachman's Sparrows to make inferences about song development and dispersal. From 2016 to 2019, we recorded male sparrow songs in 3 different sites in South Florida, and determined song-type repertoires and song-type sharing among males within and between sites by visually comparing individual song spectrograms. Repertoire size varied among individuals and sites. Within sites, sharing did not decline with distance; between sites, sharing correlated with geographic distance between males, with song-type sharing greater at closer distances and lower at farther distances. These data suggest that Bachman's Sparrows may have an extended song-learning period and typically attempt short-distance dispersals from natal areas but disperse farther if suitable and vacant territories are not available nearby. [ABSTRACT FROM AUTHOR]

A hallmark of expert object recognition is rapid and accurate subordinate-category recognition of visually homogenous objects. However, the perceptual strategies by which expert recognition is achieved is less known. The current study investigated whether visual expertise changes observers' perceptual field (e.g., their ability to use information away from fixation for recognition) for objects in their domain of expertise, using a gaze-contingent eye-tracking paradigm. In the current study, bird experts and novices were presented with two bird images sequentially, and their task was to determine whether the two images were of the same species (e.g., two different song sparrows) or different species (e.g., song sparrow and chipping sparrow). The first study bird image was presented in full view. The second test bird image was presented fully visible (full-view), restricted to a circular window centered on gaze position (central-view), or restricted to image regions beyond a circular mask centered on gaze position (peripheral-view). While experts and novices did not differ in their eye-movement behavior, experts' performance on the discrimination task for the fastest responses was less impaired than novices in the peripheral-view condition. Thus, the experts used peripheral information to a greater extent than novices, indicating that the experts have a wider perceptual field to support their speeded subordinate recognition. [ABSTRACT FROM AUTHOR]

Haemosporidian parasites are significant global drivers of avian disease and infections are affected by complex ecological and biological interactions. We quantified variation in haemosporidian infection prevalence of Plasmodium, Haemoproteus, and Leucocytozoon in 311 Song Sparrows (Melospiza melodia) from 2 breeding populations across years, seasons, age classes, and sexes, finding significant differences in infection prevalence across years, seasons, and sites, as well as sex differences in Leucocytozoon infection prevalence. We also found that birds were more likely to be infected with Plasmodium than Leucocytozoon and coinfections were more likely than expected. Many avian haemosporidian studies use data collected over a short period of time at one location, and few studies investigate multi-year infection dynamics across populations. However, such long-term studies are important because ecological factors can affect the distribution and prevalence of vector-borne pathogens like malaria. Because biological factors can also affect the likelihood of exposure to vector-borne pathogens, it is also important to determine how host traits influence infection dynamics. Our results demonstrate that the prevalence and composition of avian haemosporidian infections can be highly variable, making sampling regimes a key consideration when drawing conclusions from study results. To better understand the fitness consequences of haemosporidian infection in avian hosts, future work should take ecological and biological variation into account when evaluating the effects of infection on aspects of condition and quality, reproductive success, and survival. [ABSTRACT FROM AUTHOR]

Song type matching has been hypothesized to be a graded signal of aggression; however, it is often the case that variation in matching behavior is unrelated to variation in aggressiveness. An alternative view is that whether an individual matches a song is determined mainly by syntactic rules governing how songs are sequenced. In song sparrows (Melospiza melodia), two such rules are the cycling rule, which directs that a bird cycles through its song types in close to the minimum number of bouts, and the bout length rule, which directs that a long bout of a song type is followed by a long interval before that song type is sung again. The effect of these rules on matching is confirmed here for a population of eastern song sparrows. Territorial males were challenged at the end of a recording session with playback of one of their own song types. Logistic regression showed that the probability of matching the playback song type increased with the length of the interval since the subject had last sung that song type, as predicted by the cycling rule. The probability of matching decreased as prior bout length increased, as predicted by the bout length rule. In a multivariate logistic regression, interval length and prior bout length were both associated with matching and together correctly predicted matching in 81.3% of cases. The results support the syntactic constraints hypothesis, which proposes that matching is a non-signaling by-product of internal rules governing the ordering of song type sequences. Significance statement: Vocal matching has attracted widespread interest in large part because it seems an effective method of directing an aggressive message at a particular recipient. Here, we show that in an eastern population of song sparrows, decisions on whether to match another bird are largely determined by internal rules of syntax governing how a singer sequences its song types, rather than by variation in aggressiveness or other individual traits. These results support the view that vocal matching is an incidental byproduct of internal mechanisms controlling the ordering of vocalization types and so is not a signal at all. This hypothesis may be broadly applicable to vocal matching in other species. [ABSTRACT FROM AUTHOR]

Although the impacts of intensive agriculture on biodiversity and strategies for mitigating these effects have been widely described, small-scale, diversified farms and the opportunities they present for bird conservation have been less thoroughly examined. This omission is potentially significant, because this form of agriculture represents a growing sector of the industry in the populous northeastern USA, and the diverse habitats on these farms contrast with larger, structurally homogeneous intensive agriculture. To evaluate bird-habitat associations and conservation opportunities for supporting species of conservation concern on these small, diversified farms, we conducted avian point count and vegetation surveys across 23 farms in western Massachusetts during the summers of 2017 and 2018. We used Poissonbinomial mixture models and canonical correspondence analysis to assess the effects of a suite of microhabitat-, field- and landscape-scale (1 km buffer around the field) variables on the abundance of bird species. Our results confirmed that shrubland birds, a group of species of elevated conservation concern, accounted for 52% of the total observations, including song sparrow (Melospiza melodia), gray catbird (Dumatella carolinensis), common yellowthroat (Geothlypis trichas) and American goldfinch (Spinus tristis). Species-habitat relationships were diverse; however, smaller field sizes, and increased cover of tall, dense, woody or non-productive vegetation types were associated with higher abundance of shrubland species as well as lower abundance of crop pests such as European starling (Sturnus vulgaris) and house sparrow (Passer domesticus). These findings support the hypothesis that small, diversified farms are supporting birds of high conservation concern, and we provide species-specific guidelines for farmers interested in conserving birds on their land. [ABSTRACT FROM AUTHOR]

The song of the Seaside Sparrow (Ammospiza maritima) is a 2-phrase song, with a complex introduction and a terminal buzz, that has previously been shown to exhibit some interindividual and between-population variation. Comparatively little is known about geographic variation in Seaside Sparrow song, or if song structure corresponds to either subspecies or coastal lineages (Atlantic vs. Gulf of Mexico). We collected recordings from all recognized subspecies throughout the species’ range to ask whether variation in Seaside Sparrow song corresponds with subspecies or coastal lineage designation. Coastal lineage groups of Seaside Sparrow varied significantly with respect to a number of frequency and temporal characters. Most notably, frequencies of the introductory syllable within the first phrase were higher for the Gulf coast lineage whereas frequency measures for the terminal syllable within the first phrase were lower. Additionally, the number of syllables in the first phrase was greater within the Gulf coast group. A multiple logistic regression analysis using 6 song measures classified coastal lineage groups with 96% accuracy but failed to differentiate 7 subspecies for which we had sufficient data. [ABSTRACT FROM AUTHOR]

Classification tasks are some of the most widely known machine learning applications. Computers can classify images, sounds, and patterns with high accuracy, given enough training data, time, and computational resources. After training, computers can perform identification tasks faster than humans and often with less error. In contrast, humans are well equipped for anomaly identification and can adapt to new information quickly and effectively. Thus we introduce DialectDecoder, a tool that uses human intelligence and machine learning to classify different dialects of White-crowned Sparrow songs, relying on both the human and the computer for different parts of the classification process. DialectDecoder is an example of humans and computers working together to detect and classify anomalies. After preprocessing the data and training the classifiers with the built-in tools, each new song is fed to the network where the computer classifies the song as a specific dialect or gives the song conflicting labels which, with the song, are sent to the expert human for classification. The human expert can label all songs with conflicting labels and append them to the training set, which provides the computer with updated information to retrain on. We performed three different tests that illustrate the applicability of human-machine teaming and demonstrate the ability of DialectDecoder, paired with an expert human, to classify different dialects of White-crowned Sparrow songs. Then, we discuss extensions of DialectDecoder and its applicability to other human-machine teaming tasks that leverage the distinct strengths contributed by each half of the partnership to improve overall performance. • Human-machine teaming improves bird song classification. • Classification algorithms can be improved with human input. • Combining multiple types of machine learning algorithms leads to better classification. • Using multiple data streams provides better bird song classification. [ABSTRACT FROM AUTHOR]

Symbiotic microbes can affect host behavior and fitness. Gut microbiota have received the most study, with less attention to other important microbial communities like those of scent-producing glands such as mammalian anal glands and the avian uropygial gland. However, mounting evidence suggests that microbes inhabiting scent-producing glands play an important role in animal behavior by contributing to variation in chemical signals. Free-living and captive conditions typically differ in social environment, food diversity and availability, disease exposure, and other factors—all of which can translate into differences in gut microbiota. However, whether extrinsic factors such as captivity alter microbial communities in scent glands remains an open question. We compared the uropygial gland microbiota of free-living and captive song sparrows (Melospiza melodia) and tested for an effect of dietary manipulations on the gland microbiota of captive birds. As predicted, the uropygial gland microbiota was significantly different between free-living and captive birds. Surprisingly, microbial diversity was higher in captive than free-living birds, and we found no effect of dietary treatments on captive bird microbiota. Identifying the specific factors responsible for microbial differences among groups and determining whether changes in symbiotic microbiota alter behavior and fitness are important next steps in this field. [ABSTRACT FROM AUTHOR]

Although the effects of learning on song structure have been extensively studied in songbirds, little attention has been given to the learning of syntax at the level of song sequences. Here we investigate song syntax learning in two cohorts of hand-reared song sparrows, Melospiza melodia : an isolate group, consisting of four males raised with no exposure to external song models, and a trained group, consisting of 17 males exposed to recorded song sequences during the sensitive period for song learning. The isolate males followed three syntactical rules previously described for field-recorded song sparrows: (1) they produced their song type repertoires with eventual variety, repeating a song type multiple times before switching to another; (2) they cycled through their repertoires using close to the minimum number of bouts; and (3) they showed consistent preferences for singing certain of their song types more than others. The trained males were tutored with sequences with exaggerated eventual variety and cycling patterns and no usage preferences, but their syntax was little affected by any of these training features. One syntactical pattern that was affected by external experience was the rule that long bouts of a song type are followed by long recurrence intervals before that type is produced again. Isolate males showed no bout length/recurrence interval correlations while trained males showed reduced correlations relative to field-recorded males, implicating learning in the development of the normal pattern. Other songbird species have been found to preferentially use song type transitions as adults that they were tutored with as juveniles, but the trained song sparrows in this study showed no evidence of such effects. • We examined the development of between-song syntax in song sparrows. • Singing with eventual variety is one syntactical pattern little affected by learning. • A second is the tendency to cycle efficiently through the song type repertoire. • Song sparrows do not learn first-order transition preferences from tutor sequences. • Usage learning is thus less prevalent than vocal production learning in this species. [ABSTRACT FROM AUTHOR]

The costs and benefits of breeding behaviors are influenced by environmental conditions, and habitat variation can shift the degree to which behaviors are expressed. Novel urban habitats have been shown to differ significantly in disturbances such as noise, light at night, and human presence, as well as resource availability, compared to rural habitats. Perhaps because of these environmental differences, urban males of several species are consistently more aggressive than rural males, raising the hypothesis that greater territorial aggression is beneficial in urban habitats. Though often ignored, female songbirds of many species also perform aggressive territorial behaviors toward conspecifics during the breeding season. For socially monogamous songbirds, this aggression functions to ensure partner fidelity and secure resources for reproduction. Studies of the effects of urbanization on songbird behavior have yet to determine if urban females also express greater territorial aggression. Importantly, energetically demanding behaviors such as territoriality and parental care should constrain one another, leading to behavioral trade-offs during the breeding season. Though territorial aggression and parental care are inversely related in males of several species of songbird, this relationship is understudied in female songbirds, particularly those facing environmental change, such as urbanization. In this study, we compared aggressive signaling and a measure of parental care (maternal nest visitation rates) between female song sparrows (Melospiza melodia), living in urban and rural habitats. We hypothesized that female aggressive signaling would be higher in urban environments compared to rural, and negatively correlated with maternal visitation rates. We found that urban females, like males, expressed increased aggressive signaling compared to rural. However, female aggressive signaling was not related to our measure of maternal care, suggesting females aren't facing a trade-off between these two behaviors. Collectively, our results are consistent with the hypothesis that urban habitats promote territorial aggression in female song sparrows. As urbanization continues to spread, understanding the behavioral changes animals employ in urban environments requires studying individuals of different sexes and age classes, and will help us understand how some species are able to cope with human-induced rapid environmental change. [ABSTRACT FROM AUTHOR]

This article, published in the Florida Field Naturalist, explores the process of song learning and development in juvenile Bachman's Sparrows. The study compares the development of song production in different avian species and emphasizes the importance of studying a wide range of species to understand variation in early song development. The researchers conducted field observations and recordings of juvenile Bachman's Sparrows in Florida, documenting their songs and categorizing them into different stages of development. The study highlights the need for further research on song learning in species with larger repertoires, like the Bachman's Sparrow, and the potential impact of declining populations on song learning and conservation efforts. [Extracted from the article]

Anthropogenic land use, including urbanization, has caused population declines across diverse taxa including arthropods and songbirds. Declines in one taxa can impact other groups based on its role in a community. In particular, declines in lower trophic level taxa, such as arthropods, could have negative impacts on higher trophic level species. Here, we examined how urban arthropod communities compare to rural ones and how these differences may impact song sparrow (Melospiza melodia) nestlings living in urban and rural habitats. We quantified differences in the abundance, biomass, and diversity of arthropod communities between replicate urban and rural sites. At the same sites, we also compared the stomach contents of nestlings because song sparrows rely upon arthropod prey during development. We found that the arthropod community in urban habitats had lower average abundance, average biomass, and Simpson's diversity compared to rural habitats. The arthropod communities also significantly differed in the relative abundance of some higher trophic level taxa, such as spiders. However, we found no difference in the total stomach content mass, nor the mass of invertebrate food items in the stomachs of urban and rural nestlings. Thus, though urban habitats had lower availability of arthropods, possibly driven by the simplification of urban habitats, there was no evidence of a negative impact on the quantity of food provided to urban song sparrow nestlings., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Predicting the geographic range of species and their response to climatic variation and change are entwined goals in conservation and evolutionary ecology. Species distribution models (SDMs) are foundational in this effort and used to visualize the geographic range of species as the spatial representation of its realized niche. SDMs are also used to forecast range shifts under climate change, but often in the absence of empirical evidence that climate limits population growth. We explored the influence of climate on demography, seasonal migration, and the extent of the geographic range in song sparrows (Melospiza melodia), a species thought to display marked local adaptation to regional climate. To do so, we developed SDMs to predict the demographic and climate niches of migratory and resident song sparrows across our study area in western North America from California to Alaska, using 48 years of demographic data from a focal population in British Columbia and 1.2 million continental-scale citizen science observations. Spatial agreement of our demographic and climate niche models in the region of our focal population was strong (76%), supporting the hypothesis that demographic performance and the occurrence of seasonal migration varied predictably with climatic conditions. In contrast, agreement at the northern (58%) and southern (40%) extents of our study area was lower, as expected if the factors limiting population growth vary regionally. Our results support the hypothesis that local climate drives spatial variation in the occurrence of seasonal migration in song sparrows by limiting the fitness of year-round residents, and suggest that climate warming has favored range expansions and facilitated an upward shift in elevational range song sparrows that forgo seasonal migration. Our work highlights the potential role of seasonal migration in climate adaptation and limits on the reliability of climate niche models not validated with demographic data. [ABSTRACT FROM AUTHOR]

Premise: Invasive plants in wetlands are often ecosystem engineers, mediating changes in ecosystem functions like trophic support. We documented the impacts of Lepidium latifolium, an invasive plant, on the food web of omnivorous birds (Suisun song sparrows, Melospiza melodia maxillaris) in a tidal wetland of northern California, USA. Methods: We used analysis of natural abundance stable isotopes of 13C and 15N in song sparrow blood, invertebrate food sources, L. latifolium seeds, and other marsh plant seeds to inform Bayesian, concentration‐dependent mixing models that predicted average song sparrow diets. Results: Season and plant phenology influenced food source incorporation and isotopic signatures. Song sparrows showed higher isotopic variability in the summer. The observed changes in song sparrow diets were driven by altered invertebrate communities related to seasonal L. latifolium presence and by shifts from seeds to consumption of invertebrate food sources during the breeding season in the spring and summer. Discussion: This study used stable isotope tools and modeling to demonstrate two mechanisms of isotopic influence by L. latifolium on omnivorous song sparrows. This study can inform site‐ and species‐specific management strategies by demonstrating how changes to the plant community can impact entire trophic systems. [ABSTRACT FROM AUTHOR]

Several studies have examined how grassland birds use reclaimed surface mines during the breeding season, but few studies have documented how these birds use these areas during the winter and early spring months. Using point counts, birds occupying a reclaimed surface-mine site in southeastern Ohio were surveyed from late December 2020 to April 2021. The primary objective was to document bird abundance and species richness across a temporal gradient spanning from late December 2020 through April 2021. Additionally, bird species composition was examined in habitat patches dominated by coolseason plants and in a single warm-season plot dominated by switchgrass (Panicum virgatum). A total of 1,452 bird sightings were made consisting of 40 species in 7 orders. Songbirds (order Passeriformes) comprised 60% of all sightings, and most of these (53%) were Red-winged Blackbirds (Agelaius phoeniceus), Eastern Meadowlarks (Sturnella magna), and Song Sparrows (Melospiza melodia). Thirty-nine species were observed on cool-season sites versus 13 species in the switchgrass plot. Species including returning Eastern Meadowlarks, Henslow's Sparrows (Centronyx henslowii), and Field Sparrows (Spizella pusilla) were common on the cool-season plots, but uncommon or absent in the switchgrass plot. Conversely, the switchgrass plot had more wintering American Tree Sparrows (Spizelloides arborea) and returning Swamp Sparrows (Melospiza georgiana). Return rates of long-distance migratory species fell within the time frames for these species as obtained from previous studies in this region. The diverse habitat structure of the cool-season portions of this study site attracted some winter species, including birds of prey, as well as several returning migratory species. [ABSTRACT FROM AUTHOR]

Adaptation to local environments is common in widespread species and the basis of ecological speciation. The song sparrow (Melospiza melodia) is a widespread, polytypic passerine that occurs in shrubland habitats throughout North America. We examined the population structure of two parapatric subspecies that inhabit different environments: the Atlantic song sparrow (M. m. atlantica), a coastal specialist, and the eastern song sparrow (M. m. melodia), a shrubland generalist. These populations lacked clear mitochondrial population structure, yet coastal birds formed a distinct nuclear genetic cluster. We found weak overall genomic differentiation between these subspecies, suggesting either recent divergence, extensive gene flow, or a combination thereof. There was a steep genetic cline at the transition to coastal habitats, consistent with isolation by environment, not isolation by distance. A phenotype under divergent selection, bill size, varied with the amount of coastal ancestry in transitional areas, but larger bill size was maintained in coastal habitats regardless of ancestry, further supporting a role for selection in the maintenance of these subspecies. Demographic modeling suggested a divergence history of limited gene flow followed by secondary contact, which has emerged as a common theme in adaptive divergence across taxa. [ABSTRACT FROM AUTHOR]

Food acquisition is critical for individual fitness. Recent work has highlighted the importance of behavioral traits, such as boldness, for explaining variation in foraging abilities within populations. Greater flexibility in these behavioral traits might help populations persist in the face of environmental change; this may be particularly important for small populations that are more susceptible to local extirpation. We performed a winter-feeding experiment in an extensively studied island population of Song Sparrows (Melospiza melodia) to examine if intrinsic factors (age, sex, and inbreeding) explain variation in behavioral traits (neophobia, boldness toward predators, boldness toward competitors, and aggression) and how behavioral traits influence the probability of local survival for adults and of no dispersal and survival for juveniles. Our results showed that adults were less neophobic and bolder toward competitors than juveniles. This suggests that juvenile Song Sparrows might be more vulnerable to environmental changes than adults and may help explain why juvenile survival has been more strongly impacted by a new competitor on the island. Females were less neophobic than males, indicating that the sexes vary in their behaviors associated with resource acquisition, potentially due to constraints associated with reproduction in females. We found that the individual inbreeding coefficient did not appear to influence any of the behavioral traits examined here. Lastly, more neophobic adults were found to be more likely to survive to hold a territory the following breeding season, demonstrating the consequences of behavior on future fitness. These findings highlight that behavioral traits impact resource acquisition and fitness, and, thus, variation in these behaviors may play a critical role in understanding and predicting how populations respond to environmental change. La adquisición de alimento es crítica para la sobrevivencia individual. Trabajos recientes han destacado la importancia de características conductuales, como la osadía, para explicar la variación en capacidades de forrajeo al interior de poblaciones. Una mayor flexibilidad en características conductuales podría ayudar a las poblaciones a persistir de cara al cambio ambiental y esto podría ser particularmente importante para poblaciones pequeñas que son más susceptibles a extinciones locales. Llevamos a cabo un experimento de alimentación invernal en una población del gorrión Melospiza melodia que ha sido extensamente estudiada para examinar si factores intrínsecos (edad, sexo y endogamia) explican la variación en las características conductuales (neofobia, osadía ante depredadores, osadía ante competidores y agresión) y cómo las características conductuales influencian la probabilidad de sobrevivencia local para los adultos, y la nodispersión y sobrevivencia para juveniles. Nuestros resultados muestran que los adultos fueron menos neofóbicos y más osados hacia competidores que los juveniles. Esto sugiere que los gorriones juveniles podrían ser más vulnerables a cambios ambientales que los adultos y esto podría ayudar a explicar por qué la sobrevivencia de los juveniles ha estado más fuertemente impactada ante un nuevo competidor en la isla. Las hembras fueron menos neofóbicas que los machos, indicando que los sexos varían en comportamientos asociados con adquisición de recursos, potencialmente debido a limitaciones asociadas con la reproducción en las hembras. Encontramos que el coeficiente de endogamia individual no parece influenciar ninguna de las características conductuales que examinamos aquí. Finalmente, los adultos más neofóbicos fueron más proclives a sobrevivir y asegurar un territorio en la siguiente temporada reproductiva, demostrando las consecuencias del comportamiento en la sobrevivencia futura. Estos hallazgos destacan que las características conductuales impactan la adquisición de recursos y, por ello, la variación en estas conductas podría jugar un papel crítico en nuestro entendimiento y capacidad de predecir cómo responden las poblaciones al cambio ambiental. Palabras clave: agresión, edad, neofobia, nivel de endogamia, osadía, sexo. [ABSTRACT FROM AUTHOR]

Social communication often involves vocal learning, whereby young animals learn their vocalizations early in life by imitating the sounds of adults. In animals that learn their vocalizations, it is common to find patterns of geographical variation known as 'vocal dialects', acoustic features shared within a cluster of animals that differ from the vocalizations of animals in nearby clusters. Dialects may form when animals learn their vocalizations early in life and then disperse short distances, or when they modify their vocalizations to match local vocal patterns after dispersal. Dialects are typically studied at a regional or continental scale, but they may also persist at smaller scales in so-called 'microgeographical song dialects' or 'microdialects'. Microdialects have received little research attention. In this study, we investigate microdialects and dispersal distance in song-learning Savannah sparrows, Passerculus sandwichensis , through a 4-year study of birds living on three islands in the Bay of Fundy, Canada. Our analyses yield evidence of microgeographical variation: birds showed higher acoustic similarity to their neighbours than to faraway individuals in the same population. When we classified songs on the basis of their highly variable middle sections, we found that particular song types formed spatial clusters of similar-sounding individuals. Therefore, acoustic variation in Savannah sparrow song appears to show dialects across small geographical distances. In an analysis of dispersal from natal sites to breeding sites, we found a median distance of 189 m, consistent with previous findings. Our results suggest that limited dispersal distances, combined with the social processes of vocal learning (overproduction and selective attrition), likely contribute to the presence of microdialects. • Vocal dialects are well known at broad scales, but rarely studied at small scales. • We studied microdialects in Savannah sparrows over 4 years on three islands. • The songs of males were more similar to those of neighbours than to distant birds. • Savannah sparrows dispersed short distances from their natal nest. • Thus, local song learning and limited dispersal likely give rise to microdialects. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Field Ornithology is the property of Resilience Alliance and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article presents the discussion on temperate-zone passerines undergoing a preformative molt during the first cycle. Topics include researchers capturing and band wild birds distinguishing individuals in the first plumage cycle; and primary coverts uniformly dull brown, matching the apparently older flight feathers ruling out the possibility of a suspended pre-basic molt.