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592 results for “songbirds”
Data from: Activity and migratory flights of individual free-flying songbirds throughout the annual cycle: method and first case study
We describe a method and device (< 1.2 g) for recording, processing and storing data about activity and location of individuals of free-living songbirds throughout the annual cycle. Activity level was determined every five minutes from five 100 ms samples of accelerometer data with 5 s between the sampling events. Activity levels were stored on an hourly basis throughout the annual cycle, allowing periods of resting/sleep, continuous flight and intermediate activity (foraging, breeding) to be distinguished. Measurements from a light sensor were stored from preprogrammed key stationary periods during the year to provide control information about geographic location. Successful results, including annual actogram, were obtained for a red-backed shrike Lanius collurio carrying out its annual loop migration between northern Europe and southern Africa. The shrike completed its annual migration by performing > 66 (max. 73) nocturnal migratory flights (29 flights in autumn and > 37, max. 44, in spring) adding up to a total of > 434 (max. 495) flight hours. Migratory flights lasted on average 6.6 h with maximum 15.9 h. These flights were aggregated into eight travel episodes (periods of 4–11 nights when flights took place on the majority of nights). Daytime resting levels were much higher during the winter period compared to breeding and final part of spring migration. Daytime resting showed peaks during days between successive nocturnal flights across Sahara, continental Africa and the Arabian Peninsula, indicating that the bird was mostly sleeping between these long migratory flights. Annual activity and flight data for free-living songbirds will open up many new research possibilities. Main topics that can be addressed are e.g. migratory flight performance (total flight investment, numbers and characteristics of flights), timing of stationary periods, activity patterns (resting/sleep, activity level) in different phases of the annual cycle and variability in the annual activity patterns between and within individuals.
Data from: Artificial light at night does not affect telomere shortening in a developing free-living songbird: a field experiment
Artificial light at night (ALAN) is an increasingly pervasive anthropogenic disturbance factor. ALAN can seriously disrupt physiological systems that follow circadian rhythms, and may be particularly influential early in life, when developmental trajectories are sensitive to stressful conditions. Using great tits (Parus major) as a model species, we experimentally examined how ALAN affects physiological stress in developing nestlings. We used a repeated-measure design to assess effects of ALAN on telomere shortening, body mass, tarsus length and body condition. Telomeres are repetitive nucleotide sequences that protect chromosomes from damage and malfunction. Early life telomere shortening can be accelerated by environmental stressors, and has been linked to later-life declines in survival and reproduction. We also assayed nitric oxide, as an additional metric of physiological stress, and determined fledging success. Change in body condition between day 8 and 15 differed according to treatment. Nestlings exposed to ALAN displayed a trend towards a decline in condition, whereas control nestlings displayed a trend towards increased condition. This pattern was driven by a greater increase in tarsus length relative to mass in nestlings exposed to ALAN. Nestlings in poorer condition and nestlings that were smaller than their nest mates had shorter telomeres. However, exposure to ALAN was unrelated to telomere shortening, and also had no effect on nitric oxide concentrations or fledging success. Thus, exposure to ALAN may not have led to sufficient stress to induce telomere shortening. Indeed, plasticity in other physiological systems could allow nestlings to maintain telomere length despite moderate stress. Alternatively, the cascade of physiological and behavioral responses associated with light exposure may have no net effect on telomere dynamics.
Data from: A conceptual framework for clutch size evolution in songbirds
Causes of evolved differences in clutch size among songbird species remain debated. I propose a new conceptual framework that integrates aspects of traditional life history theory, while including novel elements, to explain evolution of clutch size among songbirds. I review evidence that selection by nest predation on length of time that offspring develop in the nest creates a gradient in offspring characteristics at nest-leaving (fledging), including flight mobility, spatial dispersion, and self-feeding rate. I postulate that this gradient has consequences for offspring mortality rates and parental energy expenditure per offspring. These consequences then determine how reproductive effort is partitioned among offspring, while reproductive effort evolves from age-specific mortality effects. Using data from a long-term site in Arizona, as well as from the literature, I provide support for hypothesized relationships. Nestling development period consistently explains fledgling mortality, energy expenditure per offspring, and clutch size while accounting for reproductive effort (i.e., total energy expenditure) to thereby support the framework. Tests in this paper are not definitive, but they document previously unrecognized relationships and address diverse traits (developmental strategies, parental care strategies, energy requirements per offspring, evolution of reproductive effort, clutch size) that justify further investigations of hypotheses proposed here.
Data from: A range-wide domino effect and resetting of the annual cycle in a migratory songbird
Latitudinal differences in timing of breeding are well documented but how such differences carry over to influence timing of events in the annual cycle of migratory birds is not well understood. We examined geographic variation in timing of events throughout the year using light-level geolocator tracking data from 133 migratory tree swallows (Tachycineta bicolor) originating from 12 North American breeding populations. A swallow's breeding latitude influenced timing of breeding, which then carried over to affect breeding ground departure. This resulted in subsequent effects on the arrival and departure schedules at fall stopover locations and timing of arrival at non-breeding locations. This "domino effect" between timing events was no longer apparent by the time individuals departed for spring migration. Our range-wide analysis demonstrates the lasting impact breeding latitude can have on migration schedules but also highlights how such timing relationships can reset when individuals reside at non-breeding sites for extended periods of time.
Data from: Individual-based measurements of light intensity provide new insights into the effects of artificial light at night on daily rhythms of urban-dwelling songbirds
1. The growing interest in the effects of light pollution on daily and seasonal cycles of animals has led to a boost of research in recent years. In birds, it has been hypothesized that artificial light at night can affect daily aspects of behaviour, but one caveat is the lack of knowledge about the light intensity that wild animals, such as birds, are exposed to during the night. 2. Organisms have naturally evolved daily rhythms to adapt to the 24-h cycle of day and night, thus, it is important to investigate the potential shifts in daily cycles due to global anthropogenic processes such as urbanization. 3. We captured adult male European blackbirds (Turdus merula) in one rural forest and two urban sites differing in the degree of anthropogenic disturbance. We tagged these birds with light loggers and simultaneously recorded changes in activity status (active/non-active) through an automated telemetry system. We first analysed the relationship between light at night, weather conditions and date with daily activity onset and end. We then compared activity, light at night exposure and noise levels between weekdays and weekends. 4. Onset of daily activity was significantly advanced in both urban sites compared to the rural population, while end of daily activity did not vary either among sites. Birds exposed to higher amounts of light in the late night showed earlier onset of activity in the morning, but light at night did not influence end of daily activity. Light exposure at night and onset/end of daily activity timing was not different between weekdays and weekends, but all noise variables were. A strong seasonal effect was detected in both urban and rural populations, such as birds tended to be active earlier in the morning and later in the evening (relative to civil twilight) in the early breeding season than at later stages. 5. Our results point at artificial light at night as a major driver of change in timing of daily activity. Future research should focus on the costs and benefits of altered daily rhythmicity in birds thriving in urban areas.
Data from: Survival to independence in relation to pre-fledging development and latitude in songbirds across the globe
Species differ strongly in their life histories, including the probability of survival. Annual adult survival was investigated extensively in the past, whereas juvenile survival, and especially survival to independence, received much less attention. Yet, they are critical for our understanding of population demography and life-history evolution. We investigated post-fledging survival to independence (i.e. survival upon leaving the nest until nutritional independence) in 74 species of passerine birds worldwide based on 100 population level estimates extracted from published literature. Our comparative analyses revealed that survival to independence increased with the length of nestling period and relative fledging mass (ratio of fledging mass to adult body mass). At the same time, species with higher nest predation rates had shorter nestling periods and lower relative fledging mass. Thus, we identify an important trade-off in life history strategies: staying longer in the nest may improve post-fledging survival due to enhanced flight ability and sensory functions, but at the cost of a longer exposure to nest predators and increased mortality due to nest predation. Additionally, post-fledging survival to independence did not differ between species from the northern temperate zone vs species from the tropics and southern hemisphere. However, analyses of post-fledging survival curves suggest that 1) daily survival rates are not constant and improve quickly upon leaving the nest, and 2) species in the tropics and southern hemisphere have higher daily post-fledging survival rates than northern temperate species. Nevertheless, due to the accumulation of mortality risk during their much longer periods of post-fledging care, overall survival until independence is comparable across latitudes. Obtaining high-quality demographic data across latitudes to evaluate the generality of these findings and mechanisms underlying them should be a research priority.
Data from: Experimental brood enlargement differentially influences the magnitude of the corticosterone stress response in closely related, co‐occurring songbirds
1. Rearing environments can shape offspring phenotype across taxa, yet little is known about how brood size influences hypothalamic-pituitary axis functioning, whether its expression trades off with growth, and the degree to which these relationships vary between species. 2. We evaluated how brood size influenced nestling physiological (glucocorticoids) and somatic traits (growth), and the extent to which these relationships differed between two closely related, sympatric songbirds when experiencing identical rearing environments. Specifically, we used a cross-fostering approach to alter brood size and create an experimental gradient of nestmate competition, and then tested whether experimentally manipulated brood sizes resulted in nestlings with altered concentrations of corticosterone and if corticosterone responses traded off with growth. 3. Nestlings of both species experienced elevated concentrations of baseline and stressor-induced corticosterone when raised in enlarged broods, relative to control and reduced broods, but neither measurement was found to trade off with growth or be linked to survival to fledging. 4. In contrast, we found divergence in the magnitude of the corticosterone stress response between species across all brood treatments, with greater stressor-induced corticosterone concentrations found in the Violet-green Swallow (Tachycineta thalassina) relative to the closely related Tree Swallow (T. bicolor). 5. Our study demonstrated that brood size can lead to changes in offspring corticosterone concentrations in swallows, and that nestlings of sympatric species, even those that are closely related and ecologically similar, can diverge in their corticosterone stress response when experiencing identical rearing conditions. 6. We conclude that corticosterone appears to play a key role for balancing energetic demands that arise in the face of nestmate competition in Tachycineta swallows, and that elevated concentrations of corticosterone may enhance offspring survival during challenging environmental conditions, such as when brood competition is strong.
Data from: Effect of fuel deposition rate on departure fuel load of migratory songbirds during spring stopover along the northern coast of the Gulf of Mexico
Migrants are generally assumed to minimize their overall migration time by adjusting their departure fuel loads (DFL) in relation to anticipated and experienced fuel deposition rates (FDRs). We utilized a 21-yr long migration banding station dataset to examine the relationship between FDR and DFL during spring migration in six Nearctic-Neotropical migratory songbird species during stopover along the northern coast of the Gulf of Mexico (GOM) following trans-gulf flight. Estimates of fuel stores, stopover durations, and FDRs from our long term migration data set were combined to determine DFL. We expected and found that migrants across all six species adjust their DFL to the rate at which they deposit fuel reserves. This robust finding suggests that songbird migrants are sensitive to time constraints during spring passage presumably to fine-tune their stopover schedule in relation to experienced and anticipated habitat quality. Two of the species studied showed an effect of age on the FDR–DFL relationship: one was consistent with the expectation that older birds would be less sensitive to changes in FDR, while the second was contrary to our expectations and likely suggesting an age-dependent response to habitat quality. We found sex-dependent differences consistent with male DFL being more sensitive to FDR in only two of six species studied, and argue that both males and females are time constrained during spring passage in relation to arrival at breeding destinations. The positive relationship between FDR and DFL among all species and for age and sex groups in some species reflects a migration strategy sensitive to time.
Data from: Deciphering information encoded in birdsong: male songbirds with fertile mates respond most strongly to complex, low-amplitude songs used in courtship
Research on the function of acoustic signals has focused on high-amplitude, long-range song (LRS) and largely ignored low-amplitude songs produced by many species during close-proximity, conspecific interactions. Low-amplitude songs can be structurally identical to LRS (soft LRS) or they can be widely divergent, sharing few spectral and temporal attributes with LRS (short-range song (SRS)). SRS is often more complex than LRS and is frequently sung by males during courtship. To assess function, we performed two playback experiments on males of a socially monogamous songbird. We compared responses of males whose mates were fertile or non-fertile to differences in song structure (SRS v. LRS and soft LRS), amplitude (SRS and soft LRS v. LRS), and tempo (slow v. fast SRS). Males responded more strongly to SRS than to LRS or soft LRS, indicating that song structure had a greater effect on response than song amplitude. SRS tempo did not detectably affect male response. Importantly, males responded more strongly to SRS when their mates were fertile, presumably because hearing SRS can indicate that a male's mate is being courted by an intruding male and a strong response can deter extra-pair competitors. We conclude that low-amplitude songs can function in both inter- and intra-sexual communication and should receive greater attention in future studies of mate choice and male-male competition.
Data from: Migrating songbirds on stopover prepare for, and recover from, oxidative challenges posed by long-distance flight
Managing oxidative stress is an important physiological function for all aerobic organisms, particularly during periods of prolonged high metabolic activity, such as long-distance migration across ecological barriers. However, no previous study has investigated the oxidative status of birds at different stages of migration and whether that oxidative status depends on the condition of the birds. In this study, we compared (1) energy stores and circulating oxidative status measures in (a) two species of Neotropical migrants with differing migration strategies that were sampled at an autumn stopover site before an ecological barrier; and (b) a species of trans-Saharan migrant sampled at a spring stopover site after crossing an ecological barrier; and (2) circulating oxidative measures and indicators of fat metabolism in a trans-Saharan migrant after stopovers of varying duration (0–8 nights), based on recapture records. We found fat stores to be positively correlated with circulating antioxidant capacity in Blackpoll Warblers and Red-eyed Vireos preparing for fall migration on Block Island, USA, but uncorrelated in Garden Warblers on the island of Ponza, Italy, after a spring crossing of the Sahara Desert and Mediterranean Sea. In all circumstances, fat stores were positively correlated with circulating lipid oxidation levels. Among Garden Warblers on the island of Ponza, fat anabolism increased with stopover duration while oxidative damage levels decreased. Our study provides evidence that birds build antioxidant capacity as they build fat stores at stopover sites before long flights, but does not support the idea that antioxidant stores remain elevated in birds with high fuel levels after an ecological barrier. Our results further suggest that lipid oxidation may be an inescapable hazard of using fats as the primary fuel for flight. Yet, we also show that birds on stopover are capable of recovering from the oxidative damage they have accrued during migration, as lipid oxidation levels decrease with time on stopover. Thus, the physiological strategy of migrating songbirds may be to build prophylactic antioxidant capacity in concert with fuel stores at stopover sites before a long-distance flight, and then repair oxidative damage while refueling at stopover sites after long-distance flight.
Data from: A novel locus on chromosome 1 underlies the evolution of a melanic plumage polymorphism in a wild songbird
Understanding the mechanisms responsible for phenotypic diversification within and among species ultimately rests with linking naturally occurring mutations to functionally and ecologically significant traits. Colour polymorphisms are of great interest in this context because discrete colour patterns within a population are often controlled by just a few genes in a common environment. We investigated how and why phenotypic diversity arose and persists in the Zosterops borbonicus white-eye of Reunion (Mascarene archipelago), a colour polymorphic songbird in which all highland populations contain individuals belonging to either a brown or a grey plumage morph. Using extensive phenotypic and genomic data, we demonstrate that this melanin-based colour polymorphism is controlled by a single locus on chromosome 1 with two large-effect alleles, which was not previously described as affecting hair or feather colour. Differences between colour morphs appear to rely upon complex cis-regulatory variation that either prevents the synthesis of pheomelanin in grey feathers, or increases its production in brown ones. We used coalescent analyses to show that, from a 'brown' ancestral population, the dominant 'grey' allele spread quickly once it arose from a new mutation. Since colour morphs are always found in mixture, this implies that the selected allele does not go to fixation, but instead reaches an intermediate frequency, as would be expected under balancing selection.
Data from: Potential age differences in the migratory behaviour of a nocturnal songbird migrant during autumn and spring
In migratory songbirds, older individuals are thought to be more efficient migrants than younger individuals. Age-specific differences in migratory efficiency have been reported mainly in respect of arrival timing, energy stores, rate of energy accumulation, departure behaviour, and departure direction. Yet, these traits were rarely assessed simultaneously in a single species. We further lack information whether age-specific differences in behavioural traits present in autumn still manifest to the same degree in spring. Here we used the northern wheatear (Oenanthe oenanthe), a long-distance nocturnal songbird migrant, and investigated age-specific differences in energy stores at capture (autumn: 1059 birds/spring: 803 birds), rate of energy accumulation (168/147), nocturnal departure timing (126/105), and departure direction (94/77) for both seasons. We found that in autumn, young northern wheatears departed significantly later in the night than older birds. This difference was not observed in spring. The resulting advance in nocturnal departure timing by young birds from autumn to spring may be due to learning based on experience gained during autumn, and/or to selective disappearance of those young individuals showing late departure times during autumn. We found no age-specific difference in any of the other migratory traits investigated. To get a better understanding of age effects in songbird migrants, we need to study the potential adjustments of migratory behaviour within the individual over its life time. By individually tracking songbirds throughout their lifetime, we could start estimating whether a certain migratory decision (fuelling, departure, orientation) translates into higher (or lower) fitness, and whether individuals adjust their migratory behaviour based on learning from "wrong decisions".
Data from: Major histocompatibility complex class I evolution in songbirds: universal primers, rapid evolution and base compositional shifts in exon 3
Genes of the Major Histocompatibility Complex (MHC) have become an important marker for the investigation of adaptive genetic variation in vertebrates because of their critical role in pathogen resistance. However, despite significant advances in the last few years the characterization of MHC variation in non-model species still remains a challenging task due to the redundancy and high variation of this gene complex. Here we report the utility of a single pair of primers for the cross-amplification of the third exon of MHC class I genes, which encodes the more polymorphic half of the peptide-binding region (PBR), in oscine passerines (songbirds; Aves: Passeriformes), a group especially challenging for MHC characterization due to the presence of large and complex MHC multigene families. In our survey, although the primers failed to amplify exon 3 from two suboscine passerine birds, they amplified exon 3 of multiple MHC class I genes in all 16 species of oscine songbirds tested, yielding a total of 120 sequences. The 16 songbird species belong to 14 different families, primarily within the Passerida, but also in the Corvida. Using a conservative approach based on the analysis of cloned amplicons (n = 16) from each species, we found between 3 and 10 MHC sequences per individual. Each allele repertoire was highly divergent, with the overall number of polymorphic sites per species ranging from 33 to 108 (out of 264 sites) and the average number of nucleotide differences between alleles ranging from 14.67 to 43.67. Our survey in songbirds allowed us to compare macroevolutionary dynamics of exon 3 between songbirds and non-passerine birds. We found compelling evidence of positive selection acting specifically upon peptide-binding codons across birds, and we estimate the strength of diversifying selection in songbirds to be about twice that in non-passerines. Analysis using comparative methods suggest weaker evidence for a higher GC content in the 3rd codon position of exon 3 in non-passerine birds, a pattern that contrasts with among-clade GC patterns found in other avian studies and may suggests different mutational mechanisms. Our primers represent a useful toolfor the characterization of functional and evolutionarily relevant MHC variation across the hyperdiverse songbirds.
Data from: Nocturnal migratory songbirds adjust their travelling direction aloft: evidence from a radiotelemetry and radar study
In order to fully understand the orientation behaviour of migrating birds, it is important to understand when birds set their travel direction. Departure directions of migratory passerines leaving stopover sites are often assumed to reflect the birds' intended travel directions, but this assumption has not been critically tested. We used data from an automated radiotelemetry system and a tracking radar at Falsterbo peninsula, Sweden, to compare the initial orientation of departing songbirds (recorded by radiotelemetry) with the orientation of songbird migrants in climbing and level flight (recorded by radar). We found that the track directions of birds at high altitudes and in level flight were more concentrated than the directions of departing birds and birds in climbing flight, which indicates that the birds adjust their travelling direction once aloft. This was further supported by a wide scatter of vanishing bearings in a subsample of radio-tracked birds that later passed an offshore radio receiver station 50 km southeast of Falsterbo. Track directions seemed to be more affected by winds in climbing compared with level flights, which may be explained by birds not starting to partially compensate for wind drift until they have reached cruising altitudes.
Data from: Stressful colors: corticosterone concentrations in a free-living songbird vary with the spectral composition of experimental illumination
Organisms have evolved under natural daily light/dark cycles for millions of years. These cycles have been disturbed as night-time darkness is increasingly replaced by artificial illumination. Investigating the physiological consequences of free-living organisms in artificially lit environments is crucial to determine whether nocturnal lighting disrupts circadian rhythms, changes behaviour, reduces fitness and ultimately affects population numbers. We make use of a unique, large-scale network of replicated field sites which were experimentally illuminated at night using lampposts emanating either red, green, white or no light to test effect on stress hormone concentrations (corticosterone) in a songbird, the great tit (Parus major). Adults nesting in white-light transects had higher corticosterone concentrations than in the other treatments. We also found a significant interaction between distance to the closest lamppost and treatment type: individuals in red light had higher corticosterone levels when they nested closer to the lamppost than individuals nesting farther away, a decline not observed in the green or dark treatment. Individuals with high corticosterone levels had fewer fledglings, irrespective of treatment. These results show that artificial light can induce changes in individual hormonal phenotype. As these effects vary considerably with light spectrum, it opens the possibility to mitigate these effects by selecting street lighting of specific spectra.
Data from: Carotenoid-based bill coloration functions as a social, not sexual, signal in songbirds (Aves: Passeriformes)
Many animals use coloration to communicate with other individuals. While the signalling role of avian plumage colour is relatively well studied, there has been much less research on coloration in avian bare parts. However, bare parts could be highly informative signals as they can show rapid changes in coloration. We measured bill colour (a ubiquitous bare part) in over 1600 passerine species and tested whether interspecific variation in carotenoid-based coloration is consistent with signalling to potential mates or signalling to potential rivals in a competitive context. Our results suggest that carotenoid bill coloration primarily evolved as a signal of dominance, as this type of coloration is more common in species that live in social groups in the non-breeding season, and species that nest in colonies; two socio-ecological conditions that promote frequent agonistic interactions with numerous and/or unfamiliar individuals. Additionally, our study suggests that carotenoid bill coloration is independent of the intensity of past sexual selection, as it is not related to either sexual dichromatism or sexual size dimorphism. These results pose a significant challenge to the conventional view that carotenoid-based avian coloration has evolved as a developmentally costly, condition-dependent sexual signal. We also suggest that bare part ornamentation may often signal different information than plumage ornaments.
Data from: Extra-pair mating opportunities mediate parenting and mating effort trade-offs in a songbird
<p>In socially monogamous species with bi-parental care, males may face a trade-off between providing parental care and pursuing extra-pair matings. The "parenting-mating trade-off" hypothesis predicts that high-quality males – who have greater potential to gain extra-pair matings, e.g. larger males usually win the competition for extra-pair mating – should reduce parental care and spend more time looking for extra-pair matings. However, the trade-off between parenting and mating efforts may be complicated by variation in the availability of extra-pair mating opportunities. By using field data of hair-crested drongos (<i>Dicrurus hottentottus</i>), a species exhibiting bi-parental incubation behavior, collected in central China from 2010 to 2017, we tested whether the potential negative relationship between male quality and paternal care was dependent on the number of nearby fertile females. We found that male drongos mainly seek extra-pair matings during the incubation period and high-quality individuals (males with longer tarsi) are more likely to sire extra-pair offspring. In agreement with the "parenting-mating trade-off" hypothesis, high-quality males incubated less by recessing longer between incubation bouts. However, this was only the case when sufficient fertile females nearby for extra-pair mating opportunities. Females compensated for reduced male care, but this was independent of male quality. This suggests that the reduction in care by high-quality males might be a direct response to extra-pair mating opportunities rather than facilitated by differential allocation of females. Our results indicate that individual quality and available mating opportunities may shape the optimal trade-off between parental care and seeking additional matings for males.</p>
Data from: Differential divergence in autosomes and sex chromosomes is associated with intra-island diversification at a very small spatial scale in a songbird lineage
<p>Recently diverged taxa showing marked phenotypic and ecological diversity are optimal systems to understand the genetic processes underlying speciation. We used genome-wide markers to investigate the diversification of the Reunion grey white eye (<i>Zosterops borbonicus</i>) on the small volcanic island of Reunion (Mascarene archipelago), where this species complex exhibits four geographic forms that are parapatrically distributed across the island and differ strikingly in plumage colour. One form restricted to the highlands is separated by a steep ecological gradient from three distinct lowland forms which meet at narrow hybrid zones that are not associated with environmental variables. Analyses of genomic variation based on SNP data from genotyping-by-sequencing and pooled RADseq approaches, reveal that signatures of selection associated with elevation can be found at multiple regions across the genome, whereas most loci associated with the lowland forms are located on the Z sex chromosome. We identified <i>TYRP1</i>, a Z-linked colour gene, as a likely candidate locus underlying colour variation among lowland forms. Tests of demographic models revealed that highland and lowland forms diverged in the presence of gene flow, and divergence has progressed as gene flow was restricted by selection at loci across the genome. This system is promising to investigate how natural selection and reproductive isolation shape the genomic landscape of divergence at multiple stages of the speciation process.</p>
Data from: Linking songbird nest predation to seedling density: sugar maple masting as a resource pulse in a forest food web
The ecological literature presents considerable evidence for top-down forcing on the maintenance of species diversity. Yet, in temperate forests, bottom-up forces often exert a strong influence on ecosystem functioning. Here, we report on the indirect influence of a pulsed resource, sugar maple (Acer saccharum) seed production, on nest survival in a migratory songbird. We hypothesized that seed production in year t would determine daily nest survival rate in year t + 1 through its effects on seed-eating rodents. We used the density of sugar maple seedlings (with cotyledons) in year t + 1 as a proxy for seed production in year t and predicted that it would be inversely related to songbird nest survival the same year. We estimated the density of sugar maple seedlings, eastern chipmunk (Tamias striatus) activity, and daily nest survival rate in the ovenbird (Seiurus aurocapilla) over four successive years in a northern hardwood forest of New Brunswick, Canada. Seedling density varied by two orders of magnitude between years, whereas an index of chipmunk activity changed by an order of magnitude. Both variables were positively correlated and negatively correlated to daily nest survival rate. A logistic-exposure model including only seedling density received the greatest level of support (lowest AICc). Previous studies have reported the effect of sugar maple masting on seed-eating rodent populations, but the strong link we report between seedling density and songbird nest survival is novel. A nocturnal seed-eating nest predator, deer mouse (Peromyscus maniculatus), was not considered in our models, which may explain why chipmunk was not the best predictor of daily nest survival rate. The trophic linkages we observed are remarkably strong for a temperate forest ecosystem and might become more prevalent in northeastern North America, at least on calcium-rich soils, with the loss of large-diameter beech trees as a result of beech bark disease.
Data from: Genetic variation in variability: phenotypic variability of fledging weight and its evolution in a songbird population
Variation in traits is essential for natural selection to operate and genetic and environmental effects can contribute to this phenotypic variation. From domesticated populations, we know that families can differ in their level of within-family variance, which leads to the intriguing situation that within-family variance can be heritable. For offspring traits, such as birth weight, this implies that within-family variance in traits can vary among families and can thus be shaped by natural selection. Empirical evidence for this in wild populations is however lacking. We investigated whether within-family variance in fledging weight is heritable in a wild great tit (Parus major) population and whether these differences are associated with fitness. We found significant evidence for genetic variance in within-family variance. The genetic coefficient of variation (GCV) was 0.18 and 0.25, when considering fledging weight a parental or offspring trait, respectively. We found a significant quadratic relationship between within-family variance and fitness: families with low or high within-family variance had lower fitness than families with intermediate within-family variance. Our results show that within-family variance can respond to selection and provides evidence for stabilizing selection on within-family variance.
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Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.