Find research datasets worth reusing

opencc-zeroDec 2014View details →

Data from: Experimental effects of early-life corticosterone on the HPA axis and pre-migratory behaviour in a wild songbird

1.Although laboratory studies have shown that chronic exposure to elevated glucocorticoids during development can have profound effects on the physiology and behaviour of animals, we still have a poor understanding of the proximate and ultimate consequences of early-life stress on individuals in the wild. 2. In an island population of Savannah sparrows (Passerculus sandwichensis), we examined multiple hypotheses to explain how elevated glucocorticoid exposure during the nestling period influenced both hypothalamic-pituitary-adrenal (HPA) axis function during the nestling period and the subsequent movement and survival of young after they fledged the nest. 3. We exposed nestlings to exogenous corticosterone from 2-6 d of age and then measured both baseline and stress-induced (30 min restraint) plasma corticosterone levels prior to fledging (d 7). We then recaptured young throughout the pre-migratory period and used mark-recapture analysis to estimate temporary emigration from the capture site (movement) and survival. 4. Corticosterone-treated nestlings had higher baseline corticosterone levels and lower stress reactivity than untreated individuals, and were more sensitive to inclement weather. Although there was no evidence that corticosterone treatments influenced survival, treated individuals had higher rates of temporary emigration outside of the study site than sham or controls. 5. Our results provide support for the ceiling hypothesis, which suggests that individuals with chronic elevated glucocorticoids can lead to a dampened HPA axis response. We also provide support for the CORT-activity hypothesis, which suggests that elevated glucocorticoids can increase activity levels, at least 1-2 months after leaving the nest. Our study highlights the importance of tracking individuals across multiple stages of the annual cycle to understand how early life events carry-over to influence both physiology and behaviour.

opencc-zeroDec 2015View details →

Data from: Influence of landscape features on the microgeographic genetic structure of a resident songbird.

Landscape features influence individual dispersal and as a result can affect both gene flow and genetic variation within and between populations. The landscape of British Columbia, Canada, is already highly heterogeneous due to natural ecological and geological transitions, but disturbance from human-mediated processes has further fragmented continuous habitat, particularly in the central plateau region. In this study, we evaluated the effects of landscape heterogeneity on the genetic structure of a common resident songbird, the black-capped chickadee (Poecile atricapillus). Previous work revealed significant population structuring in British Columbia which could not be explained by physical barriers, so our aim was to assess the pattern of genetic structure at a microgeographic scale and determine the effect of different landscape features on genetic differentiation. A total of 399 individuals from 15 populations were genotyped for fourteen microsatellite loci revealing significant population structuring in this species. Individual and population-based analyses revealed as many as nine genetic clusters with isolation in the north, the central plateau and the south. Moreover, a mixed modelling approach that accounted for non-independence of pairwise distance values revealed a significant effect of land cover and elevation resistance on genetic differentiation. These results suggest that barriers in the landscape influence dispersal which has led to the unexpectedly high levels of population isolation. Our study demonstrates the importance of incorporating landscape features when interpreting patterns of population differentiation. Despite taking a microgeographic approach, our results have opened up additional questions concerning the processes influencing dispersal and gene flow at the local scale.

opencc-zeroDec 2016View details →

Data from: Cryptic speciation and gene flow in a migratory songbird species complex: insights from the red-eyed vireo (Vireo olivaceus)

Migratory species that alternate between sympatry and allopatry over the course of an annual cycle are promising subjects for studies seeking to understand the process of speciation in the absence of strict geographic isolation. Here we sought to identify cryptic species and assess rates of gene flow in a clade of neotropical migrant songbirds in which geography and taxonomy are currently out of sync: the Red-Eyed Vireo (V. olivaceus) Species Complex. Phylogenetic, clustering, and statistical species delimitation analyses found that V. olivaceus includes two non-sister lineages migrating in opposite directions across the equator. Analyses of gene flow identified low levels of introgression between two species pairs, but none between northern and southern olivaceus. We also identified substantial well-supported conflicts between nuclear and mitochondrial topologies. Although the geographic distribution of mito-nuclear discordance is suggestive of hybridization and mitochondrial capture, we found no evidence of introgression in the nuclear genome of populations with discordant mitochondrial gene trees. Our study finds that species boundaries match breeding range and migratory phenology rather than the existing taxonomy in this group, and demonstrates the utility of genomic data in inferring species boundaries in recently diverged clades.

FIGURES 19–20 in Four new species of Brueelia Kéler, 1936 (Phthiraptera: Ischnocera: Philopteridae) from African songbirds (Passeriformes: Sturnidae and Laniidae)

FIGURES 19–20. Male heads, dorsal and ventral views. 19, Brueelia tkachi n. sp. 20, Brueelia coryliventer n. sp.

FIGURES 13–16 in Four new species of Brueelia Kéler, 1936 (Phthiraptera: Ischnocera: Philopteridae) from African songbirds (Passeriformes: Sturnidae and Laniidae)

FIGURES 13–16. Female subgenital plates and vulval margins, ventral views. 13, Brueelia clara n. sp. 14, Brueelia rigbyi n. sp. 15, Brueelia tkachi n. sp. 16, Brueelia coryliventer n. sp. Abbreviations: vms = vulval marginal setae; vos = vulval oblique setae; vss = vulval submarginal setae.

FIGURES 9–12. Male genitalia, dorsal views. 9, Brueelia clara n in Four new species of Brueelia Kéler, 1936 (Phthiraptera: Ischnocera: Philopteridae) from African songbirds (Passeriformes: Sturnidae and Laniidae)

FIGURES 9–12. Male genitalia, dorsal views. 9, Brueelia clara n. sp. 10, Brueelia rigbyi n. sp. 11, Brueelia tkachi n. sp. 12, Brueelia coryliventer n. sp. Abbreviations: lf = lateral fold; mf = median fold.

FIGURES 17–18 in Four new species of Brueelia Kéler, 1936 (Phthiraptera: Ischnocera: Philopteridae) from African songbirds (Passeriformes: Sturnidae and Laniidae)

FIGURES 17–18. Male heads, dorsal and ventral views. 17, Brueelia clara n. sp. 18, Brueelia rigbyi n. sp. Abbreviations: ads = anterior dorsal seta; as1–2 = anterior setae 1–2; avs1–3 = anterior ventral setae 1–3; dsms = dorsal submarginal seta; mds = mandibular seta; mts1–5 = marginal temporal setae 1–5; os = ocular seta; pcs = preconal seta; pas = preantennal seta; pos = preocular seta; pts = post-temporal seta; s1–4 sensilla 1–4; vsms1–2 = ventral submarginal setae 1–2.

FIGURES 3–4 Brueelia rigbyi n in Four new species of Brueelia Kéler, 1936 (Phthiraptera: Ischnocera: Philopteridae) from African songbirds (Passeriformes: Sturnidae and Laniidae)

FIGURES 3–4 Brueelia rigbyi n. sp. ex Corvinella melanoleuca. 3, male habitus, dorsal and ventral views. 4, female habitus, dorsal and ventral views.

FIGURES 7–8. Brueelia coryliventer n in Four new species of Brueelia Kéler, 1936 (Phthiraptera: Ischnocera: Philopteridae) from African songbirds (Passeriformes: Sturnidae and Laniidae)

FIGURES 7–8. Brueelia coryliventer n. sp. ex Creatophora cinerea. 7, male habitus, dorsal and ventral views. 8, female habitus, dorsal and ventral views.

FIGURES 5–6. Brueelia tkachi n in Four new species of Brueelia Kéler, 1936 (Phthiraptera: Ischnocera: Philopteridae) from African songbirds (Passeriformes: Sturnidae and Laniidae)

FIGURES 5–6. Brueelia tkachi n. sp. ex Spreo albicapillus albicapillus. 5, male habitus, dorsal and ventral views. 6, female habitus, dorsal and ventral views.

FIGURES 1–2. Brueelia clara n in Four new species of Brueelia Kéler, 1936 (Phthiraptera: Ischnocera: Philopteridae) from African songbirds (Passeriformes: Sturnidae and Laniidae)

FIGURES 1–2. Brueelia clara n. sp. ex Lamprotornis australis. 1, male habitus, dorsal and ventral views. 2, female habitus, dorsal and ventral views. Abbreviations: aps = accessory post-spiracular seta; ps = pleural seta; psps post-spiracular principal seta; ss = sutural seta; sts = sternal seta; tps = tergal posteror seta.

opencc-zeroNov 2021View details →

Data from: Vertical sexual habitat segregation in a wintering migratory songbird

Sexual habitat segregation during the wintering period is a widespread phenomenon and has important implications for the ecology and conservation of migratory birds. We studied Black-and-white Warblers (Mniotilta varia) wintering in second-growth scrub and old-growth mangrove forest in Jamaica to quantify sexual habitat segregation and explore whether patterns of habitat occupation have consequences on physical condition. We then used this information along with a body size analysis and simulated territorial intrusions to assess whether behavioral dominance or habitat specialization was responsible for habitat segregation. Based on standardized capture data, we found that females were more abundant than males in both scrub and mangrove forests. Foraging observations, however, suggested vertical segregation within each habitat, with females foraging primarily near the ground and males in the mid-canopy and canopy, indicating that our sex ratio estimates may be biased. Using 2 measures of body condition, we show that males were in better body condition than females, regardless of habitat. We found that males were on average slightly larger than females, and home range analysis and simulated territorial intrusions indicated that males were more territorial than females. We argue that the observed vertical sexual habitat segregation is likely caused by behavioral dominance rather than habitat specialization. Winter body condition is known to carry-over to affect migration timing, reproductive success, and annual survival in other songbirds, and therefore sexual habitat segregation may have important implications for year-round population dynamics in Black-and-white Warblers.

opencc-zeroNov 2021View details →

Complex post-breeding moult strategies in a songbird migrating along the East Asian flyway, the Pallas's Grasshopper Warbler Locustella certhiola

Moult strategies have received relatively little attention in current ornithology, and knowledge concerning the evolution, variability, and extent of moult is sparse in many bird species. This is especially true for East Asian Locustella species where assumptions on moult patterns are based on incomplete information. We provide evidence indicating a complex post-breeding moult strategy and variable moult extent among Pallas's Grasshopper Warbler Locustella certhiola, based on data from six ringing sites situated along its flyway from the breeding grounds to the wintering areas. A detailed study revealed for the first time that in most individuals wing feather moult proceeds from the centre both towards the body and the wing-tip, a moult pattern known as partial divergent moult (which is rare among Palaearctic passerines). In the Russian Far East, where both breeding birds and passage migrants occur, a third of the adult birds were moulting in late summer. In Central Siberia, at the northwestern limit of its distribution, adult individuals commenced their primary moult partly divergently and partly with unknown sequence. During migration in Mongolia, only descendantly (i.e. from the body towards the wing-tip) moulting birds were observed, while further south in Korea, Hong Kong and Thailand the proportion of potential eccentric and divergent feather renewal was not identifiable since the renewed feathers were already fully grown as expected. We found an increase in the mean number of moulted primaries during the progress of the autumn migration. Moderate body mass levels and low fat and muscle scores were observed in moulting adult birds, without any remarkable increase in the later season. According to optimality models, we suggest that an extremely short season of high food abundance in tall grass habitats and a largely overland route allow autumn migration with low fuel loads combined with moult-migration in at least a part of the population. This study highlights the importance of further studying moult strategy as well as stopover behaviour decisions and the trade-offs among migratory birds that are now facing a panoply of anthropogenic threats along their flyways.

opencc-zeroJan 2022View details →

Experimental manipulation of photoperiod influences migration timing in a wild, long-distance migratory songbird

Previous laboratory studies have demonstrated the role of photoperiod in cueing the migration timing of small land birds; however, how migration timing of young birds in wild environments develops in relation to these cues have rarely been investigated. Such investigations can make important contributions to our developing understanding of the phenotypic plasticity of migration timing to new conditions with climate change, where changes in the timing of nesting may expose juvenile birds to different photoperiods. We investigated the impact of manipulating photoperiod during nestling development in a long-distance migratory songbird on the timing of post-breeding movements in the wild. Using programmable lighting installed in the nest-boxes of purple martins (Progne subis), we exposed developing nestlings, from hatch to fledge date, to an extended photoperiod that matched the day length of the summer solstice in Manitoba, Canada. We found that birds with a simulated, earlier photoperiod had a longer nesting period and later fledge and autumn departure dates than control group birds. This study demonstrates the phenotypic plasticity of first-year birds to the ontogenetic effect of their hatch date in the formation of the timing of their first post-breeding movements. Further, we discuss how these results have implications for the potential use of assisted evolution approaches to alter migration timing to match new conditions with climate change.

opencc-zeroJan 2022View details →

Spatiotemporal variation in hatching success and nestling sex ratios track rapid movement of a songbird hybrid zone

Hybridization often occurs at the parapatric range interface between closely related species, but fitness outcomes vary: hybrid offspring exhibit diverse rates of viability and reproduction when compared to their parental species. The mobile hybrid zone between two chickadee congeners ( Poecile atricapillus x P. carolinensis ) has been well studied behaviorally and genetically but the viability of hybrids, as well as the underlying mechanisms contributing to hybrid fitness, have remained unclear. To better characterize the fitness costs of hybridization in this system, we analyzed 21 years of data from four sites, including over 1,400 breeding attempts by the two species, to show that rates of hatching success changed substantially as the zone of hybridization moved across the landscape. Admixture-associated declines in hatching success correlated with reduced proportions of heterogametic (female) offspring as predicted by Haldane's rule. Our data support an underlying mechanism implicating genetic admixture of the homogametic (male) parent as the primary determinant of offspring sex ratio, via incompatibilities on the hemizygous Z chromosome. Our long-term study is the first to directly measure changes in fitness costs as a vertebrate hybrid zone moves, and it shows that changes in these costs are a way to track the distribution of a hybrid zone across the landscape.

opencc-zeroMar 2022View details →

A tail of plumage colouration: disentangling geographic, seasonal, and dietary effects on plumage colour in a migratory songbird

Plumage ornamentation in birds serves critical inter- and intra-sexual signaling functions. While carotenoid-based plumage colouration is often viewed as a classic condition dependent sexually selected trait, plumage colouration can be influenced by a wide array of both intrinsic and extrinsic factors. Understanding the mechanisms underlying variation in colouration is especially important for species where the signaling function of ornamental traits is complex or the literature conflicting. Here, we examined variation in the yellow/orange tail feathers of American redstarts (Setophaga ruticilla) passing through two migratory stopover sites in eastern North America during both spring and fall migration to assess the role of geographic variation and seasonality in influencing feather colouration. In addition, we investigated whether diet during moult (inferred via stable isotope analysis of feather δ15N and δ13C) influenced plumage colouration. Our findings indicate that geographic variation, season, and diet all influence individual differences in American redstart colouration, represented by both traditional and tetrahedral colour variables. The extent to which these factors influence colour expression however is largely dependent on the colour metric under study, likely because different colour metrics reflect different attributes of the feather (e.g., structural components vs. pigment deposition). The effects of diet (δ15N) and season were pronounced for brightness, suggesting a strong effect of diet and feather wear/degradation on feather structure. Though hue, a metric that should strongly reflect pigment deposition, also changed from spring to fall, that effect was dependent on age, with only adults experiencing a reduction in ornamentation. Taken together, our results highlight the numerous sources of variation behind plumage coloration and underscores the difficulty of unraveling complex visual signaling systems, such as those in American redstarts.

opencc-zeroMar 2022View details →

Proximate and evolutionary sources of variation in offspring energy expenditure in songbirds

Aim: Understanding variation in offspring energy expenditure is important because energy is critical for growth and development. Weather may exert proximate effects on offspring energy expenditure, but in altricial species these might be masked by parental care and huddling with siblings. Such effects are particularly important to understand given changing global weather patterns, yet studies of wild offspring in the presence of parental care are lacking. Offspring energy expenditure may also vary among species due to evolved responses to environmental selection pressures, requiring studies at both proximate and ultimate levels. Location: USA, South Africa, Malaysia. Time period: 2016-2019. Major taxa studied: Songbirds. Methods: We used the doubly-labeled water technique to estimate nestling daily energy expenditure of 54 songbird species across three continents. We used Bayesian phylogenetic mixed models to test proximate and evolutionary causes of variation in offspring energy expenditure while accounting for phylogeny and phylogenetic uncertainty. Results: Offspring energy expenditure increased with more rainfall and colder air temperatures, but decreased among offspring in broods with more siblings. Across species, nestling and adult mortality, but not growth rate, were positively associated with offspring energy use. Main conclusions: Weather had clear proximate effects on offspring energy expenditure and parents were either unable or unwilling to fully offset these effects. However, the decrease in offspring energy use when huddling with more siblings demonstrated a modulating effect of life history traits. For example, high nest predation rates favor reduced parental care and can force offspring to spend more energy coping with environmental conditions. Furthermore, reduced energy expenditure is thought to facilitate increased longevity, which is increasingly realized with lower extrinsic mortality rates, providing an explanation for the positive association between adult mortality and offspring energy expenditure. Ultimately, both proximate and evolutionary influences need to be considered to better understand causes of offspring energetics.

opencc-by-4.0Jun 2022View details →

Songbird Activity

This study was conducted in Burnaby, British Columbia between April 15, 2022 and June 21, 2022. Using a Samsung Galaxy J320W8, I have compiled 369 recordings of songbird activity including song sparrows, chickadees, towhees and warblers. These songbirds are among the most prominent in Southwestern British Columbia. For the purpose of this project, I have used the free version of the AlfredCamera application, which gets triggered by any motion and records up to 30 seconds of footage in mp4 format. The intent of this project is multi-fold: - Study songbird activity in urban areas, - Quantify the suitability to songbirds of an urban yard given its proximity to dwellings, noise level and vegetation type, - Analyze the songbird population by using statistical tools, - Paint an accurate picture of the songbird population, - Create a reliable tool to enable citizen scientists to replicate this experiment and gather useful information to ensure the existence of vegetation and greenery in which songbirds thrive.

opencc-zeroAug 2022View details →

Agriculture is adapting to phenological shifts caused by climate change, but grassland songbirds are not

Migratory birds time their migration based on cues that signal resource availability for reproduction. However, with climate change, the timing of seasonal events may shift, potentially inhibiting the ability of some species to use them as accurate cues for migration. We studied the relationship between phenological shifts and reproduction by long- and short-distance migratory songbirds—Bobolinks (Dolichonyx oryzivorus) and Savannah Sparrows (Passerculus sandwichensis). Our study population breeds in hayfields and pastures in Vermont, USA, where farmers are also changing management activities in response to climate change. From 2002-2019 we monitored nest initiation dates to quantify correlations with environmental factors and the timing of nest initiation. We collected historical and projected precipitation and temperature data for the breeding grounds, and their respective wintering and stopover sites, the North Atlantic Oscillation (NAO) and the El Niño Southern Oscillation (ENSO). We predicted that winter conditions experienced by the short-distance migrant, the Savannah Sparrow, but not the long-distance migrant, the Bobolink, would explain the timing and success of nesting, however that this timing would be misaligned with changes in agricultural practices by hay farmers. Nest initiation dates did not show significant directional change for either species, but did vary among years. Interannual variation in Savannah Sparrow nest initiation dates was best explained by the interaction between precipitation on the breeding grounds and average wintering site (Wilmington, North Carolina). For Bobolinks, interannual variation in nest initiation dates was best explained by the interaction between breeding ground precipitation and average temperature in their fall stopover site (Barquisimieto, Venezuela). However, first haying dates in Vermont advanced by ~10 days over 18 years. These results suggest that the conflict between the timing of hay harvests and grassland songbird reproduction will increase, further threatening population processes for these species, as early harvests notably decrease annual productivity.