Dataset Information

Shifts in timing and duration of breeding for 73 boreal bird species over four decades.

ABSTRACT: Breeding timed to match optimal resource abundance is vital for the successful reproduction of species, and breeding is therefore sensitive to environmental cues. As the timing of breeding shifts with a changing climate, this may not only affect the onset of breeding but also its termination, and thus the length of the breeding period. We use an extensive dataset of over 820K nesting records of 73 bird species across the boreal region in Finland to probe for changes in the beginning, end, and duration of the breeding period over four decades (1975 to 2017). We uncover a general advance of breeding with a strong phylogenetic signal but no systematic variation over space. Additionally, 31% of species contracted their breeding period in at least one bioclimatic zone, as the end of the breeding period advanced more than the beginning. We did not detect a statistical difference in phenological responses of species with combinations of different migratory strategy or number of broods. Nonetheless, we find systematic differences in species responses, as the contraction in the breeding period was found almost exclusively in resident and short-distance migrating species, which generally breed early in the season. Overall, changes in the timing and duration of reproduction may potentially lead to more broods co-occurring in the early breeding season-a critical time for species' reproductive success. Our findings highlight the importance of quantifying phenological change across species and over the entire season to reveal shifts in the community-level distribution of bird reproduction.

SUBMITTER: Hallfors MH

PROVIDER: S-EPMC7414193 | biostudies-literature | 2020 Aug

REPOSITORIES: biostudies-literature

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Shifts in timing and duration of breeding for 73 boreal bird species over four decades.

Hällfors Maria H MH Antão Laura H LH Itter Malcolm M Lehikoinen Aleksi A Lindholm Tanja T Roslin Tomas T Saastamoinen Marjo M

Proceedings of the National Academy of Sciences of the United States of America 20200720 31

Breeding timed to match optimal resource abundance is vital for the successful reproduction of species, and breeding is therefore sensitive to environmental cues. As the timing of breeding shifts with a changing climate, this may not only affect the onset of breeding but also its termination, and thus the length of the breeding period. We use an extensive dataset of over 820K nesting records of 73 bird species across the boreal region in Finland to probe for changes in the beginning, end, and du ...[more]

PMID: 32690693

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Project description:Knowledge of the temporal variation in reproductive success and its key driving factors is crucial in predicting animal population persistence. Few studies have examined the effects of a range of explanatory factors operating simultaneously on the same population over a long period. Based on 41 years of monitoring (1979-2019), we tested prevailing hypotheses about drivers of annual variation in breeding success in two sympatric species of boreal forest grouse-the capercaillie (Tetrao urogallus) and the black grouse (T. tetrix)-in a 45 km2 boreal forest landscape. From counts in early August, we measured breeding success (chicks/hen) along with potential determining factors. We formulated five main hypotheses on causes of variation (hen condition, chick weather, chick food, predation, demographic characteristics) and derived 13 associated explanatory variables for analysis. We first tested the five hypotheses separately and then used model selection (AICc) to rank the best predictive models irrespective of hypotheses. Lastly, we used path analysis to illuminate potential causal relationships. Barring demographic characteristics, all hypotheses were supported, most strongly for chick food and predation. Among predictor variables, chick food (insect larvae and bilberry fruit crops), vole and fox abundances, the winter-NAO index, and temperature after hatching, had the strongest effect sizes in both species. Precipitation after hatching had no detectable effect. Model selection indicated bottom-up factors to be more important than predation, but confounding complicated interpretation. Path analysis suggested that the high explanatory power of bilberry fruiting was due not only to its direct positive effect on chick food quality but also to an indirect positive effect on vole abundance, which buffers predation. The two components of breeding success-proportion of hens with broods and number of chicks per brood-were uncorrelated, the former having the strongest effect. The two components had different ecological correlates that often varied asynchronously, resulting in overall breeding success fluctuating around low to moderate levels. Our study highlights the complexity of key explanatory drivers and the importance of considering multiple hypotheses of breeding success. Although chick food appeared to equal or surpass predation in explaining the annual variation in breeding success, predation may still be the overall limiting factor. Comparative and experimental studies of confounded variables (bilberry fruiting, voles, and larvae) are needed to disentangle causes of variation in breeding success of boreal forest grouse.

Project description:ObjectiveAs the number of female medical students and surgical residents increases, the increasing number of female academic surgeons has been disproportionate. The purpose of this brief report is to evaluate the AAMC data from 1969 to 2018 to compare the level of female academic faculty representation for surgical specialties over the past four decades.DesignThe number of women as a percentage of the total surgeons per year were recorded for each year from 1969-2018, the most recent year available. Descriptive statistics were performed. Poisson regression examined the percentage of women in each field as the outcome of interest with the year and specialty (using general surgery as a reference) as two predictor variables.SettingData from the American Association of Medical Colleges (AAMC).ParticipantsAll full-time academic faculty physicians in the specialties of obstetrics and gynecology (OB/GYN), general surgery, ophthalmology, otolaryngology (ENT), plastic surgery, plastic surgery, urology, neurosurgery, orthopaedic surgery and cardiothoracic surgery as per AAMC records.ResultsThe percentage of women in surgery for all specialties evaluated increased from 1969 to 2018 (OR 1.04, p<0.001). Compared with general surgery, the rate of yearly percentage change increased more slowly in neurosurgery (OR 0.84; P = .004), orthopaedic surgery (OR 0.82; P = .002), urology (OR 0.59; P < .001), and cardiothoracic surgery (OR 0.38; P < .001). There was no significant difference in the rate of yearly percentage change for plastic surgery (OR 1.01; P = .840). The rate of yearly percentage change increased more rapidly in OB/GYN (OR 2.86; P < .001), ophthalmology (OR 1.79; P < .001) and ENT (OR 1.70; P < .001).ConclusionsRepresentation of women in academic surgery is increasing overall but is increasing more slowly in orthopaedic surgery, neurosurgery, cardiothoracic surgery and urology compared with that in general surgery. These data may be used to inform and further the discussion of how mentorship and sponsorship of female students and trainees interested in surgical careers may improve gender equity in the future.

Dataset Information

Shifts in timing and duration of breeding for 73 boreal bird species over four decades.

Publications

Shifts in timing and duration of breeding for 73 boreal bird species over four decades.

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