43 research outputs found

    Weather Conditions Drive Dynamic Habitat Selection in a Generalist Predator

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    <div><p>Despite the dynamic nature of habitat selection, temporal variation as arising from factors such as weather are rarely quantified in species-habitat relationships. We analysed habitat use and selection (use/availability) of foraging, radio-tagged little owls (<i>Athene noctua</i>), a nocturnal, year-round resident generalist predator, to see how this varied as a function of weather, season and availability. Use of the two most frequently used land cover types, gardens/buildings and cultivated fields varied more than 3-fold as a simple function of season and weather through linear effects of wind and quadratic effects of temperature. Even when controlling for the temporal context, both land cover types were used more evenly than predicted from variation in availability (functional response in habitat selection). Use of two other land cover categories (pastures and moist areas) increased linearly with temperature and was proportional to their availability. The study shows that habitat selection by generalist foragers may be highly dependent on temporal variables such as weather, probably because such foragers switch between weather dependent feeding opportunities offered by different land cover types. An opportunistic foraging strategy in a landscape with erratically appearing feeding opportunities in different land cover types, may possibly also explain decreasing selection of the two most frequently used land cover types with increasing availability.</p></div

    Use of land cover types by radio-tagged little owls in May–August (warm season) and September–April (cold season) plotted/regressed against availability at home range level and within distance-to-nest intervals.

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    <p>At the home range level, each dot represents the proportion of time (telemetry fixes) one owl spent in the land cover category. Regression lines show back-transformed predictions from logit-transformed response variables regressed on logit-transformed proportional cover values (thin lines indicate 95% confidence zones). Predictions above the line y = x suggest that a land cover type is used more than expected by availability; predictions below the line that it is used less than availability would predict. The state space of graphs for distance-to-nest intervals represents the 98%-mid fraction of the availabilities observed.</p

    Slopes (<i>b</i>) of logistic regression coefficients of the probability that radio-tagged little owls would use focal land cover categories as functions of their logit-transformed (‘availability’) at home range level and at the distance-to-nest interval level.

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    <p><i>P</i>-values are given for the explicit nil-hypotheses of use being independent of variation in availability (H<sub>0</sub>: <i>b</i> = 0) or proportional to availability (H<sub>0</sub>: <i>b</i> = 1). The slopes originate from models that also included influence of owl identity (random effect), month and weather variables (Tables B–C in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0088221#pone.0088221.s003" target="_blank">File S3</a>).</p

    Nocturnal dispersion of four radio-tagged little owls from two pairs.

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    <p>Colour codes indicate whether the owls were perching or were located on the ground, as evident from the strength and echo patterns of the radio signals. Concentric lines 20–800 m from the nest/roosting sites indicate the total area with distance intervals within which habitat use and availability was compared.</p

    Bill measurements of hummingbirds in the ecological network database

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    Here you will find the bill measurements of 161 hummingbird species. This is the set of species present in the network database that describes the interactions between these hummingbirds and their nectar resources (Dalsgaard et al. 2011, Martin-Gonzalez et al. 2015, Maruyama et al. 2018, Sonne et al. in press). Detailed information about the measurements can be found at the enclosed documents

    MCC phylogeny of 782 species of the Corvides

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    This phylogeny was largely based on that from the study Jønsson et al. (2016), which generated a time-calibrated tree using sequence data from 665 species of the Corvides. The remaining 124 species (as recognized by the IOC 2.7) which had no sequence data available at the time of the tree generation were added as polytomies to the maximum clade credibility (MCC) tree of Jønsson et al. (2016) using current taxonomic information. The branch lengths subtending these species were inferred using the polytomy resolution method. Subsequently, we pruned out 7 species for which wing measurements were unavailable