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  • 1
    Online Resource
    Online Resource
    The Royal Society ; 2015
    In:  Biology Letters Vol. 11, No. 12 ( 2015-12), p. 20150777-
    In: Biology Letters, The Royal Society, Vol. 11, No. 12 ( 2015-12), p. 20150777-
    Abstract: New Caledonian crows are renowned for their unusually sophisticated tool behaviour. Despite decades of fieldwork, however, very little is known about how they make and use their foraging tools in the wild, which is largely owing to the difficulties in observing these shy forest birds. To obtain first estimates of activity budgets, as well as close-up observations of tool-assisted foraging, we equipped 19 wild crows with self-developed miniature video cameras, yielding more than 10 h of analysable video footage for 10 subjects. While only four crows used tools during recording sessions, they did so extensively: across all 10 birds, we conservatively estimate that tool-related behaviour occurred in 3% of total observation time, and accounted for 19% of all foraging behaviour. Our video-loggers provided first footage of crows manufacturing, and using, one of their most complex tool types—hooked stick tools—under completely natural foraging conditions. We recorded manufacture from live branches of paperbark ( Melaleuca sp.) and another tree species (thought to be Acacia spirorbis ), and deployment of tools in a range of contexts, including on the forest floor. Taken together, our video recordings reveal an ‘expanded’ foraging niche for hooked stick tools, and highlight more generally how crows routinely switch between tool- and bill-assisted foraging.
    Type of Medium: Online Resource
    ISSN: 1744-9561 , 1744-957X
    Language: English
    Publisher: The Royal Society
    Publication Date: 2015
    detail.hit.zdb_id: 2103283-X
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    Public Library of Science (PLoS) ; 2013
    In:  PLoS ONE Vol. 8, No. 9 ( 2013-9-10), p. e73733-
    In: PLoS ONE, Public Library of Science (PLoS), Vol. 8, No. 9 ( 2013-9-10), p. e73733-
    Type of Medium: Online Resource
    ISSN: 1932-6203
    Language: English
    Publisher: Public Library of Science (PLoS)
    Publication Date: 2013
    detail.hit.zdb_id: 2267670-3
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  • 3
    In: Methods in Ecology and Evolution, Wiley, Vol. 11, No. 2 ( 2020-02), p. 316-332
    Abstract: To understand the function of colour signals in nature, we require robust quantitative analytical frameworks to enable us to estimate how animal and plant colour patterns appear against their natural background as viewed by ecologically relevant species. Due to the quantitative limitations of existing methods, colour and pattern are rarely analysed in conjunction with one another, despite a large body of literature and decades of research on the importance of spatio‐chromatic colour pattern analyses. Furthermore, key physiological limitations of animal visual systems such as spatial acuity, spectral sensitivities, photoreceptor abundances and receptor noise levels are rarely considered together in colour pattern analyses. Here, we present a novel analytical framework, called the Quantitative Colour Pattern Analysis (QCPA). We have overcome many quantitative and qualitative limitations of existing colour pattern analyses by combining calibrated digital photography and visual modelling. We have integrated and updated existing spatio‐chromatic colour pattern analyses, including adjacency, visual contrast and boundary strength analysis, to be implemented using calibrated digital photography through the Multispectral Image Analysis and Calibration (MICA) Toolbox. This combination of calibrated photography and spatio‐chromatic colour pattern analyses is enabled by the inclusion of psychophysical colour and luminance discrimination thresholds for image segmentation, which we call ‘Receptor Noise Limited Clustering’, used here for the first time. Furthermore, QCPA provides a novel psycho‐physiological approach to the modelling of spatial acuity using convolution in the spatial or frequency domains, followed by ‘Receptor Noise Limited Ranked Filtering’ to eliminate intermediate edge artefacts and recover sharp boundaries following smoothing. We also present a new type of colour pattern analysis, the ‘local edge intensity analysis’ as well as a range of novel psycho‐physiological approaches to the visualization of spatio‐chromatic data. QCPA combines novel and existing pattern analysis frameworks into what we hope is a unified, free and open source toolbox and introduces a range of novel analytical and data‐visualization approaches. These analyses and tools have been seamlessly integrated into the MICA toolbox providing a dynamic and user‐friendly workflow.
    Type of Medium: Online Resource
    ISSN: 2041-210X , 2041-210X
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2020
    detail.hit.zdb_id: 2528492-7
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  • 4
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2012
    In:  Nature Communications Vol. 3, No. 1 ( 2012-10-09)
    In: Nature Communications, Springer Science and Business Media LLC, Vol. 3, No. 1 ( 2012-10-09)
    Type of Medium: Online Resource
    ISSN: 2041-1723
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2012
    detail.hit.zdb_id: 2553671-0
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  • 5
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2016
    In:  Scientific Reports Vol. 6, No. 1 ( 2016-10-13)
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 6, No. 1 ( 2016-10-13)
    Abstract: It is well-known that features of animal nest architecture can be explained by fitness benefits gained by the offspring housed within. Here we focus on the little-tested suggestion that the fitness costs associated with building and maintaining a nest should additionally account for aspects of its architecture. Burying beetles prepare an edible nest for their young from a small vertebrate carcass, by ripping off any fur or feathers and rolling the flesh into a rounded ball. We found evidence that only larger beetles are able to construct rounder carcass nests, and that rounder carcass nests are associated with lower maintenance costs. Offspring success, however, was not explained by nest roundness. Our experiment thus provides rare support for the suggestion that construction and maintenance costs are key to understanding animal architecture.
    Type of Medium: Online Resource
    ISSN: 2045-2322
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2016
    detail.hit.zdb_id: 2615211-3
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  • 6
    Online Resource
    Online Resource
    The Royal Society ; 2015
    In:  Biology Letters Vol. 11, No. 8 ( 2015-08), p. 20150494-
    In: Biology Letters, The Royal Society, Vol. 11, No. 8 ( 2015-08), p. 20150494-
    Abstract: Camouflage is perhaps the most widespread anti-predator strategy in nature, found in numerous animal groups. A long-standing prediction is that individuals should have camouflage tuned to the visual backgrounds where they live. However, while several studies have demonstrated phenotype–environment associations, few have directly shown that this confers an improvement in camouflage, particularly with respect to predator vision. Here, we show that an intertidal crustacean, the sand flea ( Hippa testudinaria ), has coloration tuned to the different substrates on which it occurs when viewed by potential avian predators. Individual sand fleas from a small, oceanic island (Ascension) matched the colour and luminance of their own beaches more closely than neighbouring beaches to a model of avian vision. Based on past work, this phenotype–environment matching is likely to be driven through ontogenetic changes rather than genetic adaptation. Our work provides some of the first direct evidence that animal coloration is tuned to provide camouflage to prospective predators against a range of visual backgrounds, in a population of animals occurring over a small geographical range.
    Type of Medium: Online Resource
    ISSN: 1744-9561 , 1744-957X
    Language: English
    Publisher: The Royal Society
    Publication Date: 2015
    detail.hit.zdb_id: 2103283-X
    SSG: 12
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  • 7
    Online Resource
    Online Resource
    Wiley ; 2022
    In:  Evolution Vol. 76, No. 5 ( 2022-05), p. 870-882
    In: Evolution, Wiley, Vol. 76, No. 5 ( 2022-05), p. 870-882
    Type of Medium: Online Resource
    ISSN: 0014-3820 , 1558-5646
    URL: Issue
    RVK:
    Language: English
    Publisher: Wiley
    Publication Date: 2022
    detail.hit.zdb_id: 2036375-8
    SSG: 12
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  • 8
    Online Resource
    Online Resource
    The Royal Society ; 2021
    In:  Proceedings of the Royal Society B: Biological Sciences Vol. 288, No. 1942 ( 2021-01-13), p. 20202823-
    In: Proceedings of the Royal Society B: Biological Sciences, The Royal Society, Vol. 288, No. 1942 ( 2021-01-13), p. 20202823-
    Abstract: The motion dazzle hypothesis posits that high contrast geometric patterns can cause difficulties in tracking a moving target and has been argued to explain the patterning of animals such as zebras. Research to date has only tested a small number of patterns, offering equivocal support for the hypothesis. Here, we take a genetic programming approach to allow patterns to evolve based on their fitness (time taken to capture) and thus find the optimal strategy for providing protection when moving. Our ‘Dazzle Bug’ citizen science game tested over 1.5 million targets in a touch screen game at a popular visitor attraction. Surprisingly, we found that targets lost pattern elements during evolution and became closely background matching. Modelling results suggested that targets with lower motion energy were harder to catch. Our results indicate that low contrast, featureless targets offer the greatest protection against capture when in motion, challenging the motion dazzle hypothesis.
    Type of Medium: Online Resource
    ISSN: 0962-8452 , 1471-2954
    Language: English
    Publisher: The Royal Society
    Publication Date: 2021
    detail.hit.zdb_id: 1460975-7
    SSG: 12
    SSG: 25
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  • 9
    In: Current Biology, Elsevier BV, Vol. 30, No. 14 ( 2020-07), p. 2844-2851.e8
    Type of Medium: Online Resource
    ISSN: 0960-9822
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2020
    detail.hit.zdb_id: 2019214-9
    SSG: 12
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  • 10
    In: Behavioral Ecology and Sociobiology, Springer Science and Business Media LLC, Vol. 74, No. 2 ( 2020-02)
    Abstract: In the animal kingdom, conspicuous colors are often used for inter- and intra-sexual communication. Even though primates are the most colorful mammalian taxon, many questions, including what potential information color signals communicate to social partners, are not fully understood. Vervet monkeys ( Chlorocebus pygerythrus ) are ideal to examine the covariates of color signals. Males have multi-colored genitals, which they present during distinctive male-male interactions, known as the “Red-White-and-Blue” (RWB) display, but the genitals are also visible across a variety of other contexts, and it is unclear what this color display signals to recipients. We recorded genital color presentations and standardized digital photos of male genitals ( N  = 405 photos) over one mating season for 20 adult males in three groups at the Samara Private Game Reserve, South Africa. We combined these with data on male characteristics (dominance, age, tenure length, injuries, and fecal glucocorticoid metabolite concentrations). Using visual modeling methods, we measured single colors (red, white, blue) but also the contrasts between colors. We assessed the frequency of the RWB genital display and male variation in genital coloration and linked this to male characteristics. Our data suggest that the number of genital displays increased with male dominance. However, none of the variables investigated explained the inter- and intra-individual variation in male genital coloration. These results suggest that the frequency of the RWB genital display, but not its color value, is related to dominance, providing valuable insights on covariation in color signals and their display in primates. Significance statement Conspicuous colors in animals often communicate individual quality to mates and rivals. By investigating vervet monkeys, a primate species in which males present their colorful genitals within several behavioral displays, we aim to identify the covariates of such colorful signals and their behavioral display. Using visual modeling methods for the color analysis and combining behavioral display data and color data with male characteristics, we found that high-ranking males displayed their colorful genitals more frequently than lower-ranking ones. In contrast, color variation was not influenced by male dominance, age, tenure length, or health. Our results can serve as a basis for future investigations on the function of colorful signals and behavioral displays, such as a badge of status or mate choice in primates.
    Type of Medium: Online Resource
    ISSN: 0340-5443 , 1432-0762
    RVK:
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2020
    detail.hit.zdb_id: 1458476-1
    SSG: 12
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