Accuracy of identifications of mammal species from camera trap images: A northern Australian case study

Larissa C. Potter, Christopher J. Brady, Brett P. Murphy

    Research output: Contribution to journalArticleResearchpeer-review

    Abstract

    Camera traps are a powerful and increasingly popular tool for mammal research, but like all survey methods, they have limitations. Identifying animal species from images is a critical component of camera trap studies, yet while researchers recognize constraints with experimental design or camera technology, image misidentification is still not well understood. We evaluated the effects of a species’ attributes (body mass and distinctiveness) and individual observer variables (experience and confidence) on the accuracy of mammal identifications from camera trap images. We conducted an Internet-based survey containing 20 questions about observer experience and 60 camera trap images to identify. Images were sourced from surveys in northern Australia and included 25 species, ranging in body mass from the delicate mouse (Pseudomys delicatulus, 10 g) to the agile wallaby (Macropus agilis, >10 kg). There was a weak relationship between the accuracy of mammal identifications and observer experience. However, accuracy was highest (100%) for distinctive species (e.g. Short-beaked echidna [Tachyglossus aculeatus]) and lowest (36%) for superficially non-distinctive mammals (e.g. rodents like the Pale field-rat [Rattus tunneyi]). There was a positive relationship between the accuracy of identifications and body mass. Participant confidence was highest for large and distinctive mammals, but was not related to participant experience level. Identifications made with greater confidence were more likely to be accurate. Unreliability in identifications of mammal species is a significant limitation to camera trap studies, particularly where small mammals are the focus, or where similar-looking species co-occur. Integration of camera traps with conventional survey techniques (e.g. live-trapping), use of a reference library or computer-automated programs are likely to aid positive identifications, while employing a confidence rating system and/or multiple observers may lead to a collection of more robust data. Although our study focussed on Australian species, our findings apply to camera trap studies globally.

    LanguageEnglish
    Number of pages11
    JournalAustral Ecology
    Early online date23 Nov 2018
    DOIs
    Publication statusE-pub ahead of print - 23 Nov 2018

    Fingerprint

    cameras
    mammal
    traps
    mammals
    case studies
    body mass
    Macropus agilis
    survey method
    Tachyglossidae
    small mammal
    experimental design
    Rattus
    rodent
    trapping
    small mammals
    software
    rodents
    researchers
    rats
    mice

    Cite this

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    title = "Accuracy of identifications of mammal species from camera trap images: A northern Australian case study",
    abstract = "Camera traps are a powerful and increasingly popular tool for mammal research, but like all survey methods, they have limitations. Identifying animal species from images is a critical component of camera trap studies, yet while researchers recognize constraints with experimental design or camera technology, image misidentification is still not well understood. We evaluated the effects of a species’ attributes (body mass and distinctiveness) and individual observer variables (experience and confidence) on the accuracy of mammal identifications from camera trap images. We conducted an Internet-based survey containing 20 questions about observer experience and 60 camera trap images to identify. Images were sourced from surveys in northern Australia and included 25 species, ranging in body mass from the delicate mouse (Pseudomys delicatulus, 10 g) to the agile wallaby (Macropus agilis, >10 kg). There was a weak relationship between the accuracy of mammal identifications and observer experience. However, accuracy was highest (100{\%}) for distinctive species (e.g. Short-beaked echidna [Tachyglossus aculeatus]) and lowest (36{\%}) for superficially non-distinctive mammals (e.g. rodents like the Pale field-rat [Rattus tunneyi]). There was a positive relationship between the accuracy of identifications and body mass. Participant confidence was highest for large and distinctive mammals, but was not related to participant experience level. Identifications made with greater confidence were more likely to be accurate. Unreliability in identifications of mammal species is a significant limitation to camera trap studies, particularly where small mammals are the focus, or where similar-looking species co-occur. Integration of camera traps with conventional survey techniques (e.g. live-trapping), use of a reference library or computer-automated programs are likely to aid positive identifications, while employing a confidence rating system and/or multiple observers may lead to a collection of more robust data. Although our study focussed on Australian species, our findings apply to camera trap studies globally.",
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    Accuracy of identifications of mammal species from camera trap images : A northern Australian case study. / Potter, Larissa C.; Brady, Christopher J.; Murphy, Brett P.

    In: Austral Ecology, 23.11.2018.

    Research output: Contribution to journalArticleResearchpeer-review

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