How landscape dynamics link individual- to population-level movement patterns: a multispecies comparison of ungulate relocation data

Authors

  • Thomas Mueller,

    Corresponding author
    1. Department of Biology, University of Maryland, College Park, MD 20742, USA
    2. Smithsonian Conservation Biology Institute, National Zoological Park, 1500 Remount Road, Front Royal, VA 22630, USA
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  • Kirk A. Olson,

    1. Department of Environmental Conservation, University of Massachusetts, Amherst, MA 01003-9285, USA
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  • Gunnar Dressler,

    1. Department of Biology, University of Maryland, College Park, MD 20742, USA
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    • Present address: University of Greifswald, Department of Mathematics and Computer Science, Robert-Blum-Strasse 2, D-17487 Greifswald, Germany.

  • Peter Leimgruber,

    1. Smithsonian Conservation Biology Institute, National Zoological Park, 1500 Remount Road, Front Royal, VA 22630, USA
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  • Todd K. Fuller,

    1. Department of Environmental Conservation, University of Massachusetts, Amherst, MA 01003-9285, USA
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  • Craig Nicolson,

    1. Department of Environmental Conservation, University of Massachusetts, Amherst, MA 01003-9285, USA
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  • Andres J. Novaro,

    1. Argentine Research Council and Patagonian and Andean Steppe Program-Wildlife Conservation Society, Carilafquen 51, Junin de los Andes, 8371 Neuquén, Argentina
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  • Maria J. Bolgeri,

    1. Argentine Science Agency and Patagonian and Andean Steppe Program-Wildlife Conservation Society, Carilafquen 51, Junin de los Andes, 8371 Neuquén, Argentina
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  • David Wattles,

    1. US Geological Survey, Massachusetts Cooperative Fish and Wildlife Research Unit, University of Massachusetts, Amherst, MA 01003, USA
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  • Stephen DeStefano,

    1. US Geological Survey, Massachusetts Cooperative Fish and Wildlife Research Unit, University of Massachusetts, Amherst, MA 01003, USA
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  • Justin M. Calabrese,

    1. Smithsonian Conservation Biology Institute, National Zoological Park, 1500 Remount Road, Front Royal, VA 22630, USA
    2. Department of Ecological Modelling, Helmholtz Centre for Environmental Research-UFZ, Permoserstrasse 15, 04318 Leipzig, Germany
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  • William F. Fagan

    1. Department of Biology, University of Maryland, College Park, MD 20742, USA
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Thomas Mueller, Department of Biology, BioPsych-Building, Room 3205, University of Maryland, College Park, MD 20742, USA. E-mail: muellert@gmail.com

ABSTRACT

Aim  To demonstrate how the interrelations of individual movements form large-scale population-level movement patterns and how these patterns are associated with the underlying landscape dynamics by comparing ungulate movements across species.

Locations  Arctic tundra in Alaska and Canada, temperate forests in Massachusetts, Patagonian Steppes in Argentina, Eastern Steppes in Mongolia.

Methods  We used relocation data from four ungulate species (barren-ground caribou, Mongolian gazelle, guanaco and moose) to examine individual movements and the interrelation of movements among individuals. We applied and developed a suite of spatial metrics that measure variation in movement among individuals as population dispersion, movement coordination and realized mobility. Taken together, these metrics allowed us to quantify and distinguish among different large-scale population-level movement patterns such as migration, range residency and nomadism. We then related the population-level movement patterns to the underlying landscape vegetation dynamics via long-term remote sensing measurements of the temporal variability, spatial variability and unpredictability of vegetation productivity.

Results  Moose, which remained in sedentary home ranges, and guanacos, which were partially migratory, exhibited relatively short annual movements associated with landscapes having very little broad-scale variability in vegetation. Caribou and gazelle performed extreme long-distance movements that were associated with broad-scale variability in vegetation productivity during the peak of the growing season. Caribou exhibited regular seasonal migration in which individuals were clustered for most of the year and exhibited coordinated movements. In contrast, gazelle were nomadic, as individuals were independently distributed and moved in an uncoordinated manner that relates to the comparatively unpredictable (yet broad-scale) vegetation dynamics of their landscape.

Main conclusions  We show how broad-scale landscape unpredictability may lead to nomadism, an understudied type of long-distance movement. In contrast to classical migration where landscapes may vary at broad scales but in a predictable manner, long-distance movements of nomadic individuals are uncoordinated and independent from other such individuals. Landscapes with little broad-scale variability in vegetation productivity feature smaller-scale movements and allow for range residency. Nomadism requires distinct integrative conservation strategies that facilitate long-distance movements across the entire landscape and are not limited to certain migration corridors.

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