Vigilance and grouping in the southern African ground squirrel (Xerus inauris)

    Authors

    S. Edwards;J. M. Waterman

    Comments

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    Abbreviated Journal Title

    Afr. J. Ecol.

    Keywords

    Cape ground squirrels; foraging-vigilance trade-off; grouping; vigilance; DEGUS OCTODON-DEGUS; GROUP-SIZE; COLLECTIVE VIGILANCE; ANTIPREDATOR; VIGILANCE; PREDATION RISK; BEHAVIOR; INCREASES; SCIURIDAE; PATTERNS; RODENTIA; Ecology

    Abstract

    Animals may form groups in response to the foraging-vigilance trade-off, through enhanced predator detection (collective detection hypothesis) or reduced predation risk to the individual (dilution hypothesis), allowing individuals to decrease vigilance levels. Both hypotheses predict decreasing individual vigilance levels with increasing group size; however, the collective detection hypothesis also predicts increasing overall group vigilance with increasing group size. However, in species in which vigilance and foraging are not mutually exclusive, where vigilance may not be as costly, neither of these hypotheses may apply. Here, we examine the relationship between group size and vigilance in the social Cape ground squirrel (Xerus inauris), a species that can combine foraging and vigilance behaviours. Ten groups were observed using scan sampling, measuring both group and individual vigilance and group size. A negative relationship existed between individual vigilance and group size and a positive relationship between group vigilance and group size. Therefore, in Cape ground squirrels, vigilance seems to be costly even though it can be combined with foraging behaviours. Furthermore, group vigilance behaviour gives support to the collective detection hypothesis, whilst individual vigilance gives support to both hypotheses.

    Journal Title

    African Journal of Ecology

    Volume

    49

    Issue/Number

    3

    Publication Date

    1-1-2011

    Document Type

    Article

    Language

    English

    First Page

    286

    Last Page

    291

    WOS Identifier

    WOS:000293516000004

    ISSN

    0141-6707

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