How plastic is migratory behavior? Quantifying elevational movement in a partially migratory alpine ungulate, the sierra nevada bighorn sheep (ovis canadensis sierrae)

D. B. Spitz, M. Hebblewhite, T. R. Stephenson, D. W. German

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Migratory species face well-documented global declines, but the causes of these declines remain unclear. One obstacle to better understanding these declines is uncertainty surrounding how migratory behavior is maintained. Most migratory populations are partially migratory, displaying both migrant and resident behaviors. Theory only provides two possible explanations for this coexistence of migration and residency: either these behaviors are fixed at the individual level or both behaviors are part of a single conditional strategy in which an individual’s migratory status (adoption of migrant or resident behavior) is plastic. Here we test for plasticity in migratory status and tactics (timing, distance, and duration of migration) in a federally endangered mountain caprid, the Sierra Nevada bighorn sheep (Ovis canadensis sierrae Grinnell, 1912). We used nonlinear modeling to quantitatively describe migratory behavior, analyzing 262 animal-years of GPS location data collected between 2005 and 2016 from 161 females across 14 subpopulations. Migratory tactics and prevalence varied by subpopulation. On average, individuals from partially migratory subpopulations switched migratory status every 4 years. Our results support the hypothesis that partial migration is maintained through a single conditional strategy. Understanding plasticity in migratory behavior will improve monitoring efforts and provide a rigorous basis for evaluating threats, particularly those associated with changing climate.

    Original languageEnglish
    Pages (from-to)1385-1394
    Number of pages10
    JournalCanadian Journal of Zoology
    Volume96
    Issue number12
    DOIs
    StatePublished - 2018

    Keywords

    • Altitudinal migration
    • Behavioral plasticity
    • Caprinae
    • Elevational migration
    • Ovis canadensis sierrae
    • Partial migration
    • Sierra Nevada bighorn sheep

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