Annual Pronghorn Survival of a Partially Migratory Population

Paul F. Jones, Andrew F. Jakes, Daniel R. Eacker, Mark Hebblewhite

    Research output: Contribution to journalArticlepeer-review

    Abstract

    The importance of conserving migratory populations is recognized across a variety of ungulate taxa, yet the demographic benefits of migration remain uncertain for ungulate populations that exhibit partial migration. We hypothesized that migratory pronghorn (Antilocapra americana) would experience greater survival compared to residents by moving longer distances to avoid severe winter weather and access higher quality forage. We used a Bayesian time-to-event approach to analyze the fates of 175 radio-collared adult female pronghorn monitored over 8 biological years (2004–2011) in the Northern Sagebrush Steppe ecosystem. Annual survivorship of migratory pronghorn was 7% higher on average compared to residents but not statistically different. Migratory pronghorn had higher survivorship in summer and winter compared to residents, and few mortalities were observed during the short autumn and spring migration periods. Mortality risk for both movement tactics intensified under more severe winter weather; winter weather severity alone best explained annual pronghorn mortality risk. The top model predicted survival rates to decline on average by 56% over the range of observed winter climatic conditions. To minimize human impacts to pronghorn during extreme climatic events, we recommend working with transportation departments and land managers to enhance pronghorn crossings of roads and railroads, and landholders to modify fences to wildlife-friendly standards.

    Original languageEnglish
    Pages (from-to)1114-1126
    Number of pages13
    JournalJournal of Wildlife Management
    Volume84
    Issue number6
    DOIs
    StatePublished - Aug 1 2020

    Keywords

    • adult female survival
    • Alberta
    • Antilocapra americana
    • Bayesian
    • Montana
    • movement tactics
    • pronghorn
    • Saskatchewan
    • winter severity

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