Demography and dynamics of three wild horse populations in the Australian Alps

    Research output: Contribution to journalArticle

    19 Citations (Scopus)

    Abstract

    Wild horses (Equus caballus) are a non-native species occupying over 2800 km2 of the nationally significant Australian Alps National Parks.We estimated key demographic parameters (fecundity, adult and juvenile survival and annual finite population growth rate) over 3 years and related these to horse body condition and available food for three populations under natural conditions, and found a trend consistent with food limitation. The populations were independent, with different site characteristics and occupied areas, identified by land managers, as areas of concern about possible conservation impacts. Annual fecundity and juvenile survival varied across sites averaging between 0.21 and 0.31 female young per adult female, and 0.83 and 0.90 per annum, respectively, and annual adult survival was consistent across sites averaging 0.91 per annum. One population was increasing (l = 1.09 year-1;95% CI 1.04â¿¿1.14) and two populationswere stable (l ~ 1.0 year-1).Mean body condition of horses was positively correlated with mean pasture biomass rank.Across the three populations, fecundity, recruitment, body condition and annual finite population growth rate were lowest when mean pasture biomass rank was lowest and conversely highest when pasture rank was highest.We conclude that food limitation appears to be operating across these three sites.We used our results to assess the sensitivity of annual finite rate of increase (l) to changes in key demographic parameters and found that l was most sensitive to a change in adult survival, with the second most sensitive parameter being fecundity.Thus, if the aim of management is to reduce the size of the wild horse population then targeting adult survival is most important, followed by fecundity. Finally, we estimated the linear, negative, numerical response for wild horses between annual l and horses per unit pasture biomass.
    Original languageEnglish
    Pages (from-to)97-109
    Number of pages13
    JournalAustral Ecology
    Volume37
    Issue number1
    DOIs
    Publication statusPublished - 2012

    Fingerprint

    horse
    demography
    fecundity
    horses
    pasture
    body condition
    food limitation
    pastures
    population growth
    biomass
    numerical response
    demographic statistics
    targeting
    national park
    national parks
    managers
    food
    parameter

    Cite this

    @article{70a8a05df3ca446483ee2d1bc0295e31,
    title = "Demography and dynamics of three wild horse populations in the Australian Alps",
    abstract = "Wild horses (Equus caballus) are a non-native species occupying over 2800 km2 of the nationally significant Australian Alps National Parks.We estimated key demographic parameters (fecundity, adult and juvenile survival and annual finite population growth rate) over 3 years and related these to horse body condition and available food for three populations under natural conditions, and found a trend consistent with food limitation. The populations were independent, with different site characteristics and occupied areas, identified by land managers, as areas of concern about possible conservation impacts. Annual fecundity and juvenile survival varied across sites averaging between 0.21 and 0.31 female young per adult female, and 0.83 and 0.90 per annum, respectively, and annual adult survival was consistent across sites averaging 0.91 per annum. One population was increasing (l = 1.09 year-1;95{\%} CI 1.04{\^a}¿¿1.14) and two populationswere stable (l ~ 1.0 year-1).Mean body condition of horses was positively correlated with mean pasture biomass rank.Across the three populations, fecundity, recruitment, body condition and annual finite population growth rate were lowest when mean pasture biomass rank was lowest and conversely highest when pasture rank was highest.We conclude that food limitation appears to be operating across these three sites.We used our results to assess the sensitivity of annual finite rate of increase (l) to changes in key demographic parameters and found that l was most sensitive to a change in adult survival, with the second most sensitive parameter being fecundity.Thus, if the aim of management is to reduce the size of the wild horse population then targeting adult survival is most important, followed by fecundity. Finally, we estimated the linear, negative, numerical response for wild horses between annual l and horses per unit pasture biomass.",
    keywords = "demographic rate, Equus caballus, feral horse, numerical response, population growth rate, wild horse.",
    author = "Jim Hone",
    year = "2012",
    doi = "10.1111/j.1442-9993.2011.02247.x",
    language = "English",
    volume = "37",
    pages = "97--109",
    journal = "Austral Ecology",
    issn = "1442-9985",
    publisher = "Wiley-Blackwell",
    number = "1",

    }

    Demography and dynamics of three wild horse populations in the Australian Alps. / Hone, Jim.

    In: Austral Ecology, Vol. 37, No. 1, 2012, p. 97-109.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - Demography and dynamics of three wild horse populations in the Australian Alps

    AU - Hone, Jim

    PY - 2012

    Y1 - 2012

    N2 - Wild horses (Equus caballus) are a non-native species occupying over 2800 km2 of the nationally significant Australian Alps National Parks.We estimated key demographic parameters (fecundity, adult and juvenile survival and annual finite population growth rate) over 3 years and related these to horse body condition and available food for three populations under natural conditions, and found a trend consistent with food limitation. The populations were independent, with different site characteristics and occupied areas, identified by land managers, as areas of concern about possible conservation impacts. Annual fecundity and juvenile survival varied across sites averaging between 0.21 and 0.31 female young per adult female, and 0.83 and 0.90 per annum, respectively, and annual adult survival was consistent across sites averaging 0.91 per annum. One population was increasing (l = 1.09 year-1;95% CI 1.04â¿¿1.14) and two populationswere stable (l ~ 1.0 year-1).Mean body condition of horses was positively correlated with mean pasture biomass rank.Across the three populations, fecundity, recruitment, body condition and annual finite population growth rate were lowest when mean pasture biomass rank was lowest and conversely highest when pasture rank was highest.We conclude that food limitation appears to be operating across these three sites.We used our results to assess the sensitivity of annual finite rate of increase (l) to changes in key demographic parameters and found that l was most sensitive to a change in adult survival, with the second most sensitive parameter being fecundity.Thus, if the aim of management is to reduce the size of the wild horse population then targeting adult survival is most important, followed by fecundity. Finally, we estimated the linear, negative, numerical response for wild horses between annual l and horses per unit pasture biomass.

    AB - Wild horses (Equus caballus) are a non-native species occupying over 2800 km2 of the nationally significant Australian Alps National Parks.We estimated key demographic parameters (fecundity, adult and juvenile survival and annual finite population growth rate) over 3 years and related these to horse body condition and available food for three populations under natural conditions, and found a trend consistent with food limitation. The populations were independent, with different site characteristics and occupied areas, identified by land managers, as areas of concern about possible conservation impacts. Annual fecundity and juvenile survival varied across sites averaging between 0.21 and 0.31 female young per adult female, and 0.83 and 0.90 per annum, respectively, and annual adult survival was consistent across sites averaging 0.91 per annum. One population was increasing (l = 1.09 year-1;95% CI 1.04â¿¿1.14) and two populationswere stable (l ~ 1.0 year-1).Mean body condition of horses was positively correlated with mean pasture biomass rank.Across the three populations, fecundity, recruitment, body condition and annual finite population growth rate were lowest when mean pasture biomass rank was lowest and conversely highest when pasture rank was highest.We conclude that food limitation appears to be operating across these three sites.We used our results to assess the sensitivity of annual finite rate of increase (l) to changes in key demographic parameters and found that l was most sensitive to a change in adult survival, with the second most sensitive parameter being fecundity.Thus, if the aim of management is to reduce the size of the wild horse population then targeting adult survival is most important, followed by fecundity. Finally, we estimated the linear, negative, numerical response for wild horses between annual l and horses per unit pasture biomass.

    KW - demographic rate

    KW - Equus caballus

    KW - feral horse

    KW - numerical response

    KW - population growth rate

    KW - wild horse.

    U2 - 10.1111/j.1442-9993.2011.02247.x

    DO - 10.1111/j.1442-9993.2011.02247.x

    M3 - Article

    VL - 37

    SP - 97

    EP - 109

    JO - Austral Ecology

    JF - Austral Ecology

    SN - 1442-9985

    IS - 1

    ER -