Episodic outbreaks of small mammals infl uence predator community dynamics in an east African savanna ecosystem

Andrea Byrom, Meggan Craft, Sarah Durant, Ally Nkwabi, Kristine Metzger, Katie Hampson, Simon Mduma, Guy Forrester, Wendy RUSCOE, Denne Reed, John Bukombe, John Mchetto, A Sinclair

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    12 Citations (Scopus)

    Abstract

    Little is known about the dynamics of small mammals in tropical savanna: a critical gap in our understanding of Africa's best known ecosystems. Historical evidence suggested small mammals peak in abundance (outbreak) in Serengeti National Park (SNP), as in agricultural systems. We asked 1) what are bottom – up drivers of small mammals and 2) do predators have top – down effects? We documented dynamics of small mammals, birds of prey, and mammalian carnivores in SNP and agricultural areas. We used climatic fluctuations and differences between unmodified and agricultural systems as perturbations to examine trophic processes, key to understanding responses to climate change and increasing human pressures. Data were derived from intermittent measures of abundance collected 1968 – 1999, combined with systematic sampling 2000 – 2010 to construct a 42-year time series. Data on abundance of black-shouldered kites (1968 – 2010), eight other species of rodent-eating birds (1997 – 2010), and 10 carnivore species (1993 – 2010) were also collated. Outbreaks occurred every 3 – 5 years in SNP, with low or zero abundance between peaks. There was a positive relationship between rainfall in the wet season and 1) small mammal abundance and 2) the probability of an outbreak, both of which increased with negative Southern Oscillation Index values. Rodent-eating birds and carnivores peaked 6 – 12 months after small mammals. In agricultural areas, abundance remained higher than in natural habitats. Abundances of birds of prey and mammalian carnivores were extremely low in these areas and not related to small mammal abundance. Small mammals are an important food resource for higher trophic levels in the Serengeti ecosystem. Changes in climate and land use may alter their future dynamics, with cascading consequences for higher trophic levels, including threatened carnivores. Although outbreaks cause substantial damage to crops in agricultural areas, small mammals also play a vital role in maintaining some of the diversity and complexity found in African savanna ecosystems.
    Original languageEnglish
    Pages (from-to)1014-1024
    Number of pages11
    JournalOikos (Malden)
    Volume123
    Issue number8
    DOIs
    Publication statusPublished - 2014

    Fingerprint

    community dynamics
    small mammal
    small mammals
    savanna
    savannas
    predator
    predators
    ecosystems
    ecosystem
    carnivore
    carnivores
    national parks
    national park
    agricultural land
    birds of prey
    farming system
    trophic level
    rodent
    rodents
    ingestion

    Cite this

    Byrom, A., Craft, M., Durant, S., Nkwabi, A., Metzger, K., Hampson, K., ... Sinclair, A. (2014). Episodic outbreaks of small mammals infl uence predator community dynamics in an east African savanna ecosystem. Oikos (Malden), 123(8), 1014-1024. https://doi.org/10.1111/oik.00962
    Byrom, Andrea ; Craft, Meggan ; Durant, Sarah ; Nkwabi, Ally ; Metzger, Kristine ; Hampson, Katie ; Mduma, Simon ; Forrester, Guy ; RUSCOE, Wendy ; Reed, Denne ; Bukombe, John ; Mchetto, John ; Sinclair, A. / Episodic outbreaks of small mammals infl uence predator community dynamics in an east African savanna ecosystem. In: Oikos (Malden). 2014 ; Vol. 123, No. 8. pp. 1014-1024.
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    abstract = "Little is known about the dynamics of small mammals in tropical savanna: a critical gap in our understanding of Africa's best known ecosystems. Historical evidence suggested small mammals peak in abundance (outbreak) in Serengeti National Park (SNP), as in agricultural systems. We asked 1) what are bottom – up drivers of small mammals and 2) do predators have top – down effects? We documented dynamics of small mammals, birds of prey, and mammalian carnivores in SNP and agricultural areas. We used climatic fluctuations and differences between unmodified and agricultural systems as perturbations to examine trophic processes, key to understanding responses to climate change and increasing human pressures. Data were derived from intermittent measures of abundance collected 1968 – 1999, combined with systematic sampling 2000 – 2010 to construct a 42-year time series. Data on abundance of black-shouldered kites (1968 – 2010), eight other species of rodent-eating birds (1997 – 2010), and 10 carnivore species (1993 – 2010) were also collated. Outbreaks occurred every 3 – 5 years in SNP, with low or zero abundance between peaks. There was a positive relationship between rainfall in the wet season and 1) small mammal abundance and 2) the probability of an outbreak, both of which increased with negative Southern Oscillation Index values. Rodent-eating birds and carnivores peaked 6 – 12 months after small mammals. In agricultural areas, abundance remained higher than in natural habitats. Abundances of birds of prey and mammalian carnivores were extremely low in these areas and not related to small mammal abundance. Small mammals are an important food resource for higher trophic levels in the Serengeti ecosystem. Changes in climate and land use may alter their future dynamics, with cascading consequences for higher trophic levels, including threatened carnivores. Although outbreaks cause substantial damage to crops in agricultural areas, small mammals also play a vital role in maintaining some of the diversity and complexity found in African savanna ecosystems.",
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    Byrom, A, Craft, M, Durant, S, Nkwabi, A, Metzger, K, Hampson, K, Mduma, S, Forrester, G, RUSCOE, W, Reed, D, Bukombe, J, Mchetto, J & Sinclair, A 2014, 'Episodic outbreaks of small mammals infl uence predator community dynamics in an east African savanna ecosystem', Oikos (Malden), vol. 123, no. 8, pp. 1014-1024. https://doi.org/10.1111/oik.00962

    Episodic outbreaks of small mammals infl uence predator community dynamics in an east African savanna ecosystem. / Byrom, Andrea; Craft, Meggan; Durant, Sarah; Nkwabi, Ally; Metzger, Kristine; Hampson, Katie; Mduma, Simon; Forrester, Guy; RUSCOE, Wendy; Reed, Denne; Bukombe, John; Mchetto, John; Sinclair, A.

    In: Oikos (Malden), Vol. 123, No. 8, 2014, p. 1014-1024.

    Research output: Contribution to journalArticle

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