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    Data from: Abundance and population growth estimates for bare-nosed wombats

    • data.niaid.nih.gov
    • datadryad.org
    zip
    Updated Aug 25, 2023
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    Wiebke Knoblauch; Scott Carver; Michael Driessen; Rosemary Gales; Shane Richards (2023). Abundance and population growth estimates for bare-nosed wombats [Dataset]. http://doi.org/10.5061/dryad.q83bk3jnz
    Explore at:
    zipAvailable download formats
    Dataset updated
    Aug 25, 2023
    Dataset provided by
    University of Tasmania
    Department of Natural Resources and Environment, Tasmania
    Authors
    Wiebke Knoblauch; Scott Carver; Michael Driessen; Rosemary Gales; Shane Richards
    License

    https://spdx.org/licenses/CC0-1.0.htmlhttps://spdx.org/licenses/CC0-1.0.html

    Description

    Wildlife managers often rely on population estimates, but estimates can be challenging to obtain for geographically widespread species. Spotlight surveys provide abundance data for many species and, when conducted over wide spatial scales, have the potential to provide population estimates of geographically widespread species. The bare-nosed wombat (Vombatus ursinus) has a broad geographic range and is subject to spotlight surveys. We used 19 years (2002–2020) of annual spotlight surveys to provide the first estimates of population abundance for two of the three extant bare-nosed wombat subspecies: V. u. ursinus on Flinders Island; and V. u. tasmaniensis on the Tasmanian mainland. Using distance sampling methods, we estimated annual rates of change and 2020 population sizes for both sub-species. Tasmanian mainland surveys included habitat data, which allowed us to also look for evidence of habitat associations for V. u. tasmaniensis. The average wombat density estimate was higher on Flinders Island (0.42 ha-1, 95% CrI = 0.25 – 0.79) than on the Tasmanian mainland (0.11 ha-1, CrI = 0.07 – 0.19) and both wombat subspecies increased over the 19-year survey period with an estimated annual growth rate of 2.90% (CrI = -1.7 – 7.3) on Flinders Island and 1.20% (CrI = -1.1 – 2.9) on mainland Tasmania. Habitat associations for V. u. tasmaniensis were weak, possibly owing to survey design; however, we detected regional variation in density for this subspecies. We estimated the population size of V. u. ursinus to be 71,826 (CrI = 43,913 – 136,761) on Flinders Island, which when combined with a previously published estimate of 2,599 (CI = 2,254 – 2,858) from Maria Island, where the subspecies was introduced, provides a total population estimate. We also estimated 840,665 (CrI = 531,104 – 1,201,547) V. u. tasmaniensis on mainland Tasmania. These estimates may be conservative, owing to individual heterogeneity in when wombats emerge from burrows. Although these two sub-species are not currently threatened, our population estimates provide an important reference when assessing their population status in the future, and demonstrate how spotlight surveys can be valuable to inform management of geographically widespread species.

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Share
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TwitterTwitter
Email
Click to copy link
Link copied
Close
Cite
Wiebke Knoblauch; Scott Carver; Michael Driessen; Rosemary Gales; Shane Richards (2023). Abundance and population growth estimates for bare-nosed wombats [Dataset]. http://doi.org/10.5061/dryad.q83bk3jnz

Data from: Abundance and population growth estimates for bare-nosed wombats

Related Article
Explore at:
zipAvailable download formats
Dataset updated
Aug 25, 2023
Dataset provided by
University of Tasmania
Department of Natural Resources and Environment, Tasmania
Authors
Wiebke Knoblauch; Scott Carver; Michael Driessen; Rosemary Gales; Shane Richards
License

https://spdx.org/licenses/CC0-1.0.htmlhttps://spdx.org/licenses/CC0-1.0.html

Description

Wildlife managers often rely on population estimates, but estimates can be challenging to obtain for geographically widespread species. Spotlight surveys provide abundance data for many species and, when conducted over wide spatial scales, have the potential to provide population estimates of geographically widespread species. The bare-nosed wombat (Vombatus ursinus) has a broad geographic range and is subject to spotlight surveys. We used 19 years (2002–2020) of annual spotlight surveys to provide the first estimates of population abundance for two of the three extant bare-nosed wombat subspecies: V. u. ursinus on Flinders Island; and V. u. tasmaniensis on the Tasmanian mainland. Using distance sampling methods, we estimated annual rates of change and 2020 population sizes for both sub-species. Tasmanian mainland surveys included habitat data, which allowed us to also look for evidence of habitat associations for V. u. tasmaniensis. The average wombat density estimate was higher on Flinders Island (0.42 ha-1, 95% CrI = 0.25 – 0.79) than on the Tasmanian mainland (0.11 ha-1, CrI = 0.07 – 0.19) and both wombat subspecies increased over the 19-year survey period with an estimated annual growth rate of 2.90% (CrI = -1.7 – 7.3) on Flinders Island and 1.20% (CrI = -1.1 – 2.9) on mainland Tasmania. Habitat associations for V. u. tasmaniensis were weak, possibly owing to survey design; however, we detected regional variation in density for this subspecies. We estimated the population size of V. u. ursinus to be 71,826 (CrI = 43,913 – 136,761) on Flinders Island, which when combined with a previously published estimate of 2,599 (CI = 2,254 – 2,858) from Maria Island, where the subspecies was introduced, provides a total population estimate. We also estimated 840,665 (CrI = 531,104 – 1,201,547) V. u. tasmaniensis on mainland Tasmania. These estimates may be conservative, owing to individual heterogeneity in when wombats emerge from burrows. Although these two sub-species are not currently threatened, our population estimates provide an important reference when assessing their population status in the future, and demonstrate how spotlight surveys can be valuable to inform management of geographically widespread species.

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