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Abundance and population growth estimates for bare‐nosed wombats

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 potential to provide population estimates of geographic...

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Autores principales: Knoblauch, Wiebke, Carver, Scott, Driessen, Michael M., Gales, Rosemary, Richards, Shane A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10477484/
https://www.ncbi.nlm.nih.gov/pubmed/37674647
http://dx.doi.org/10.1002/ece3.10465
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author Knoblauch, Wiebke
Carver, Scott
Driessen, Michael M.
Gales, Rosemary
Richards, Shane A.
author_facet Knoblauch, Wiebke
Carver, Scott
Driessen, Michael M.
Gales, Rosemary
Richards, Shane A.
author_sort Knoblauch, Wiebke
collection PubMed
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 potential to provide population estimates of geographically widespread species. The bare‐nosed wombat (Vombatus ursinus) has a broad geographical 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 subspecies. 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% CI = 0.25–0.79) than on the Tasmanian mainland (0.11 ha(−1), CI = 0.07–0.19) and both wombat subspecies increased over the 19‐year survey period with an estimated annual growth rate of 2.90% (CI = −1.7 to 7.3) on Flinders Island and 1.20% (CI = −1.1 to 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 (CI = 43,913–136,761) on Flinders Island, which when combined with a previously published estimate of 2599 (CI = 2254–2858) from Maria Island, where the subspecies was introduced, provides a total population estimate. We also estimated 840,665 (CI = 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 subspecies 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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spelling pubmed-104774842023-09-06 Abundance and population growth estimates for bare‐nosed wombats Knoblauch, Wiebke Carver, Scott Driessen, Michael M. Gales, Rosemary Richards, Shane A. Ecol Evol Research Articles 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 potential to provide population estimates of geographically widespread species. The bare‐nosed wombat (Vombatus ursinus) has a broad geographical 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 subspecies. 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% CI = 0.25–0.79) than on the Tasmanian mainland (0.11 ha(−1), CI = 0.07–0.19) and both wombat subspecies increased over the 19‐year survey period with an estimated annual growth rate of 2.90% (CI = −1.7 to 7.3) on Flinders Island and 1.20% (CI = −1.1 to 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 (CI = 43,913–136,761) on Flinders Island, which when combined with a previously published estimate of 2599 (CI = 2254–2858) from Maria Island, where the subspecies was introduced, provides a total population estimate. We also estimated 840,665 (CI = 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 subspecies 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. John Wiley and Sons Inc. 2023-09-04 /pmc/articles/PMC10477484/ /pubmed/37674647 http://dx.doi.org/10.1002/ece3.10465 Text en © 2023 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd. https://creativecommons.org/licenses/by/4.0/This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research Articles
Knoblauch, Wiebke
Carver, Scott
Driessen, Michael M.
Gales, Rosemary
Richards, Shane A.
Abundance and population growth estimates for bare‐nosed wombats
title Abundance and population growth estimates for bare‐nosed wombats
title_full Abundance and population growth estimates for bare‐nosed wombats
title_fullStr Abundance and population growth estimates for bare‐nosed wombats
title_full_unstemmed Abundance and population growth estimates for bare‐nosed wombats
title_short Abundance and population growth estimates for bare‐nosed wombats
title_sort abundance and population growth estimates for bare‐nosed wombats
topic Research Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10477484/
https://www.ncbi.nlm.nih.gov/pubmed/37674647
http://dx.doi.org/10.1002/ece3.10465
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