Biodiversity and Conservation

, Volume 28, Issue 14, pp 3803–3830 | Cite as

Transition to density dependence in a reintroduced ecosystem engineer

  • Adrian D. ManningEmail author
  • Maldwyn J. Evans
  • Sam C. Banks
  • William G. Batson
  • Emily Belton
  • Helen A. Crisp
  • Donald B. Fletcher
  • Iain J. Gordon
  • Kate Grarock
  • Nicki Munro
  • Jenny Newport
  • Jennifer Pierson
  • Timothy J. Portas
  • Melissa A. Snape
  • Claire Wimpenny
Original Paper


When does a reintroduced population of animals become self-regulating? Quantifying this is critical in determining when interventions can be tapered off, or when they may need to be reinstated. We tracked the growth trajectory of a reintroduced population to establish whether it was irruptive and/or had transitioned to self-regulation. In 2012, we reintroduced 32 eastern bettongs (Bettongia gaimardi), a potoroid marsupial from Tasmania, Australia, to a 485 ha exotic predator-proof fenced reserve in the Australian Capital Territory. We established a 92 cage trap monitoring network to track population growth between the Austral Autumn 2014 and Summer 2018. We used capture-recapture models to track changes in the population through time, and modelled ‘bettong weight’, ‘pouch occupancy’ and ‘age of pouch young’ with population variation, to establish potential associations with changes in population size. The estimated population grew from 32 individuals in 2012 to 100 in 2014, 192 in Autumn 2016, and then declined to 151 in Summer 2018. Estimated survival of adults was high—above 92% between most sessions. Adult female weights ranged between 0.485 and 2.428 kg, and adult males between 0.470 and 2.775 kg. Our study showed density dependence was achieved over the 6 year period. Low adult mortality, and variable pouch occupancy related to female weight, suggested that food availability had influenced lactation in females, with flow-on impacts on juvenile survival. Long-term, broad-scale population dynamics were probably driven by a mix of direct (e.g. disease, harvesting for other reintroductions), and indirect (i.e. climate dependent availability of nutritious food) influences on population size.


Australia Bettongia gaimardi Density dependence Marsupial Reintroduction Self-regulation 



The translocation was carried out under license from the Tasmanian Department of Primary Industries, Parks, Water and Environment (DPIPWE) using procedures approved by their associated Ethics Committee (AEC Project 18/2010–2011). We thank DPIPWE for their support. The post-reintroduction procedures were approved by the Australian National University Animal Experimentation Ethics Committee (ethics protocol A2011/017; A2017/33). WB was supported by a Ph.D. scholarship funded through an Australian Research Council Linkage Grant (LP110100126). ADM was supported by an Australian Research Council Future Fellowship (FT100100358) during part of this study. This project was conducted as part of the Mulligans Flat–Goorooyarroo Woodland Experiment. Thanks to all the staff and volunteers that assisted with the bettong trapping. We also thank Ross Cunningham, David Dobroszczyk, Elyce Fraser, Daniel Iglesias, Stuart Jeffress, Chris Johnson, Margaret Kitchin, Ani Kunz, John Lawler, Peter Mills, Nick Mooney, Matthew Pauza, Andrea Reiss, Scott Ryan, David Shorthouse, Georgeanna Story, Jeff Wood, Grant Woodbridge and Tingbao Xu for their assistance during the project.

Compliance with ethical standards

Conflict of interest

We declare that there are no conflict of interest.


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Copyright information

© Springer Nature B.V. 2019

Authors and Affiliations

  • Adrian D. Manning
    • 1
    Email author
  • Maldwyn J. Evans
    • 1
  • Sam C. Banks
    • 2
  • William G. Batson
    • 3
    • 4
  • Emily Belton
    • 4
  • Helen A. Crisp
    • 5
  • Donald B. Fletcher
    • 1
  • Iain J. Gordon
    • 1
    • 6
    • 7
  • Kate Grarock
    • 4
  • Nicki Munro
    • 1
  • Jenny Newport
    • 1
  • Jennifer Pierson
    • 8
  • Timothy J. Portas
    • 9
  • Melissa A. Snape
    • 10
  • Claire Wimpenny
    • 10
  1. 1.The Fenner School of Environment and SocietyThe Australian National UniversityCanberraAustralia
  2. 2.Research Institute for the Environment and LivelihoodsCharles Darwin UniversityDarwinAustralia
  3. 3.ACT Parks and Conservation ServiceMitchellAustralia
  4. 4.Woodlands and Wetlands TrustFordeAustralia
  5. 5.The Australian Wildlife ConservancyYookamurra Wildlife SanctuaryFisherAustralia
  6. 6.Division of Tropical Environments and SocietiesJames Cook University TownsvilleDouglasAustralia
  7. 7.James Hutton InstituteAberdeenUK
  8. 8.ACT Parks and Conservation ServiceTidbinbilla Nature ReservePaddys RiverAustralia
  9. 9.Timothy Portas, Zoo & Wildlife Veterinary ConsultancyNorth MalenyAustralia
  10. 10.Conservation Research; Environment, Planning and Sustainable Development Directorate, ACT GovernmentCanberraAustralia

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