Wildlife Research Wildlife Research Society
Ecology, management and conservation in natural and modified habitats
RESEARCH ARTICLE

Estimating site occupancy and detectability of an endangered New Zealand lizard, the Otago skink (Oligosoma otagense)

Catherine M. Roughton A and Philip J. Seddon B C
+ Author Affiliations
- Author Affiliations

A 32B Huria Lane, Woodend, North Canterbury, New Zealand.

B Department of Zoology, University of Otago, PO Box 56, Dunedin, New Zealand.

C Corresponding author. Email: philip.seddon@stonebow.otago.ac.nz

Wildlife Research 33(3) 193-198 https://doi.org/10.1071/WR05045
Submitted: 9 May 2005  Accepted: 7 April 2006   Published: 31 May 2006

Abstract

There is a need to develop appropriate monitoring methods for cryptic reptile species, such as the endangered New Zealand endemic Otago skink (Oligosoma otagense), that take into account incomplete detectability. A recently developed analytical technique was applied to presence–absence data for Otago skinks to derive robust estimates of both detection probability and site occupancy. The estimated detection probability for Otago skinks was 0.4 (s.e. 0.052), and the estimate of the proportion of the study area occupied by Otago skinks was 0.71 (s.e. 0.11). The data derived from presence–absence surveys in consistently sunny weather, with a standardised scanning and searching technique, provided a good basis for robust estimates of detection probability and of the percentage of area occupied by skinks. This survey technique could be applied to other similarly cryptic reptile species to derive rigorous estimates of site occupancy in order to track changes over time or in response to management interventions. It will be particularly appropriate where precise estimation of absolute abundance is not warranted, or where a simple index of relative abundance may be invalid due to failure of the implicit assumption of constant detectability.


Acknowledgments

We thank the following people for advice and assistance during this study: Darryl MacKenzie, Graeme Loh, Esben Kristensen, and staff of the New Zealand Department of Conservation working at Macraes Flat. Larissa Bailey, Phil Bishop, Henrik Moller, James Reardon and two anonymous referees provided valuable comments on earlier drafts. Karina Holmes kindly provided a map of the study area. This work was supported by a University of Otago Research Grant to PS. CR was partially funded by the New Zealand Department of Conservation Science Advice Fund.


References

Bailey, L. L. , Simmons, T. R. , and Pollock, K. H. (2004). Estimating detection probability parameters for plethodon salamanders using the robust capture–recapture design. Journal of Wildlife Management 68, 1–13.
CrossRef |

Bibby C. J. (1997). Macraes ecological district – survey report for the Protected Natural Areas programme. Department of Conservation, Wellington, New Zealand.

Burnham K. P., and Anderson D. R. (1998). ‘Model Selection and Inference: A Practical Information-Theoretic Approach.’ (Springer-Verlag: New York.)

Burnham, K. P. , and Anderson, D. R. (2001). Kullback–Leibler information as a basis for strong inference in ecological studies. Wildlife Research 28, 111–119.
CrossRef |

Coddington, E. J. , and Cree, A. (1997). Population numbers, response to weather, movements and management of the threatened New Zealand skinks Oligosoma grande and O. otagense in tussock grassland. Pacific Conservation Biology 3, 371–391.


Gu, W. , and Swihart, R. K. (2003). Absent or undetected? Effects of non-detection of species occurrence on wildlife–habitat models. Biological Conservation 116, 195–203.
CrossRef |

Hitchmough R. (2002). New Zealand Threat Classification System lists – 2002. Threatened Species Occasional Publication No. 23. Department of Conservation, Wellington, New Zealand.

Houghton C. (2001). The dispersal and metapopulation dynamics of two skink species, Oligosoma grande and Oligosoma otagense at Macraes Flat, Otago. M.Sc. Thesis, University of Otago, Dunedin, New Zealand.

Kery, M. (2002). Inferring the absence of species – a case study of snakes. Journal of Wildlife Management 66, 330–338.


Lancia R. A., Nichols J. D., and Pollock K. H. (1996). Estimating the number of animals in wildlife populations. In ‘Research and Management Techniques for Wildlife and Habitats’. 5th edn. (Ed. T. A. Bookhaut.) (The Wildlife Society: Bethesda, MD.)

MacKenzie D. I. (2002). Program PRESENCE. Proteus Research and Consulting Ltd. http://www.proteus.co.nz.

MacKenzie, D. I. , and Bailey, L. L. (2004). Assessing the fit of site-occupancy models. Journal of Agricultural Biological & Environmental Statistics 9(3), 300–318.
CrossRef |

MacKenzie, D. I. , and Royle, J. A. (2005). Designing occupancy studies: general advice and allocating survey effort. Journal of Applied Ecology 42, 1105–1114.
CrossRef |

MacKenzie, D. I. , Nichols, J. D. , Lachman, G. B. , Droege, S. , Royle, J. A. , and Langtimm, C. A. (2002). Estimating site occupancy rates when detection probabilities are less than one. Ecology 83, 2248–2255.


MacKenzie, D. I. , Nichols, J. D. , Hines, J. E. , Knutson, M. G. , and Franklin, A. B. (2003). Estimating site occupancy, colonization, and local extinction when a species is detected imperfectly. Ecology 84, 2200–2207.


MacKenzie, D. I. , Nichols, J. D. , Sutton, N. , Kawanishi, K. , and Bailey, L. L. (2005). Improving inferences in population studies of rare species that are detected imperfectly. Ecology 86, 1101–1113.


Marshall L. J. (2001). Home ranges and activity patterns of sympatric grand and Otago skinks. M.Sc. Thesis, University of Otago, Dunedin, New Zealand.

Patterson G. B. (1992). Development of Otago skink and grand skink population census and monitoring techniques. Science and Research Internal Report No. 133. Department of Conservation, Wellington, New Zealand.

Peres-Neto, P. R. , Olden, J. D. , and Jackson, D. A. (2001). Environmentally constrained null models: site suitability as occupancy criterion. Oikos 93, 110–120.
CrossRef |

Royle, J. A. , and Nichols, J. D. (2003). Estimating abundance from repeated presence–absence data or point counts. Ecology 84, 777–790.


Schmidt, B. R. (2003). Count data, detection probabilities, and the demography, dynamics, distribution, and decline of amphibians. Comptes Rendus Biologies 326, S119–S124.Suppl. 1
CrossRef | PubMed |

Silveira, L. , Jacomo, A. T. A. , and Diniz-Filho, J. A. F. (2003). Camera trap, line transect census and track surveys: a comparative evaluation. Biological Conservation 114, 351–355.
CrossRef |

Whitaker A. H. (1996). Impact of agricultural development on grand skink (Oligosoma grande) (Reptilia: Scinicidae) populations at Macraes Flat, Otago, New Zealand. Science for Conservation Report No. 33. Department of Conservation, Wellington, New Zealand.

Whitaker A. H., and Housten D. M. (2002). Grand and Otago skink recovery plan. Draft Threatened Species Recovery Plan. Biodiversity Recovery Unit, Department of Conservation, Wellington, New Zealand.

Whitaker A. H., and Loh G. (1995). Otago skink and grand skink recovery plan (Leiolopisma otagense and L. grande). Threatened Species Recovery Plan No. 14. Threatened Species Unit, Department of Conservation, Wellington, New Zealand.

Williams B. K., Nichols J. D., and Conroy M. J. (2001). ‘Analysis and Management of Animal Populations.’ (Academic Press: San Diego, CA.)



Rent Article (via Deepdyve) Export Citation Cited By (12)