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

Improving the efficiency of wildlife monitoring by estimating detectability: a case study of foxes (Vulpes vulpes) on the Eyre Peninsula, South Australia

S. A. Field A B , A. J. Tyre C , K. H. Thorn D , P. J. O’Connor B E and H. P. Possingham A
+ Author Affiliations
- Author Affiliations

A The Ecology Centre, University of Queensland, St Lucia, Qld 4072, Australia.

B School of Earth and Environmental Sciences, University of Adelaide, Adelaide, SA 5005, Australia.

C School of Natural Resource Sciences, University of Nebraska, Lincoln, NE 68583-0819, USA.

D West Coast Integrated Pest Management Program, PO Box 60, Wudinna, SA 5652, Australia.

E Department of Water, Land and Biodiversity Conservation, GPO Box 2834, Adelaide, SA 5001, Australia.

Wildlife Research 32(3) 253-258 https://doi.org/10.1071/WR05010
Submitted: 21 January 2005  Accepted: 3 May 2005   Published: 22 June 2005

Abstract

Demonstrating the existence of trends in monitoring data is of increasing practical importance to conservation managers wishing to preserve threatened species or reduce the impact of pest species. However, the ability to do so can be compromised if the species in question has low detectability and the true occupancy level or abundance of the species is thus obscured. Zero-inflated models that explicitly model detectability improve the ability to make sound ecological inference in such situations. In this paper we apply an occupancy model including detectability to data from the initial stages of a fox-monitoring program on the Eyre Peninsula, South Australia. We find that detectability is extremely low (<18%) and varies according to season and the presence or absence of roadside vegetation. We show that simple methods of using monitoring data to inform management, such as plotting the raw data or performing logistic regression, fail to accurately diagnose either the status of the fox population or its trajectory over time. We use the results of the detectability model to consider how future monitoring could be redesigned to achieve efficiency gains. A wide range of monitoring programs could benefit from similar analyses, as part of an active adaptive approach to improving monitoring and management.


Acknowledgments

We thank Darryl Mackenzie and an anonymous reviewer for helpful comments on the manuscript, and David Peacock and Kirstin Long for helpful discussions. This work was supported by funding from the Australian Research Council, the West Coast Integrated Pest Management Program and the South Australian Department of Environment and Heritage, in partnership with the Elliston–Le Hunte Animal & Plant Control Board, the Western Animal & Plant Control Board, the Eyre Peninsula Natural Resource Management Group and the Natural Heritage Trust. This paper is a contribution of the University of Nebraska Agricultural Research Division, Lincoln, NE 68583, Journal Series No. 14833.


References

Anderson, D. R. , Burnham, K. P. , and Thompson, W. L. (2000). Null hypothesis testing: problems, prevalence, and an alternative. Journal of Wildlife Management 64, 912–923.


Australian National Audit Office (2001). Performance information for Commonwealth financial assistance under the Natural Heritage Trust. Australian National Audit Office, Canberra.

Australian Natural Resource Management Ministerial Council (2002). National natural resource management monitoring and evaluation framework. http://www.nrm.gov.au/publications/evaluation/index.html [Accessed 6 January 2005.]

Bart, J. , Burnham, K. P. , Dunn, E. H. , Francis, C. M. , and Ralph, C. J. (2004). Goals and strategies for estimating trends in landbird abundance. Journal of Wildlife Management 68, 611–626.


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 |

Burnham K. P., and Anderson D. R. (2002). ‘Model Selection and Multimodel Inference: A Practical Information-theoretic Approach.’ (Springer-Verlag: New York.)

Dixon, P. M. , Olsen, A. R. , and Kahn, B. M. (1998). Measuring trends in ecological resources. Ecological Applications 8, 225–227.


Field S. A., Tyre A., Ball S. J., and Possingham H. P. (2001). Observer error and statistical power: evaluating survey reliability for conservation management. In ‘Modsim 2001: International Congress of Modelling and Simulation’. (Eds F. Ghassemi, P. Whetton, R. Little and M. Littleboy.) pp. 831–836. (MSSANZ: Canberra.)

Field, S. A. , Tyre, A. J. , Rhodes, J. M. , Jonzen, N. , and Possingham, H. P. (2004). Minimizing the cost of environmental management decisions by optimizing statistical thresholds. Ecology Letters 7, 669–675.
CrossRef |

Field, S. A. , Tyre, A. , and Possingham, H. P. (2005). Optimizing allocation of monitoring effort under economic and observational constraints. Journal of Wildlife Management 69, 473–482.


Hall, D. (2000). Zero-inflated Poisson and binomial regression with random effects: a case study. Biometrics 56, 1030–1039.
CrossRef | PubMed |

MacKenzie, D. I. (2005). Was it there? Dealing with imperfect detection for species presence/absence data. Australian and New Zealand Journal of Statistics 47, 65–74.
CrossRef |

MacKenzie, D. I. , and Kendall, W. (2002). How should detection probability be incorporated into estimates of relative abundance? Ecology 83, 2387–2393.


MacKenzie, D. I. , and Royle, J. A. (2005). Designing efficient occupancy studies: general advice and tips on allocation of survey effort. Journal of Applied Ecology 86, 1101–1113.


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 populations studies of rare species that are detected imperfectly. Ecology ,in press


Olson, G. M. , Anthony, R. G. , Forsman, E. D. , Ackers, S. H. , Loschl, P. J. , Reid, J. A. , Dugger, K. M. , Glenn, E. M. , and Ripple, W. J. (2005). Modelling of site occupancy dynamics for northern spotted owls, with emphasis on the effects of barred owls. Journal of Wildlife Management ,in press


Pollock, K. H. , Nichols, J. D. , Simons, T. R. , Farnsworth, G. L. , Bailey, L. L. , and Sauer, J. R. (2002). Large scale wildlife monitoring studies: statistical methods for design and analysis. Environmetrics 13, 105–119.
CrossRef |

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


Saunders G., Coman B., Kinnear J., and Braysher M. (1995). ‘Managing Vertebrate Pests: Foxes.’ (Australian Government Publishing Service: Canberra.)

Shea, K. , Possingham, H. P. , Murdoch, W. W. , and Roush, R. (2002). Active adaptive management in insect pest and weed control: intervention with a plan for learning. Ecological Applications 12, 927–936.


Tyre, A. J. , Tenhumberg, B. , Field, S. A. , Niejalke, D. , Parris, K. , and Possingham, H. P. (2003). Improving precision and reducing bias in biological surveys: estimating false-negative error rates. Ecological Applications 13, 1790–1801.


Venables W. N., Smith D., and The R Development Core Team  (1999–2001). ‘R: A Programming Environment for Data Analysis and Graphics. 1.8.’ http://www.r-project.org

Wintle, B. A. , McCarthy, M. A. , Parris, K. P. , and Burgman, M. A. (2004). Precision and bias of methods for estimating point survey detection probabilities. Ecological Applications 14, 703–712.


Wintle, B. A. , Kavanagh, R. , McCarthy, M. A. , and Burgman, M. A. (2005). Estimating and dealing with detectability in occupancy surveys for forest owls and arboreal marsupials. Journal of Wildlife Management ,in press



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