The power of expert opinion in ecological models using Bayesian methods: impact of grazing on birds

Martin, Tara G., Kuhnert, Petra M., Mengersen, Kerrie L., & Possingham, Hugh P. (2005) The power of expert opinion in ecological models using Bayesian methods: impact of grazing on birds. Ecological Applications, 15(1), pp. 266-280.


One of our greatest challenges as researchers is predicting the impact of land use on biota, and predicting the impact of livestock grazing on birds is no exception. Insufficient data and poor survey design often yield results that are not statistically significant or difficult to interpret because researchers cannot disentangle the effects of grazing from other disturbances. This has resulted in few publications on the impact of grazing on birds alone. Ecologists with extensive experience in bird ecology in grazed landscapes could inform an analysis when time and money constraints limit the amount of data that can be collected. Using responses from 20 well-recognised ecologists throughout Australia, we captured this expert knowledge and incorporated it into a statistical model using Bayesian methods. Although relatively new to ecology, Bayesian methods allow straightforward probability statements to be made about specific models or scenarios and the integration of different types of information, including scientific judgement, while formally accommodating and incorporating the uncertainty in the information provided. Data on bird density was collected across three levels of grazing (no/low, moderate, and high) typical of sub-tropical Australia. This field data was used in conjunction with expert data to produce estimates of species persistence under grazing. The addition of expert data through priors in our model strengthened results under at least one grazing model for all but one bird species examined. When experts were in agreement, credible intervals were tightened substantially, whereas, when experts were in disagreement, results were similar to those obtained in the absence of expert information. In fields where there is extensive expert knowledge, yet little published data, the use of expert opinion is a cost-effective way of making more confident predictions about the effect of management on biodiversity.

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137 citations in Scopus
127 citations in Web of Science®
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ID Code: 900
Item Type: Journal Article
Refereed: Yes
Additional URLs:
Keywords: elicitation, livestock grazing, Markov chain Monte Carlo, mixture model, multiple experts, two, component model, WinBUGS, woodland bird conservation, zero inflation
ISSN: 1051-0761
Subjects: Australian and New Zealand Standard Research Classification > MATHEMATICAL SCIENCES (010000) > STATISTICS (010400) > Applied Statistics (010401)
Divisions: Past > QUT Faculties & Divisions > Faculty of Science and Technology
Copyright Owner: Copyright 2005 Ecological Society of America
Copyright Statement: Copyright by the Ecological Society of America: Martin, Tara G., Kuhnert, Petra M., Mengersen, Kerrie, Possingham, Hugh P. 2005: THE POWER OF EXPERT OPINION IN ECOLOGICAL MODELS USING BAYESIAN METHODS: IMPACT OF GRAZING ON BIRDS. Ecological Applications: Vol. 15, No. 1, pp. 266–280. This journal is available online.
Deposited On: 21 Mar 2005 00:00
Last Modified: 29 Feb 2012 13:17

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