Ecological Uses of Vertebrate Indicator Species: A Critique

Abstract

Plant and animal species have been used for decades as indicators of air and water quality and agricultural and range conditions. Increasingly, vertebrates are used to assess population trends and habitat quality for other species. In this paper we review the conceptual bases, assumptions, and published guidelines for selection and use of vertebrates as ecological indicators. We conclude that an absence of precise definitions and procedures, confounded criteria used to select species, and discordance with ecological literature severely weaken the effectiveness and credibility of using vertebrates as ecological indicators. In many cases the use of ecological indicator species is inappropriate, but when necessary, the following recommendations will make their use more rigorous: (1) clearly state assessment goals, (2) use indicators only when other assessment options are unavailable, (3) choose indicator species by explicitly defined criteria that are in accord with assessment goals, (4) include all species that fulfill stated selection criteria (5) know the biology of the indicator in detail, and treat the indicator as a formal estimator in conceptual and statistical models, (6) identify and define sources of subjectivity when selecting monitoring and intetpreting indicator species, (7) submit assessment design, methods of data collection and statistical analysis, interpretations, and recommendations to peer review and (8) direct research at developing an overall strategy for monitoring wildlife that accounts for natural variability in population attributes and incorporates concepts from landscape ecology.

Ground-dwelling reptile assemblages in selectively harvested dry sclerophyll forest in south-east Queensland

“…The use of indicator species as surrogates for other aspects of biodiversity or as surrogates for demonstrating changes in ecological processes or ecosystem patterns has come under much scrutiny and, as a management tool, should be treated with some care (Landres et al 1988;Spellerberg 1994;Burgman and Lindenmayer 1998).…”

“…This has given rise to the idea of management "indicator" species (Thomas 1972;Landres et al 1988), recently reviewed by Lindenmayer et al (2000) in an Australian context. The concept is based on a number of precepts that include: species associations exist within nature and therefore some species might act as surrogates for the presence or absence of other species; species are sensitive to environmental change or changes to cyclical patterns outside the norm and; species are sensitive to the effects of a disturbance regime or management designed to mitigate the impacts of disturbance.…”

Stock Complexes for Fisheries Management in the Gulf of Mexico

“…These biases might generate spurious correlations that would be difficult to separate from actual population trends (May and MacArthur 1972;Landres et al 1988;Leibold 1995;Niemi et al 1997;Shaul et al 2007;Shertzer and Williams 2008). In the absence of a fully resolved analysis of indices of abundance that adequately controls for the confounding variability introduced by environmental forcing, fishing pressure, and fisheries management regulations, a comprehensive understanding of co-occurrence in the catch across sectors is critical to simplifying ACL/AM management.…”

Suitability of Butterflies as Indicators of Ecosystem Condition: A Comparison of Butterfly Diversity across four habitats in Gir Wildlife Sanctuary

“…They are considered to be one of the several insects that are a potential ecological indicator of forest condition. Indicator species are thought to either signal the presence /abundance of other species, or to signal chemical/physical changes in the environment through changes in their own presence or abundance (Landres et al,1988;Simberloff,1998). The second of these types of indicators is referred to as an ecological indicator (McGeoch 1998 Landres et al,1988;Rodriguez et al,1998 andFerris andHumphrey,1999 have proposed criteria for selecting indicator species.…”