Are ‘Ecological-Disturbance Indicator Species’ Effective?

One of the biggest challenges in conservation projects – whether it is traditional conservation, habitat restoration, “Reduced Emissions from Deforestation and Degradation (REDD+) projects,” or other types of land-management – is understanding and being able to monitor how flora and fauna are responding to changes. This is particularly difficult in tropical forests, where multi-species field studies are not only difficult and complicated, but costly as well. One solution is to use “ecological-disturbance indicator species (EDIS)” to act as a type of bellwether. The idea is that these EDIS’ are sensitive to, and demonstrate the effects of, environmental change and can give conservationists a sense of how other species might or might not be coping as well. Still, even with the potential of using EDIS’ to make conservation projects more efficient, there is a desire to understand what EDIS’ are the best candidates, who may show “high performance” and “cost effectiveness” in their task, as it were.

The purpose of this study was to “identify high performance EDIS for small vertebrates in tropical Andean forests exhibiting differential anthropogenic disturbance.” Using a variety of “standard field techniques,” the researchers set out to compare the cost-effectiveness of EDIS for birds, bats, small mammals, and leaf-litter lizards. They conducted this research in two different tropical Andean montane reserves, surveying species over the course of several expeditions. All in all, they recorded 172 small vertebrate species, 7 species of leaf-litter lizards, 9 species of small mammals, 11 species of bats, and 145 species of birds. Based on their calculations, they found that the “total costs of surveys varied among taxa (range from 1490€ for bats to 6230€ for leaf-litter lizards)” while the proportion of salary costs were 59% for bats, 97% for birds, 74% for small mammals, and 92% for leaf-litter lizards. Though all the surveys captured a good portion of estimated species richness, birds generated the “cheapest single EDIS”; the Andean Solitare bird “was a detector species of primary forest at a survey cost of 204€”

Though the study here was quite specific in its location and objectives, the researchers note that selecting the most cost-effective EDIS is “highly dependent on conservation objectives,” and likely the location as well. For conservationists and wildlife advocates, the study represents a specific way of evaluating the costs of monitoring.