This methodology is split into two sections: first, selecting the indicator species, and second, monitoring them.

Selecting indicator species

Careful selection of indicator species to monitor is crucial to the success and accuracy of this indicator. Here we follow the guidance laid out in the Biodiversity Indicators for Site-based Impacts methodology (UNEP-WCMC, 2020), and have adapted it for use in tracking positive impacts at a project level.

A set of six criteria have been defined to screen potential indicator species, covering the vulnerability of the species to project-induced pressures, the suitability of the species to provide indicators, and the significance of the species. They are:

Present at site. An initial list of species likely to be present can be drawn from IBAT (taken from The IUCN Red List of Threatened Species information and average species ranges). Species that do not appear within the IBAT list but are known from site-level documentation can then be added to the list.
Impacted by project-induced pressures, or reduction in pressures. Consider the target of the project intervention, and identify which pressures the investment or project aims to alleviate (for example, land use change, or water abstraction), and which may remain. Work with local experts to consider which of the species present will be affected by these pressures.
Feasibly monitored. A key aspect of an indicator species is that it is possible to monitor regularly. For example, if a population is very small and/or not often encountered, or very transient, then changes in population size would be hard to detect.
Responsive to change. Consideration should be given to how a species is likely to respond to changes related to project activities. For example, species with long lifecycles may not be suitable as there may be a significant time lag between the change in pressure and a noticeable change in the population of the species. Similarly, species with large population fluctuations may not be suitable as the fluctuation may mask long-term trends.
Representative of the effect on wider biodiversity. Indicator species should provide a representation of the effect of a pressure on biodiversity more widely. For example, a forest-dependent species could be a good indicator species in a project aiming to reduce logging pressures on a forest, as an increase in its population is likely to mirror the trend in other forest-dependent species that are affected by the pressure.
Threatened or important. The most significant consequences of a project’s potential impact at a site are likely to be associated with threatened or important species. Species which are Critically Endangered, Endangered or Vulnerable either globally or nationally (identified via the IUCN Red List), or endemic or culturally important (identified via local experts and stakeholders, including local communities) should therefore be prioritized.

Further information on the above can be found in the Biodiversity Indicators for Site-Based Impacts guidance, pages 27-31. We would recommend consulting with local ecologists to ensure the indicator species selected is representative.

Monitoring population over time

Once the indicator species (or group of species) is selected, a baseline should be collected ahead of the project intervention starting. Then the change in population should be monitored over the course of the project, ideally on a yearly basis. Percentage change in the population, compared to the baseline, can then be calculated.

The method for species monitoring is up to the user, but should be consistent throughout the project lifecycle. This could take the form of surveys run by local ecologists, or approaches such as eDNA or bioacoustics, where those techniques are considered adequate for estimating abundance. Whichever method is chosen, it should be suited to the species selected – bioacoustics, for example, will not be able to monitor population changes in a silent snake species.

Investor Guide to Environmental and Social Opportunities and Risks: Indonesia