Abstract
The wind‐energy industry is expanding rapidly in southern Africa. While experiences in other parts of the world suggest that this industry may be detrimental to birds (through the destruction of habitat, the displacement of populations from preferred habitat, and collision mortality with wind turbines, guyed masts and associated power lines), these effects are highly site- and taxon-specific. Raptors, large terrestrial species and wetland birds are likely to be most vulnerable, and areas of higher topographic relief are often implicated in negative impact scenarios.
In order to fully understand and successfully mitigate the possible impacts of wind energy on the region’s birds (and to bring the local situation into line with international best practice in this field), it is essential that objective, structured and scientific monitoring of both resident and migrating birds be initiated at all proposed wind‐energy development sites.
The Birds and Renewable Energy Specialist Group (BARESG), convened by the Wildlife and Energy Programme of the Endangered Wildlife Trust, and BirdLife South Africa, proposes the following guidelines and monitoring protocols for evaluating wind energy development proposals, including a tiered assessment process as listed below.
- Scoping – a brief site visit informs a desk-top assessment of likely avifauna present, possible impacts, and the design of a site-specific survey and monitoring protocols.
- Pre-construction monitoring and impact assessment – a full assessment of the significance of likely impacts and available mitigation options, based on the results of systematic and quantified monitoring.
- Construction‐phase monitoring – not always necessary, but can help determine if proposed mitigation measures are implemented and are effective, and identify triggers of any observed changes.
- Post-construction monitoring – repetition of the pre-construction monitoring, plus the collection of mortality data, to develop a complete before and after picture of impacts, and refine mitigation measures.
- If warranted, more detailed and intensive research on affected threatened or potentially threatened species.
To streamline this approach, a shortlist of priority species should be drawn up at the scoping stage. Priority species should include threatened or rare birds, in particular those unique to the region, and especially those that may be susceptible to wind-‐energy impacts. These species should be the primary (but not the sole) focus of subsequent monitoring and assessment.
Similarly, the amount of monitoring effort required at each site should be set in terms of the anticipated sensitivity of the local avifauna and the prevalence of contributing environmental conditions (for example, the diversity and relative abundance of priority species present, proximity to important flyways, wetlands or other focal sites, and topographic complexity).
On-site work should be coupled with the collection of directly comparable data at a nearby, closely-matched reference (control) site where possible. This will provide much-needed context for the analysis of pre- vs. post-construction monitoring data.
In some situations, where proposed wind-energy developments are likely to impinge on flyways used by relatively large numbers of threatened and impact‐sensitive birds, and particularly where these movements are likely to take place at night or in conditions of poor visibility (e.g. the Cape Columbine Peninsula), it may be necessary to use radar to gather sufficient information on flight paths to fully evaluate the development proposal and inform mitigation requirements.
Pre-construction monitoring will require periodic surveys of both the development and reference sites. These surveys should be sufficiently frequent to adequately sample all major variations in environmental conditions, with no fewer than four surveys spanning the annual cycle. Variables measured/mapped on each survey should include (i) density estimates for small terrestrial birds (in most cases not priority species, but potentially affected on a landscape scale by multiple developments in one area), (ii) census counts, density estimates or abundance indices for large terrestrial birds and raptors, (iii) passage rates of birds flying through the proposed development area (including nocturnal movements, where appropriate), (iv) evidence of breeding at any focal species sites, (v) bird numbers at any focal wetlands, and (vi) full details of any incidental sightings of priority species.
Post‐construction monitoring should effectively duplicate the pre‐construction monitoring work, with the addition of surveys for avian collision victims under the turbines, and collision and electrocution victims under the ancillary power infrastructure. Estimates of fatality rates should take into account scavenger removal and searcher efficiency.
While analysis and reporting on an individual development basis will be the responsibility of the relevant avifaunal specialist, all data emanating from the above process should also be housed centrally by BARESG and/or the South African National Biodiversity Institute (SANBI) to facilitate the assessment of results on a multi-project, landscape and national scale.
These guidelines will be revised periodically as required, based on experience gained in implementing them, and on‐going input from various sectors. This is the third edition.
A list of qualified avian specialists who have agreed to adhere to these guidelines is available at www.birdlife.org.za and www.ewt.org.za.