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Planning for Flight Paths: Bird Monitoring at Energy Infrastructure

Planning for Flight Paths: Bird Monitoring at Energy Infrastructure

Focus on Wildlife in Nature

As Africa’ s energy needs increase, and the continent embraces the growth and implementation of green energy, a number of innovative methods have had to be developed to reduce the negative interactions between wildlife and infrastructure.

The Endangered Wildlife Trust’ s Wildlife and Infrastructure (WIN) Unit, has developed numerous innovative methods to reduce these interactions, work to positively influence utilities’ wildlife management policies, and ultimately phase out problematic processes and hardware. Through adaptive management and the development of pioneering and innovative techniques, South Africa is now recognised as a world leader in managing the burden of wildlife damage on electrical infrastructure while addressing the threats to wildlife.

In the final article of the three-part series, the WIN team discusses the monitoring of bird species before and after the construction of energy facilities.

Planning for Flight Paths: Bird Monitoring at Energy Infrastructure

By Hennie de Beer, Tamanna Patel, Matt Pretorius, Oscar Mohale, Kish Chetty

 

Bird monitoring along power lines to reduce collision and electrocution risks in South Africa.

South Africa’ s Wind Energy Facilities (WEF) track bird activities closely, before and after construction. Power lines get no such attention once they run beyond a facility’ s own footprint. This article explains why that gap persists and what it would take to close it.

The line that goes unwatched

Wind energy has benefited from a decade of increasingly refined monitoring protocols. Power lines have not. Guidance does exist, including the World Bank’ s overhead-line survey methods, but it was designed mainly for lines associated with a WEF, not for the thousands of kilometres of transmission and distribution corridors that cross the country independently. For overhead lines outside a WEF, the guidance itself acknowledges that there is no standard method; monitoring is left to case-by-case judgement based on line length, risk and available resources.

Northern Cape wind farms uncovered electrocution risk on their own above-ground collector lines because those lines sat within a monitored WEF footprint. Beyond that footprint, two forms of monitoring exist, but neither systematically catches bird fatalities. Eskom carries out annual/biannual line inspections, carried out by technical staff as part of routine hardware checks, regularly pick up wildlife mortalities, and flag structures that pose a collision or electrocution risk, feeding into the Eskom and Endangered Wildlife Trust Strategic Partnership’ s hotspot identification and structure reconfiguration work.

Certain recent lines have monitoring built into their Environmental Management Programme (EMPr), where the Environmental Impact Assessment (EIA) process identified them as crossing sensitive areas under the National Screening Tool and DFFE Powerlines Strategic Environmental Assessments (SEAs). The opportunity is to build on that foundation, not to start from nothing. Folding a short wildlife checklist into the hardware inspections technical staff already carry out, rather than treating bird monitoring as a separate exercise, could extend coverage across the network at a fraction of the cost of a standalone programme. The same logic applies to lines built before the National Screening Tool existed: routine inspections could flag them for a one-off risk review rather than requiring a wholesale audit of the older network.

Species we still do not understand well enough

Some species remain difficult to protect because the available data is still limited. The Black Harrier (Circus maurus) is an exception. Near-endemic to southern Africa and listed as Endangered, it is one of the better-studied cases: its regional population is estimated at only 733 to 938 mature individuals and is declining by about 2.3% each year. Population viability modelling suggests that the species has a greater than 50% chance of extinction within 75 to 100 years if fatalities increase by only three to five adult birds per year above baseline mortality.

BirdLife South Africa’ s 2025 Red Data Book assessment records at least 13 confirmed adult Black Harrier fatalities across South Africa’ s 33 operational WEFs since 2014. Once under-detection is considered, the true number could be closer to double, leaving little margin before the population reaches the fatality threshold identified by modelling.

Bustards present a different kind of knowledge gap. Ludwig’ s Bustard (Neotis ludwigii), which is Endangered and nomadic, and Denham’ s Bustard (Neotis denhami), listed as Vulnerable, appear in national fatality records at turbines and along power lines. At turbines, Ludwig’ s Bustard and Denham’ s Bustard, the recorded numbers are still single digits, too few to reveal which routes, seasons or conditions carry the highest risk. The picture for power line fatalities is less settled: current published data understates the true toll, with more recent findings not yet in print suggesting the numbers are higher.

Verreaux’ s Eagle (Aquila verreauxii) and Martial Eagle (Polemaetus bellicosus) face a related problem at a larger scale. Both are killed by turbine collision and by electrocution on power lines, but no single dataset currently combines turbine and power-line records to show the total pressure on either population.

Where the turbine solution runs out

Bird Flight Diverter (BFD) design must match a species’ activity pattern, and proving that a diverter works requires a genuine Before-After-Control-Impact (BACI) study, rather than simply observing a decline in fatalities. For turbines, the practical approach is deliberate zoning: selecting turbines with comparable pre-treatment collision rates, then leaving some unmarked controls while fitting the rest with diverters. Zoning by risk level and treating only the high-risk turbines would bias the comparison from the outset, since the control and treatment groups need equivalent baseline exposure for the before-after comparison to hold.

It is tempting to assume that the same model can be carried over to power lines. It cannot, at least not cleanly. BACI’ s statistical strength depends on collision rates being comparable between control and treatment groups before mitigation begins. At a single WEF, turbines usually share broadly similar terrain, spacing and species exposure, making it relatively straightforward to identify suitable controls.

Power lines are different. A line can change character within only a few kilometres as span height, surrounding habitat and bird movement patterns shift from one section to the next. Treating an unmarked span as a control without first confirming that its pre-mitigation collision rate resembles that of the marked span is not a genuine comparison. A BACI study based on that assumption may look rigorous while producing unreliable conclusions.

The answer is not to delay mitigation until a perfect study becomes possible. Developers often have to prioritise immediate risk reduction over years of pre-marking baseline data collection because installation costs and project timelines do not disappear. The more practical solution is to design comparability into BFD rollouts from the outset, so that marking a line and evaluating whether the marking works are not treated as competing objectives.

Turning gaps into a plan

None of this erases what the first two articles in this series documented: pre-construction surveys can shape turbine layouts, post-construction monitoring can identify what those surveys missed, and adaptive management can measurably reduce fatalities. It does mean that the next phase of work has a clear focus:

  • Develop standardised guidelines for power-line monitoring, built for linear corridors rather than adapted point-based turbine protocols.
  • Extend post-construction monitoring requirements further along transmission and distribution networks, instead of stopping at WEF boundaries.
  • Build secondary ecological effects, such as those exposed in the Northern Cape case, into monitoring protocols from the start.
  • Use GPS tracking studies and updated distribution mapping to close data gaps for bustards, eagles and the Black Harrier.
  • Feed post-construction fatality data back into pre-construction collision-risk models, for both WEF and power lines, so each new and existing project improves on the predictions of earlier ones.
  • Use automated detection systems, including cameras and radar, to complement Shutdown on Demand where fast response is needed.
  • Create a shared industry database of collision and electrocution records so new projects can learn from the full evidence base, not only from site-specific reports.
  • Design BACI studies for power lines only where comparability between control and treatment spans is established before marking begins.

South Africa’ s wind sector has spent a decade building the monitoring culture described in this series. Applying the same investment to power lines is within reach. It begins by treating these gaps not as a verdict on work already done, but as the next items on a practical working list.

Further reading

  • BirdLife South Africa. 2025. Summary Bird Monitoring Reports from Operational Wind Energy Facilities in South Africa. BirdLife South Africa Occasional Report Series No. 3. BirdLife South Africa, Johannesburg, South Africa.
  • https://www.birdlife.org.za/wp-content/uploads/2025/02/Summary-of-Bird-Monitoring-Reports-Final-Version.pdf
  • Cervantes, F., Martins, M., and Simmons, R.E. 2022. Population viability assessment of an endangered raptor using detection/non-detection data reveals susceptibility to anthropogenic impacts. Royal Society Open Science 9: 220043.
  • International Finance Corporation, European Bank for Reconstruction and Development, and Kreditanstalt für Wiederaufbau. 2023. Post-Construction Bird and Bat Fatality Monitoring for Onshore Wind Energy Facilities in Emerging Market Countries: Good Practice Handbook and Decision Support Tool. Washington, DC: International Finance Corporation.
  • Lee, A.T.K., Rose, S., Banda, S., Bezeng, S.B., Maphalala, M.I., Maphisa, D.H., and Smit-Robinson, H.A. (eds). 2025. The 2025 Red Data Book of Birds of South Africa, Lesotho and Eswatini. Johannesburg, South Africa: BirdLife South Africa.
  • Smallie, J., Froneman, A., Smith, D.L., and Mulvaney, J.M. 2024. Shutdown on Demand for the mitigation of bird collision risk at onshore wind farms in South Africa. BirdLife South Africa, Johannesburg, South Africa.
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Camera Traps Monitor Bird Activity on Power lines

Camera Traps Monitor Bird Activity on Power lines

In the Field

Camera Traps Monitor Bird Activity on Power lines

By Amos Letsoalo, Wildlife and Nature Unit senior field officer

 

Wildlife monitoring camera installed on power infrastructure in the Northern Cape

The EWT’ s Wildlife and Infrastructure Unit (WIN), in collaboration with National Transmission Company of SA (NTCSA), has installed camera traps on a power line within a nature reserve In the Northern Cape to understand incidents involving birds along this section of line.

The use of camera trap technology will help us to monitor bird interactions with power infrastructure on a Boundary Olien 1 power line within the Dronfield Nature Reserve outside Kimberley.  This is because the power line has had several wildlife and electrical infrastructure incidents in the recent past, including vulture collisions.

Following the installation of three camera traps a few months ago, a fourth one was added to the line, to increase monitoring of the area. 

With these four technological eyes now monitoring the power lines, we hope to gather more data on how birds interact with the power lines. This   will not only help us better understand these interactions, but also assist us in applying relevant mitigation measures to minimise negative impacts on both wildlife and power lines and other electrical infrastructure.

Without this intervention the impact on vulture populations in the area will continue. The Wildlife in Nature Unit is appealing to the public to report any incidents involving power lines and electrical infrastructure to amosl@ewt.org so we can take the steps needed to protect the wildlife and power lines.

 

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Planning for Flight Paths: Bird Monitoring at Energy Infrastructure

Planning for Flight Paths: Bird Monitoring at Energy Infrastructure

Focus on Wildlife in Nature

As Africa’ s energy needs increase, and the continent embraces the growth and implementation of green energy, a number of innovative methods have had to be developed to reduce the negative interactions between wildlife and infrastructure.

The Endangered Wildlife Trust’ s Wildlife and Infrastructure  Unit, has developed numerous innovative methods to reduce these interactions, work to positively influence utilities’ wildlife management policies, and ultimately phase out problematic processes and hardware. Through adaptive management and the development of pioneering and innovative techniques, South Africa is now recognised as a world leader in managing the burden of wildlife damage on electrical infrastructure while addressing the threats to wildlife.

This article is the first in a series of three about the work being done by the EWT to mitigate the effect of power lines on wildlife, particular birds.

 

Planning for Flight Paths: Bird Monitoring at Energy Infrastructure

By the Wildlife and Infrastructure team

 

Raptors interacting with electrical infrastructure in open landscapes

Before a single wind turbine or power line is built in South Africa, there is a crucial window in the pre-construction process to prevent bird mortalities.  This ranges from infrastructure design to mitigation measures, such as the installation of devices on power lines to reduce bird collisions. 

Among the measures incorporated in South Africa’s renewable energy expansion us ensuring that infrastructure is designed with biodiversity in mind. At the heart of this approach is pre-construction monitoring, which informs infrastructure design based on how birds use the landscape, rather than treating it as a simple regulatory requirement.

This article explains the pre-construction process, the relevant regulatory framework, and the field surveys used to map bird activity. It also explores how these insights are translated into practical design changes that minimise collision risks and protect vulnerable species.

BirdLife South Africa states in its 2025 review that of the 2,444 unique bird fatality incidents recorded at 33 Wind Energy Facilities, losses were attributed turbine collisions, power lines and other impacts. These incidents involved 202 species, of which 198 were recorded as turbine collisions.

Understanding how pre-construction monitoring and regulatory pathways shape infrastructure design is critical to preventing these losses. Notable Species of Conservation Concern include the Cape Vulture, White-backed Vulture, Verreaux’s Eagle, Martial Eagle, Black Harrier, Secretary Bird, Blue Crane, Greater Flamingo, Lesser Flamingo, Denham’ s Bustard and Ludwig Bustard.

Understanding the Environmental Impact Assessment process

Wind Energy Facilities (WEF) and overhead power lines (both transmission and distribution voltage) pose collision and electrocution risks to birds.  All follow different regulatory pathways depending on project scale and environmental sensitivity.

Energy projects may require an Environmental Impact Assessment (EIA) before construction is authorised. This depends on the threshold triggered. An EIA evaluates environmental, social and economic effects through screening, scoping, baseline studies and impact assessments, using surveys and models. The findings are compiled in a report, reviewed by the public, specialists and regulators, and may be approved with conditions or declined.

Approved projects then follow an Environmental Management Programme (EMPr), a legally-binding process that dictates how a project is managed. For wind energy facilities, operational avifaunal monitoring is a standard condition of an Environmental Authorisation (EA), ensuring bird collision risks are tracked and mitigated adaptively. For transmission power lines, monitoring requirements vary based on route sensitivity and specialist recommendations, though incident reporting is typically required. Distribution lines approved through registration for exclusion, however, face no such operational oversight — a regulatory gap explored later in this article.

Desktop screening

Desktop screening begins with the Department of Forestry, Fisheries and the Environment’ s Environmental Screening Tool (https://screening.environment.gov.za/screeningtool/#/pages/welcome), which assesses avifaunal sensitivity and determines whether projects require a full EIA. Distribution lines in low- to medium-sensitivity areas can proceed through registration for exclusion. Avifaunal specialists then review spatial data on raptor nests, vulture colonies, Important Bird Biodiversity Areas, collision hotspots and migration routes. This identifies where development may harm key species. For wind farms, this flags priority species and thermal lift zones. For power lines, it maps wetland crossings, bustard corridors and raptor breeding areas.

Pre-construction surveys

For wind energy facilities, once risks have been identified to avifauna during the screening process, 12-month pre-construction surveys are legally required as a standard EA condition. This extended monitoring ensures breeding seasons, migration pulses and seasonal weather patterns are captured, requiring observation across all four seasons. Surveys record species presence, migration and breeding, noting flight heights and behaviours, such as whether vultures soar at turbine-elevated heights or eagles hunt near the ground. This data informs collision-risk models that predict turbine threats.

Power line pre-construction surveys follow a different approach. Rather than continuous monthly monitoring, specialists conduct seasonal site visits (typically 2 – 4 surveys across seasons) focused on documenting raptor nests, identifying perching structures, mapping bustard and flamingo flight corridors, and assessing electrocution and collision risks at specific high-risk spans. Distribution lines approved through registration for exclusion require only desktop assessment and site verification, with no extended seasonal monitoring. This is a regulatory gap that means seasonal flight patterns may go undetected until mortalities occur.

Design changes that work

Turbine layouts are redrawn based on survey results. Verreaux’s Eagle nests earn buffer zones of at least 3.7 kilometres, the minimum distance recommended in BirdLife South Africa’s guidelines, though actual fatalities have occurred up to 7.5 kilometres from known nests. Areas where Cape Vultures soar become no-go zones, regardless of wind resource. Collision risk modelling identifies high-risk positions, which are relocated or removed. Turbines are micro-sited to avoid hotspots such as ridge edges or thermal lift zones. Environmental Authorisation conditions require these changes before construction, making bird protection legally binding.

Power line routes avoid bustard and flamingo corridors, wetlands and raptor breeding areas. Engineers specify raptor-safe poles/tower designs, with adequate separation between energised and grounded components to prevent electrocution.  Poles in raptor perching areas are insulated, and bird flight diverters mark high-risk are used where routing cannot eliminate collisions. Within wind farms, underground medium-voltage collector lines are increasingly standard practice, avoiding the electrocution trap of overhead networks. In the Northern Cape, two wind farms were installed with over-head collector lines. Over five years, these lines killed 12 Verreaux’s Eagles and three Martial Eagles through electrocution, a design flaw newer projects have corrected. For high-voltage transmission lines, however, underground cabling remains expensive, leaving mitigation reliant on routing, insulation and diverters rather than burial. These design changes prevent mortalities we will never see, the birds that would have died, but were not counted. When routes avoid wetlands, cranes and flamingos will not collide with wires. When poles are designed correctly and/or insulated, raptors will not be electrocuted.

The distribution line blind spot

“Registration for exclusion” is a streamlined National Environmental Management Act (NEMA) pathway that allows certain listed activities in low- to medium-sensitivity areas to proceed without full Competent Authority review. For distribution power lines (typically below 132kV, including municipal and Eskom Distribution infrastructure), this means projects can self-certify compliance rather than having to obtain an EA with enforceable conditions. Transmission lines (132kV and above) are excluded from this pathway and must follow full EA processes regardless of sensitivity.

While the exclusion route requires upfront specialist assessment, site verification and public participation, no operational monitoring is mandated. Distribution lines need not report bird collisions, audit mitigation effectiveness, or adapt when initial predictions prove inadequate. Critically, collector lines within wind farms undergo full EIA scrutiny of pole design, insulation and routing, while Eskom and municipal distribution lines below 132 kV bypass this oversight entirely through exclusion. Mitigation measures are not enforceable, leaving implementation to the utility’s discretion. The critical gap is that infrastructure can create risks that desktop assessments never anticipated. Poles provide perching opportunities in open landscapes, attracting raptors and corvids to areas previously flagged as low risk. Without operational monitoring, these emergent threats go undetected until mortalities accumulate.

Bird mortalities continue to occur on distribution lines below 132kV, with raptors electrocuted on poles and bustards and flamingos colliding with unmarked spans. Without operational monitoring requirements, these impacts go undocumented and unaddressed. The ongoing oversight that characterises full EAs disappears once construction begins, leaving responsibility with utilities, but no legal obligations to mitigate. This is particularly problematic for lines crossing seasonal flight paths, where post-construction bird use may differ dramatically from desktop predictions.

The Prevention Principle

The best collision is the one that never happens. Pre-construction monitoring embodies this prevention principle—design infrastructure that coexists with birds instead of threatening their survival. Yet when infrastructure proceeds through registration for exclusion, we gamble with species that cannot afford losses: Cape Vultures whose populations are declining, Verreaux’s Eagles rearing chicks near future collision zones and bustards crossing landscapes where unmarked wires cause mortalities. Smart planning is not red tape; it’s the difference between infrastructure designed around birds and infrastructure built blind to consequences.

Where full Environmental Authorisations require operational monitoring, systematic tracking reveals whether predictions prove accurate and mitigation works as intended. Sometimes monitoring uncovers surprises – species more vulnerable than anticipated or seasonal patterns missed in desktop assessments.

Article 2 explores how this adaptive management deploys targeted interventions that prevent mortalities. These safeguards apply where full EA processes are in place. For excluded infrastructure, birds pay the price of our regulatory blind spot.

 

Further reading

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