Developing bird friendly transmission power lines in Kenya

Introduction

Kenya Wildlife Sector is guided by the Constitution of Kenya (The Constitution of Kenya, 2010), the Wildlife Conservation and Management Act of 2013 (The Wildlife Conservation and Management Act, 2013) and Vision 2030 (Government of Kenya Vision 2030, 2008) and aims to provide an overarching framework that prioritizes, co-ordinates and inspires participation for the transformation of the wildlife sector in Kenya (Ministry of Tourism and Wildlife (2018). Kenya ranks among the world’s top wildlife destinations with its wildlife being an important economic resource (Ministry of Tourism and Wildlife, 2018). Human activities including habitat fragmentation and degradation, overexploitation, and rapid development have threatened the survival of several species, including raptors through loss of wildlife connectivity areas (Ogada & Keesing, 2010). Among the 1,100 bird species in Kenya, 102, nearly 10%, are raptors which play a crucial role in controlling prey populations, carcass decomposition, disease transmission (Birdlife International, 2022), and maintaining the ecological balance (Donázar et al., 2016).

Overhead power lines pose a significant threat to bird populations worldwide, particularly to endangered species such as raptors that have a high incidence of electrocution (Angelov et al., 2013; Harness et al., 2008; Real et al., 2001). Collisions with electrical wires alone are responsible for the deaths of over one billion birds (Figure 1) annually (Loss et al., 2014). The problem of raptor mortality due to energy infrastructure is pervasive in Africa, with reports of electrocutions in countries such as Kenya, Sudan, and South Africa, where at least 14 diurnal raptor species have been affected (Boshoff et al., 2011; Smallie & Virani, 2010). While larger birds are at greater risk due to their size, smaller birds are also vulnerable to electrocution because transformers contain numerous closely-spaced energized parts (Prinsen et al., 2011). The electricity expansion projects in many African countries e.g. Kenya's “Last Mile Connectivity Project” aimed at providing electricity access to every rural home by 2020 (Kenya Power, 2016), further exacerbates the threat to avian populations.

Figure 1. An electrocuted red tailed hawk (Buteo jamaicensis) observed in the United States of America.

Image by Peter Olsoy.

Licensed under http://creativecommons.org/licenses/by-nc/4.0/.

Power poles and power lines pose a significant threat to birds, with the extent of harm depending on various factors, including the environmental conditions of the site, the morphology and ecology of the bird species, and the technical parameters of the power line construction (Bernardino et al., 2018). The threat is especially pronounced for large birds, such as storks, vultures, herons, and raptors (Barrientos et al., 2012), which frequently migrate long distances and rely on open spaces where energy infrastructure is often developed. As a result, power lines often intersect soaring bird corridors, resulting in significant fatalities. Above-ground power lines pose three major threats to soaring birds: the risk of electrocution, as birds perched on power poles or cables can be electrocuted if they cause short circuits; the risk of collision, as birds may collide with power line cables that are difficult to perceive as obstacles; and the loss of habitat, as power lines may cut through suitable habitats and landscapes for birds, causing avoidance behaviours. To protect bird populations, it is essential to consider these threats when planning and constructing power lines.

Power lines are classified into three categories based on voltage levels, namely high voltage, medium voltage, and low voltage. High voltage or transmission lines (60 kV to 700 kV+) carry electricity at high voltages from power plants to substations (APLIC, 2006). Medium voltage or distribution lines (2.4 kV to 60 kV) deliver low-voltage electricity to individual consumers. Distribution line pylons are typically 8-12 meters high, much smaller than those used on transmission lines. Low voltage lines (120 V to 600 V) are commonly used to connect residential or small commercial customers to utilities. The likelihood of bird collisions with power lines depends on the voltage and construction characteristics of the line (Bevanger, 1994). Birds are more likely to collide with transmission lines carrying a voltage of 110 kV or higher, due to the greater number of conductors, the presence of undetectable earth wires, higher tower heights, and larger distances between towers (Bevanger, 1994; Janss & Ferrer, 1998). Therefore, measures should be taken to reduce the risks of bird collisions, particularly for high-voltage transmission lines.

Policy outcomes and implications

This paragraph describes the methodology used for mapping raptors’ niche distribution and high collision and electrocution risk areas in Kenya. Raptor data was obtained from the Global Biodiversity Information Facility (GBIF, (RRID:SCR_005904)) for the entire Kenya and R software (RRID:SCR_001905) was used to filter and clean the data using the “tidyr” package (Ngila, 2023a). After filtering and cleaning, 11,529 records were used in the modelling. We chose a combination of 19 bioclimatic variables, elevation data from the Shuttle Radar Topographic Mission DEM digital elevation model (SRTM DEM), slope and aspect data calculated from the DEM, and topographic roughness index. We also obtained normalized difference vegetation index (NDVI) data from the National Oceanic Atmospheric Administration (NOAA) website and human influence index (HII) data from Last of the Wild (found here). A variance inflation factor procedure under the “usdm” package in R was used to eliminate variables with a variance inflation factor higher than 10. From an original set of 25 variables, we preserved just the 12 most important factors based on raptors’ ecological needs. The study obtained raptor data from GBIF for the period 2013-2020 (https://doi.org/10.15468/dl.hzyp6v) (Ngila, 2023). Table 1 shows the 12 most important factors that were preserved. To model the distribution of raptors in Kenya, we utilized an ensemble forecasting method from the R package (biomod2 (RRID:SCR_018246)) (Thuiller et al., 2009). This method produces an average of the projections from the ensemble model to obtain the final potential distribution of raptors. The resulting map was binarized into presence-absence values at approximately 1km resolution (Figure 2). To identify areas of high impact of power lines on raptor populations, we obtained power line transmission data from the World Bank and used it to generate collision risk map. The main objective of this policy brief was to propose strategies for bird-friendly transmission power lines in Kenya to mitigate raptor mortality due to collision and electrocution. The results demonstrate significant hotspots of raptor electrocution and collisions in Kenya, particularly in areas where transmission lines overlap with raptor ecological niches (see Figure 3). Furthermore, Table 2 presents the suitable areas for raptor distribution in Kenya, organized by county. The policy brief also highlights the policy gaps in the power transmission infrastructure development Kenya to be addressed in order to achieve bird-friendly transmission power lines.

Figure 2. Binary map of Kenya showing the distribution of raptors in each county - translated into Table 2.

Scales show suitability of raptors with 0 showing absence of raptors and 1 showing presence.

Figure 3. Proposed and current power lines in Kenya passing through suitable niches of raptors.

These transmission lines of >60 kV pose a huge threat to raptors as they are at risk of electrocution and collision.

Kenya had a transmission network of 4766 circuit km at 132 kV and above voltage levels by June 2017, which included 585 km of 400 kV lines, 374.59 km of 220 kV lines, and 839.11 km of 132 kV lines (National Energy Policy, 2018). The Kenya Electricity Transmission Company (KETRACO) is currently constructing 4500 new lines to double the transmission network, introducing high voltage 400kV and 500kV direct current (DC) lines and three major regional interconnectors to Ethiopia, Uganda, and Tanzania. By 2031, it is projected that 16,000 km of transmission lines and associated substations will have been constructed (National Energy Policy, 2018). KETRACO is also planning an additional 4200 km of lines to expand and strengthen the grid. The existing and proposed electric distribution and transmissions in Kenya pass through major suitable raptor habitat in the country (Figure 4). Kenya is a signatory of the Convention of Conservation of migratory species of wild animals, a treaty signed in 1999, to conserve migratory species of birds in migratory routes and preserve habitats commonly used by migratory birds. However, with the proposed electricity transmission network, we see a gap in addressing dangers of electrocution and collision to migratory birds including raptors. The (National Energy Policy, 2018) lacks policy guidelines on bird friendly power lines despite Kenya’s ratification of the convention of conservation of migratory species of wild animals.

Figure 4. A wire marker on a high voltage power line.

These wire markers are very important as they make power lines more visible to raptors and pilots especially near an air-strip.

URL: https://uploadwikimedia.org/wikipedia/commons/2/2c/Wire_marker.jpg.

Licence: Creative Commons CC 1.0 Universal Public Domain Dedication.

Several studies (Alonso et al., 1994; Eccleston & Harness, 2018; Erickson et al., 2005; Janss & Ferrer, 2000; Rioux et al., 2013) have shown that power lines can be particularly dangerous when located along migratory corridors. We therefore suggest the following;

Actionable recommendations

Electricity is a daily necessity though the requisite power lines have a negative impact on the lives of birds. To reduce collisions and electrocution proper measures recommend the following risk reductions:

Despite the limitations mentioned above, the implementations of these recommendations is likely to have several positive impacts on bird populations and the environment. Here are some potential impacts:

Making the skies friendly

There are many types of effective insulation for poles of medium-voltage power lines such as plastic hoods, silicon tubes, long rod insulators, and plastic insulators covering the metal consoles. Some of the top solutions are those which allow the birds to securely perch on poles. For example, line markings to increase the visibility of electric lines has shown to reduce the risk of collisions (Figure 5). A wide range of potential line marking devices has evolved over the years, including spheres, swinging plates, spiral vibration dampers, strips, swan-flight diverters, aerial marker spheres, and tapes. A review of 21 on wire markings shows a reduced bird mortality by 55-94% (Barrientos et al., 2012). Some deterrents, such as rotating mirrors, are aimed at deterring birds from perching nearby, while others such as spikes, act as physical barriers to prevent birds perching close to live cables.

Figure 5. Wire markers near an airstrip on transmission lines.

They are mostly installed near airstrips to make them visible to pilots.

URL: https://upload.wikimedia.org/wikipedia/commons/2/26/Einebenenleitung.jpg.

License: Ikar.us, CC BY 3.0 DE <https://creativecommons.org/licenses/by/3.0/de/deed.en> via Wikimedia Commons.

Discussion

Many elements within a bird's surroundings, such as electric pole type and layout, topography, and habitat, can impact electrocution probability (Lehman et al., 2007). On a large scale, landscape characteristics such as composition of vegetation, the quantity of prey, and the availability of perches can attract raptors or concentrate birds near power lines (Hunting, 2002). At the scale of an individual pole, variables like as geography and relative pole height influence its usefulness as a perch. At the lowest scale (the perch itself), variables such as pole-top layout, clearances between electrical components, physical dimensions of raptors, and raptor behavior all work together to induce electrocutions.

The distribution of raptor habitats in Kenya overlaps with both current and proposed electric infrastructure (Figure 1). Areas with the highest habitat suitability for raptors are primarily located in Narok, Samburu, Laikipia, and Taita-Taveta counties. These areas have a relatively high presence of major national reserves and parks, and conservancies such as Maasai Mara National Reserve, Samburu National Park, Laikipia Conservancy, and Tsavo East and West National Parks. However, the proposed and existing electrical infrastructure extensively overlap with the niche of raptors in these highly suitable areas for raptor species, causing (potential) collisions and electrocutions. Therefore, developing bird-friendly power lines in Kenya can be an effective strategy for reducing the collisions and electrocutions of raptor populations and improving their conservation. Due to interruptions in power supply and maintenance expenses, as well as financial costs and inconveniences to the consumers, bird collisions and electrocutions can also have a negative financial impact on energy firms (Küfeoǧlu & Lehtonen, 2015).

Conclusions

We recommend mapping of important raptor habitats at the electrocution and collision hotspots, retrofitting of dangerous power lines, and engaging with key stakeholders to raise awareness for support of bird-friendly power lines. It is also critical that, following the retrofitting of the power lines, continuous monitoring of the power lines is performed to determine whether the power pole structures used as perches and associated mortalities are correctly identified, and whether the pole modifications prevented or reduced mortalities. Environmental assessments to ensure that new power lines are safe for birds, taking into account the various species in the proximity that could be electrocuted; eagles and vultures have large wingspans, which must be taken into account when specifying spacing distances between phase cables on power lines. Environmental evaluations should also guarantee that the path a power line follows through ecosystems and landscapes is least likely to attract perching birds, e.g. by avoiding, whenever practicably and economically possible wide, flat plains. It is critical that these environmental evaluations have some kind of legal backing to ensure compliance. The successful implementation of these recommendations will require collaboration among various stakeholders, including the government, power companies, conservation organizations, and local communities. By working together, we can create a sustainable energy infrastructure that supports both human development and biodiversity conservation.

In conclusion, this research highlights the critical need for further exploration and development of policies and infrastructure in Kenya to align with the conservation needs of endangered and migratory species. The impact of power line infrastructure on wildlife, particularly raptors and bird species, is a growing concern, and new technologies must be developed to minimize this impact. Additionally, understanding the economic costs and benefits of implementing bird-friendly power line designs and measures is essential to balance them against other societal priorities. Conservation organizations and local communities must be engaged and empowered to participate in efforts to protect raptors and their habitats from the impact of power lines. Finally, power transmission companies need to be incentivized to adopt bird-friendly power line designs and implement measures to reduce the risks of raptor electrocution and collision to ensure a sustainable future for wildlife and their habitats. By conducting further research in these areas, we can develop a more comprehensive understanding of the challenges and opportunities associated with protecting raptors and other wildlife from the impact of power lines and identifying more effective strategies for achieving this goal.