Impacts of power infrastructure
This project attempts to mitigate the impacts of power generation and transmission infrastructure on birds and other biota. Initial attention was focused on collision impacts associated with powerlines, which mainly affect large, open-country birds such as bustards and cranes that are unable to react rapidly when they encounter aerial obstructions. More recently the project has considered the impacts of renewable energy technologies, including wind and solar power generation.
Wind and solar power generation have much less broad-scale environmental impact than the coal-fired power stations on which South Africa relies for most of its power generation, but both technologies can have significant impacts at a local scale. The aim of this programme is to provide practical solutions to reduce the impacts of renewable energy projects, as well as energy transmission infrastructure, on birds in southern Africa. The programme is run in close collaboration with BirdLife South Africa’s Birds and Renewable Energy programme and the Endangered Wildlife Trust. Modelling the impacts of wind farms on Verreaux’s Eagles Aquila verreauxii is reported separately in the section “Conserving Verreaux’s Eagles”.
Activities in 2019
- Former CB MSc student Christie Craig, now based at the Endangered Wildlife Trust, began work on a project looking at the viability of Blue Cranes Grus paradisea in their core range in the Western Cape and Karoo. She will register for a PhD at the Fitz from Feb 2020. The project has a strong focus on the impact of powerlines on Blue Cranes. In 2019, 150 km of powerline transects were walked in the Swartland and 160 km in the Karoo to quantify avian collisions on powerlines. Preliminary results from the Swartland are similar to surveys done in the Overberg by Jessica Shaw (CB MSc 2008), with four times more mortalities on transmission lines than on distribution lines. Scavenger trials also were conducted, and found little if any loss of carcasses due to scavengers in the Swartland, but more than half of all carcasses in the Karoo disappeared within a few days, suggesting that only a small proportion of powerline casualties will be detected by checking lines every few months. Further trials are planned for 2020.
- Mark Rule from the Bateleurs flew two aerial surveys to count Blue Cranes during the November breeding season, one in the Swartland and one in the Overberg. These flights complemented winter aerial surveys conducted in 2018, and will help to ground-truth estimates of Blue Crane numbers in the Western Cape.
- Christie’s project also focuses on potential socio-economic impacts on Blue Cranes given that the species mainly uses agricultural land in the Western Cape. Interviews were conducted with farmers to gather insights into local agricultural trends, the potential impacts of climate change on land use in the Overberg and Swartland regions, and how these may affect habitat suitability for Blue Cranes. Preliminary observations from the interviews indicate that farmer’s plans to adapt to climate change were mixed and in some cases contradictory. For example, many farmers plan to diversify and focus more on livestock if crop yields decrease, while others plan to move towards a cropping only system, to maximise profits. In 2020, more interviews will be done to help get a clearer sense of what can be expected in this landscape.
- MSc student Robin Colyn continued fieldwork aimed at better understanding the factors determining the distributions of range-restricted larks in the Karoo regions of southern Africa. The Red Lark Certhilauda burra is a species of particular concern, given the large number of wind energy projects planned in the range of this localised, vulnerable species, and the high mortality rate of larks that undertake aerial displays at windfarms. Using a range-finder that also measures the angle of elevation, Robin found that average flight height of displaying males is around 50 m, which definitely places them at risk of collisions (blade heights range from 25-60 m above the ground). Some Red Larks were recorded displaying at more than 150 m above the ground.
- Given the recent expansion of renewable energy development and the associated delineation of development zones (i.e. Renewable Energy Development Zones [REDZ]) throughout the Northern Cape, Robin conducted field studies to identify critical habitat for range-restricted lark species. Using a combination of field data (63 transects and 150 vegetation plots conducted in 2019), remote sensing and predicative modelling, the project aims to delineate core habitats for each species in South Africa: Red Lark, Barlow’s Lark C. barlowi, Sclater’s Lark Spizocorys sclateri and Stark’s Lark S. starki. The first model identified micro-habitats in terms of substratum (calcrete, gravel, sand, rocky outcrop, etc.) and dominant vegetation structure (shrubs, annual forb, grasses, etc.). The next phase of modelling will involve distance sampling to determine lark densities in different habitats, followed by climate change modelling to determine areas of projected stability.
- Robin also completed similar fieldwork and modelling aimed at better understanding the factors determining the distributions of range- restricted larks and pipits in the highland grassland regions of South Africa. The establishment of a REDZ within this region in 2018 could further threaten Yellow-breasted Pipits Hemimacronyx chloris, Rudd’s Larks Heteromirafra ruddi and Botha’s Larks Spizocorys fringillaris. Ecological circuit theory is being used to establish connectivity pathways between identified core habitats and delineate the optimum conservation network for conserving these range-restricted and habitat specialist species.
- Vonica Perold, Peter Ryan and Sam Ralston-Paton (BLSA) reviewed bird mortality monitoring reports at wind energy facilities around South Africa. Although most casualties are raptors and swifts, 130 species of birds have been reported killed at 20 windfarms. Species accumulation models suggest that around 40% of species found in the vicinity of wind farms will be killed at least occasionally. A paper reporting these findings is under review.
- Two papers from Corey Jeal’s CB MSc project on the impacts of a concentrated solar power ‘trough’ facility were published, one recording the relatively minor impacts on birds resulting from this type of facility, and one assessing how macro-invertebrate communities are impacted.
- A paper summarising the efficacy of transmission line marking (using flappers or static flight diverters) to reduce collision mortality in the eastern Nama Karoo, was drafted by Jess Shaw.
Endangered Wildlife Trust-Eskom Strategic Partnership, The Bateleurs, Hans Hoheisen Charitable Trust, Leiden Conservation Fund, Dave Myers.
Prof. Peter Ryan (FIAO, UCT)
A/Prof. Arjun Amar (FIAO, UCT)
Christie Craig (EWT)
Dr Andrew Jenkins (ADU, UCT)
Dr Megan Murgatroyd (FIAO, UCT)
Vonica Perold (FIAO, UCT)
Samantha Ralston-Paton (BLSA)
Dr Tim Reid (ANU, Canberra)
Dr Jess Shaw (Scottish Natural Heritage)
Tanya Smith (EWT)
Student: Robin Colyn (MSc, UCT)