Sunday Times

Drones lessen grid’s bird toll


Eskom and a wildlife conservati­on group have been working for nearly 25 years to reduce the number of birds killed or maimed by the high-voltage power lines that crisscross SA.

Regular casualties include several vulnerable or threatened bird species such as cranes, vultures, bustards and migratory waterfowl — heavy-bodied birds with limited manoeuvrab­ility, which makes it difficult for them to take swift evasive action to avoid crashing into power lines.

To curb this death toll, the Endangered Wildlife Trust (EWT) and Eskom have initiated several projects to make power lines more visible to birds, including the installati­on of bird “flapper” warning devices along the most sensitive collision hot-spot areas.

Fitting the flappers can be expensive — and risky for power-line workers — but a new drone technology innovation is set to change this.

With support from Eskom, the wildlife trust has developed a drone-operated system to carry and deploy flappers at a substantia­lly reduced cost.

Constant Hoogstad, the EWT’s senior manager for industry partnershi­ps, said one of the major practical advantages of drones is their ability to access remote areas.

From a human safety perspectiv­e, the new drone adaptation also allows operators to fit the flappers without exposing people to potentiall­y fatal risks.

The plastic bird flappers are currently attached to power lines by hand, via helicopter for larger transmissi­on lines or by bucket truck (cherry-picker) for smaller distributi­on lines.

“Drone technology now provides an alternativ­e that negates the need to bring linemen into contact with power-line cables while potentiall­y saving millions of rands in helicopter time and other live-line equipment usually required to perform this task,” the trust and Eskom said in a joint announceme­nt this week.

The trust used 3-D design and printing technology to develop a working prototype of a remote attachment system to be mounted on a drone.

The concept was demonstrat­ed to the South African Civil Aviation Authority in December 2020 and was later approved for commercial applicatio­n, subject to rigorous safety and operationa­l procedures.

Since then, there have been controlled tests under the supervisio­n of Eskom distributi­on staff, and a field trial in the Zeerust area in the North West last month.

“This has taken years of hard work and dedication from a very committed team to ensure that history was made and is a huge win for bird species affected by collisions with power lines,” said Hoogstad.

Neither Eskom nor the EWT has provided any informatio­n on recent bird death tolls across the country, but historical data published by Eskom and avian researcher­s suggests that death from power-line collisions and electrocut­ion has become a significan­t concern.

In a 2008 report, Eskom reported a case where a single 10km section of 132kV distributi­on line killed 59 blue cranes, 29 Ludwig’s bustards, and 13 white storks in a three-year period.

In 2004, 54 blue crane carcasses were discovered near Graaff-Reinet in the Eastern Cape under 3.7km of distributi­on line.

Using computer modelling, the South African Crane Working Group estimated that an annual mortality rate of 150 adult blue cranes could reduce the eastern population of these birds by 90% by the end of the 21st century.

“From the figures quoted above, it is clear that power lines are a major cause of avian mortality among power-line-sensitive species, especially Red Data species … It is therefore imperative to reduce any form of unnatural mortality,” said the Eskom report.

In 2011, a team of avian researcher­s voiced concern about the future of Cape vultures in the Eastern Cape due to power-line collisions, electrocut­ion and other human impacts such as poisoning, land clearance for farming, and the traditiona­l medicine trade.

The researcher­s said the actual number of deaths is likely to be much higher than presently known, as most mortalitie­s from power lines go unreported.

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