Jay CabozBy Jay Caboz|November 1, 2020|11 Minutes|In Billionaire Tomorrow

The Strange Plastic Disks Saving Birds On The Wire

How do you stop power cuts and save endangered birds from themselves in one fell swoop? Well, it's simple. It takes a few thousand plastic disks swaying in the breeze.

Hundreds of plastic disks hang like washing on a powerline flapping gently in the breeze. The disks are white and are 5 meters apart as far as the eye can see. For some of the rarest birds in Africa they could be the difference between life and extinction.

There are two sides to this story. For the endangered Blue Crane, the national bird of South Africa, and Cape Vulture these small plastic disks could be their last hope of avoiding a fatal collision. For Eskom, the people that run the power lines, it could save power cuts and millions in repairs.

“By attaching these bird flight diverters, which is essentially a plastic clamp with a round plastic disk on the line you make the line a lot more visible for the birds. [Birds] can see the line from a lot further away and can alter their flight path and then the collision is avoided,” said Lourens Leeuwner, Wildlife and Energy Programme Manager at the Endangered Wildlife Trust (EWT).

The disks on the wire are part of the national power generator Eskom’s campaign to cut down the amount of electricity lost every year through bird strikes causing power cuts.

“For certain species, like the Blue Crane, attaching the disk would reduce collisions by 90%. For other species the figure is not as high but still effective,” said Leeuwner.

In the wild of South Africa, there are plenty of places where wayward birds can cause havoc with the country’s fragile electricity network.

Eskom has a 300,000 km distribution network in need of protection, says Kisahylin Chetty, Eskom Senior Environmental Scientist and project manager of the Eskom EWT Strategic Partnership. That’s 7 and half times around the Earth.

According to Chetty, Eskom is trying to protect these power lines from birds and claims no other power generator in the world has tried to do this on this scale.

This is how bad it can get: in KwaZulu-Natal, a Distribution Operating Unit had to inspect 6,134 km of powerline and had to bird proof 36,121 structures because they stood in the migration path. One false flap of wings could have spelt a power cut.

“In order to minimise the impact that we have on energy infrastructure on just 10% of those power lines, which we’ve calculated to be high-risk lines, it would cost Eskom somewhere in the region of R6.5 to R7 billion. This is a massive business initiative,” said Chetty.

One of the things making their work a lot easier is a data sensitivity map, representing decades of fieldwork. The culmination of this work resulted in Eskom and EWT being able to identify which power lines are likely to have a run-in with birds.

“Whilst the entire project itself is designed around the premise of trying to prevent blue crane and vulture mortality in terms of collision, I think what’s really valuable about this is there are a number of other species that stand to benefit just because of this initiative,” said Chetty.

This, they say, will help save more endangered birds. In the Eastern Cape, the maps have gone toward identifying the EWT’s Birds of Prey Programme creating a ‘Vulture Safe Zone’.

In the interest of birds of all shapes and sizes, independent power producers want to give Eskom a helping hand.

Four thousand two hundred bird diverters are set to be installed on Eskom power lines in high-risk areas advised by EWT. The donation was made by renewable energy producer BioTherm Energy, which owns two wind farms in South Africa, both of which have their own diverters already.

“We worked hard to design programmes aimed not only at zero loss to priority species, but that actually result in net gain wherever possible. We wanted to explore what we could do to achieve this aim, beyond on-site mitigation measures. It will prevent needless collisions by Blue cranes, Cape Vultures, and other raptors,” said Libby Hirshon, BioTherm Sustainability Director.

One of its wind farms, Excelsior Wind Farm, is found in a high-risk bird strike zone in the Western Cape, but the 4,200 bird diverters the company donated are destined for locations at the discretion of EWT.

They’ll need to make some careful choices. While the bird diverters are fairly cheap to manufacture, installing them is as costly as it is time-consuming. The ‘easiest’ method is using what they call a link stick. It looks like a pole vault and is a long fibreglass rod with a special attachment on its end that lets you clip the disk onto the wire and even if it’s live.

“It sounds simple but it depends on the terrain. If you have a span in a valley the link stick won’t reach. If it’s very windy it makes it very hard to control,” said Leeuwner.

If the line is too high to reach, their next step is bucket trucks.  But the bucket truck doesn’t reach far and can only put up three plastic disks at a time before they have to move on. It takes ages.

Then there are transmission lines which stand 60 meters above the ground. They need helicopters to put the bird diverters onto the line.

In order to minimise the impact that we have on energy infrastructure on just 10% of those power lines, which weve calculated to be high-risk lines, it would cost Eskom somewhere in the region of R6.5 to R7 billion. This is a massive business initiative.

- Kisahylin Chetty, Eskom Senior Environmental Scientist

“Once you put something up on a transmission line 60 meters in the air you don’t want that thing to fall off. You don’t want to have maintenance on that device, because then you need to deploy helicopters and all sorts of machinery to get it done. It’s a very robust device, it’s designed to last a lifetime of the line,” said Leeuwner.

Drones could be the answer to cutting the costs and making it easier to install. Leeuwner says that the EWT is currently applying for a commercial operators licence with the South African Civil Aviation Authority, which if it passes could help speed up the process and cut costs significantly.


“We started talking 3 years ago about a system whereby a drone can actually deploy these bird flappers onto the line. It takes away the cost element of a live line team, and you’re taking away the safety risks working on live infrastructure. We designed a magazine whereby 4 bird diverters could be attached and the drone would hoist it into the air and deploy the flappers,” said Leeuwner.

EWT needs to pass stringent flight safety tests. If it does the drones could attach up to 10 bird diverters in 30 minutes.

While the bird diverters can make a difference they don’t always work. Certain species of birds can’t see them.

“It’s got to do either with their visual fields or the way a species perceives colour. You have to look at how far into the UV spectrum bird species can see. How it is that that bird can see its day to day activities.”

The team says it is now experimenting with other models and shapes to see if they can come up with something better. The research continues on to look into future models that could be made of different colours and it is even experimenting with flashing UV LED lights.

“South Africa is the only country that has really done suitable tests, in terms of testing the efficiency of bird flight diverter models,” said Chetty.

As more bird diverters start flapping in the breeze surely the birds will be pleased.

Privacy Preference Center

Open chat
You can now access all our latest stories on your WhatsApp. Open the chat and send "Hi".

Want to give it a try? 😊