Source: MRI Whale Unit.
Source: MRI Whale Unit.
  • SA Scientists are now using drones to help study the changing body conditions and behaviour patterns of southern right whales.  
  • The technology is not only helping to reveal new perspectives, but is also more cost-effective and non-evasive.
  • Up to 2009 you could expect to see about 400 to 450 females with calves and around 300 to 400 unaccompanied adults. After that the numbers became erratic and started declining dramatically.
  • Food shortages mean southern right whales are getting thinner, have less energy to calve, and are changing their foraging habits – all worrying signs of changing climates. 
  • For more stories go to 

South African scientists have taken to using drones to tackle the critical questions surrounding South Africa's disappearing southern right whale population.

A partnership between the Endangered Wildlife Trust (EWT), that has a licence to operate drones for conservation, and the University of Pretoria Mammal Research Institute's Whale Unit are now using drones to study the mystery behind the declining numbers, changing body conditions, and behaviour patterns of southern right whales (Eubalaena australis).  

"Drone technology has revolutionised the way we conduct our research. Using drones, we can gather overhead images of right whales every year, allowing us to track the variation in their body condition over time in a very cost-effective manner, and collect additional photo-identification data, which allows us to assess the residency time of individual animals on the South African breeding ground," says Dr Els Vermeulen, Research Manager of the MRI Whale Unit based out of Hermanus.

How do scientists identify whales?

Southern right whales are characterised by a broad back with no dorsal fin, a long arching mouth that begins above the eye and distinctive white markings on their heads. These markings are called callosities and are unique to each whale – similar to fingerprints in humans. Callosities are home to tiny crustaceans called cyamids or whale lice, which gives the callosity a whitish colour. The unique pattern of the callosities enables researchers to identify each whale individually which is key in monitoring their movements and progress.

Source: University of Pretoria Mammal Research Institute’s Whale Unit

On any given day you can find Vermeulen hard at work investigating the South African population of southern right whales, a database that has been going since 1969. With experience in marine mammal research that spans over two decades, she says drone technology has been a game changer. Not only helping to reveal new perspectives when observing these gentle giants but also creating a more cost-effective and non-evasive way to do research. 

"An aerial view of these animals reveals more information on their behaviour than viewing them from a boat. It is truly a unique piece of technology that can be adjusted for various research projects, and we aim to apply it in much more of our research going forward."

Prior to drones, accessing this sort of imagery would have cost a pretty penny, as much as R50,000 an hour, from a camera mounted on to a helicopter. But thanks to drones and their cameras, gathering this information comes in at a fraction of the cost. 

The work can all be done thanks to the EWT that obtained its Remotely Piloted Aircraft Systems Operator's Certificate earlier this year, after three years of waiting. Since then the conservation group has hit the ground running having involved itself in a number of projects including using drones to install plastic bird diverters on to telephone lines, to prevent birds collisions.

"We are really excited to assist the Whale Unit with this important work by providing a licensed drone pilot, ensuring all work can be conducted in accordance with permit conditions. This research is a perfect example of why the EWT started the Drone project: to support conservation work across the country through affordable aerial solutions," says Lourens Leeuwner of the EWT Drone project.

Photo by Anke Nel. Source: MRI Whale Unit.
Photo by Anke Nel. Source: MRI Whale Unit.

The latest partnership with EWT will go a long way toward adding data the Whale Unit has been compiling since 2019, when the research started into the worrying signs of southern right whale number decline and changing feeding behaviour.

"In normal times up to 2009, we would have in the ballpark of about 400 to 450 females with calves and we'd have around 300 to 400 what we call unaccompanied adults, which would be males and the females that are not calving that year," says Vermeulen.

"But since 2009, that number of the unaccompanied adults has dropped dramatically to maybe 30 to 40 animals - that's a tenfold drop. And then the number of females with calves have dropped very drastically after 2015. In 2016, we had 55 females with calves on our coast."

The reason they think the numbers have dropped is because of food scarcity from changing climates.

"Their main food source is krill (a small shrimplike planktonic crustacean), and current research indicates that changes in ocean temperatures affect the abundance and location of these and other creatures, with far-reaching environmental consequences.

"From skin samples, we compared foraging strategies from now compared to the late 80s or early 90s and we see a very clear shift in feeding location. Southern right whales are feeding more North than normal. What exactly the diet is, we don't know. But there's a clear shift in it."

Photo by Anke Nel. Source: MRI Whale Unit.
Photo by Anke Nel. Source: MRI Whale Unit.

Another consequence of the food shortages is females are now calving once every four to five years, instead of an average cycle of three years. This is because the whales are not getting enough nutrition and are simply too tired to migrate. They can tell this by comparing average sizes using images in their database where there has been a 24% decrease in body condition of lactating females from the late 80s to 2019, says Vermeulen. 

"We are able to identify each animal that we measure, and we take a biopsy sample at the same time meaning now we have skin samples, blood samples, an idea of this as well as body condition and now with the combination of those things we can do a lot."

The drone imagery can also go toward helping provide a global picture of what is going on in the ocean. The Whale Unit shares the data to comparative studies with images of southern right whales taken in Australia and Argentina.

The Whale Unit and EWT will release findings of their latest research at the 2nd Drone users conference: Conservation & Agriculture to be held from 29 November 2021 to Wednesday, 1 December 2021 in Elsenburg, Stellenbosch, Western Cape. 

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