article / 18 March 2021

Interview: Protecting Vultures with Telemetry

In this interview with Dr. Corinne Kendall of the North Carolina Zoo, Dr. Kendall shares  how telemetry studies can help prevent vulture poisoning in East Africa, the conservation technology she uses in her work, and the challenges she faces in protecting endangered vultures from poisoning hotspots.

Many species of vulture are endangered and face extinction, with poisoning standing as one of the biggest threats against them worldwide. Because vultures are scavengers, feeding on carcasses, they are uniquely at risk for ingesting a wide variety of toxic manmade substances, including lead, as in the case of the California Condor.

The most famous instance of vulture poisoning is undoubtedly the case of diclofenac in South Asia. The anti-inflammatory drug, given to cattle, proved fatal to vultures feeding on their carcasses, even in small doses. Diclofenac caused the deaths of millions of vultures, bringing them close to extinction.

This loss of vultures caused a health crisis. Without these scavengers, carcasses were left rotting and spreading TB, anthrax, brucellosis, and foot-and-mouth disease. Feral dogs moved into the ecological niche left vacant by the vultures, and the stray dog population exploded, causing an increase in rabies.

Although banning the veterinary use of diclofenac slowed and, in some cases, reversed vulture declines in South Asia, vultures worldwide are still vulnerable to poisoning via the carcasses on which they feed.


WILDLABS spoke to Dr Corinne Kendall, of North Carolina Zoo, who currently works in Tanzania where vultures are being poisoned under very different circumstances. Using telemetry and collaborating with government and non-government partners on the ground like Wildlife Conservation Society, she identifies poisoning hotspots to better understand the drivers of vulture poisoning, and how to prevent it.

Read on to learn from Dr. Kendall about how telemetry studies can help prevent vulture poisoning in East Africa, the conservation technology she uses in her work, and the challenges she faces in protecting vultures.

Want to know more about using telemetry to monitor birds? Watch our Tech Tutors Season 2 episode, “How do I choose the right tech for my bird monitoring project?"

Vultures and Telemetry with Dr. Corinne Kendall

What is the current situation with vultures in East Africa? What’s happening, and what are the major threats?

Poisoning is the number one threat to African vultures. Although vulture poisoning doesn’t happen every day, it's hugely catastrophic for the birds, even as a very infrequent activity occuring just a few times a year. A single poisoned carcass can kill 100 vultures. We’ve learnt from movement data that a carcass brings in birds from a large area, so poisoning has a wide-reaching effect across the landscape.

There are a few drivers of this poisoning, one being human-wildlife conflict - that's the one I've dealt with the most often. A large predator kills someone’s livestock, and in response, they put pesticides on the dead animal to kill carnivores when they return to the carcass. The reality is that this technique isn’t particularly effective; sometimes it doesn’t kill any carnivores at all. But often it does kill the vultures and other scavengers that are attracted to the carcass.


The second driver, which has been on the rise in the last five years, is “sentinel poisoning”. Sentinel poisoning describes when poachers kill vultures to prevent them giving away their position to rangers while the poachers butcher their animal.

The third motivation is traditional medicine in which vulture heads and feet are used, particularly in West Africa, but also Tanzania and South Africa. Unfortunately, the movements of these body parts in the trade aren't very well understood yet.

When we first started this research in Kenya, we didn’t know how bad poisoning was. Using telemetry studies and roadside surveys, we established that vulture populations are declining rapidly due to poisoning. Now we’re continuing this work in southern Tanzania to understand how bad the poisoning crisis is there, where it’s happening, and who’s doing it.

So how exactly are you using telemetry tech to gather information on poisoning events, and how does this inform management plans?

It was estimated that less than 3% of carcasses in Southeast Asia would need to be contaminated to have a significant effect on the vulture population. When you poison, you're bringing in birds from a very large area, potentially hundreds of kilometers. 

Poisoning happens infrequently, but when it occurs it's catastrophic. Even though it results in the death of hundreds of animals, its illegal nature means it isn’t necessarily discovered. Telemetry allows us to follow a set of birds’ movements across a landscape. When a bird dies, we get mortality alerts from the telemetry, enabling us to figure out where the poisoning happened.

Right now, we have a PhD student working on figuring out how many birds we need to tag over what area to catch all the poisoning activity within the landscape. Although, based on what we do know about vultures’ foraging ecology, even with a handful of tagged birds, you’re still able to understand what’s happening on a large landscape scale.

Birds, and vultures in particular, are of course very mobile creatures. What has your research revealed about the usefulness of national parks for vulture protection, seeing as they are moving in and out of park boundaries?

This is a big question that we’re working on through a huge, near continent-wide collaboration project. In India, they've established “Vulture Safe Zones," areas where they can ensure all carcasses were uncontaminated with diclofenac. But it’s hard to say if this could be applied in regions in Africa, where the poisoning is often intentional and the birds range over huge areas.

What we’re trying to do is identify the poisoning hotspots, respond to them more quickly, and ensure there are laws in place against this activity, as well as the prosecution to follow through on those laws.

What conservation action comes out of identifying a poisoning hotspot?


We’re been working closely with the Ruaha Carnivore Project and other lion conservation groups to figure out where the conflict is happening. Based on this, we can identify communities where work is needed to address the conflict by setting up better bomas and Lion Guardian systems, thus empowering the community to better protect their livestock.

What are your biggest tech challenges?

Working in southern Tanzania, one of the big challenges is that we're limited to satellite telemetry. When I did my PhD in Kenya, I used GSM as the coverage in southern Kenya is quite good. You get a lot more data from GSM, and you can have the data sent to you, potentially multiple times a day because it's just a text package. Because you're only paying for a cell phone package, it's cheap (about a few hundred US dollars a year to download your data). So, where you can use GSM, that's definitely the way to go. 

But in southern Tanzania, the cell phone coverage isn't that good. We use Microwave Telemetry, Argos 70 grams solar-powered satellite tags fitted like a backpack, so the unit sits right in between their wings. I have to say the tags themselves are amazing, and we’ve had tags that have lasted more than three years. But we are limited in terms of data and downloads - we only get hourly data, downloaded once a day.

One of the strengths of the satellite units we've been using are the activity sensors, which help us establish if the bird is alive or not based on the movement and tilting of the unit. That's been helpful for vultures because when they're at a carcass, they might spend two or three days sitting in the same place. The activity sensor can still determine if they’re alive, even though they’re not flying around. A battery monitor tells us if the solar-powered battery is declining, which often happens when a bird is dead and flipped over.  Those two major indicators about mortality have been major strengths of the tool. 

The biggest challenge for us is not technology, but rather the scale and ruggedness of the landscape. When a bird dies, we want to get to it quickly, but realistically it often takes days, sometimes even weeks, to get to wherever the bird is. Ruaha National Park, including surrounding protected areas, is about 50,000 square kilometres. There isn’t a great road network, and heavy rains can disable the road network that does exist. So even though the tech is good enough to tell us where to go, our biggest challenge is actually getting there.


One of the great partnerships we have is with the Wildlife Conservation Society, who have helped us with some of the telemetry work, and also provided aerial support. That makes a huge difference in enabling us to check out possible dead vultures more rapidly. There are a lot of people thinking about real-time aspects of telemetry, and I think it's really exciting, but at least for us, we’re still limited by the infrastructure in the places where we work.

How do you manage bird recovery when vultures fly across borders?

We had one bird fly from Tanzania all the way to South Africa, travelling over 2000 kilometres! You just don’t know where they’ll end up, or where they might die. Everything comes down to partnerships. We work with the Tanzanian national park and wildlife authorities, and reach out to other conservation partners in northern Tanzania and southern Kenya, creating a wide vulture-recovery network throughout the region. Kenya also has a big Whatsapp group that brings everybody together to communicate.

Do you have any lessons on using conservation tech for our community?

I learned during my PhD that the cheapest, newest product is not necessarily the best.

I had one bad experience where I bought a particular product due to its affordability, because I could then buy many more units than if I’d gone for something better established at a higher price point. Many of the units only worked for a few months before failing due to the kinks in the tech not being worked out yet. It was really frustrating to spend so much time tagging birds and then not get much information, because we went for the newest coolest thing that wasn’t well-tested yet. I’ve become a lot more cautious with the tech I use since then.

What tech developments would you like to see in the near future?

Like anyone using telemetry, I’d like tech that is smaller, longer lasting, and collects more data. More regular downloads and cheaper satellite fees would be great, but honestly, for our purposes we have enough on the tech side. It's the real-world aspects that are limiting. The Icarus Project is a great effort to bring down the costs of data download for telemetry. Once those kinds of projects progress, they're going to be revolutionary.

Thanks to Dr. Corinne Kendall for sharing her work with us. All featured photos are from Dr. Kendall, and the North Carolina Zoo on Twitter.

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