HORIZONS
SEARCH AND RESCUE RATS ARE BEING TRAINED TO FIND EARTHQUAKE SURVIVORS AMONG THE RUBBLE
Researchers have successfully trained rats to detect landmines, sniff out tuberculosis and even drive cars, but their next challenge – to find survivors in collapsed buildings – could be their bravest yet
WHY RATS?
They can contribute something that the other technologies can’t, at least for the areas we work in. Their sense of smell and their trainability is on a par with dogs. But it’s the rats’ small size that really makes a difference.
At APOPO [an acronym from the Dutch for Anti-Personnel Landmine Detection Product Development], we work with the African giant pouched rat (Cricetomys ansorgei). We taught them to detect landmines because they’re too small and too light to trigger the devices. We’re teaching them to detect the scent of illegally smuggled wildlife in shipping ports because they can reach the containers stacked up high on top one another.
For my research in training rats for search and rescue, the main reason is that they can get into the small, tight areas of a debris site. Search and rescue dogs typically just go around debris sites, whereas we’re hoping the rats can actually go inside, through all the rubble, because they’re so small.
Any application of them has to be in response to a humanitarian challenge, and it has to require the unique capabilities of our rats to help. If there’s already [other] effective technology available, and it’s affordable, we’re not going to train our rats just for the fun of it.
HOW DO YOU TRAIN A RAT TO SEEK OUT BURIED SURVIVORS?
We use positive reinforcement to train them on a basic sequence of behaviour. So, here it’s to search for a human, indicate to us that they’ve found them, and then return to where they were released.
[Training] starts off in a really basic environment: a small, empty room. Then we gradually expand and increase the complexity so it becomes more like real life. We can start adding in debris and making the training area look more like an actual collapsed building site.
The search and rescue rats are trained in rooms that are gradually filled with debris to increasingly resemble the site of an earthquake 
WHAT HAPPENS WHEN ONE OF THE RATS FINDS A SURVIVOR?
They need to trigger a switch that makes a noise. Currently, we get them to wear a vest that has a little ball on its collar, a ball containing a microswitch. The rats are trained to pull the ball when they find someone, which triggers the microswitch and lets out a beep.
Pulling the ball isn’t a natural behaviour for them, but they can be trained through a process we call ‘shaping’. We start by putting the vest with the ball on the rats. They’re naturally quite curious, so when they have the ball hanging there, you can see they’re kind of like, ‘What is this?’
In the beginning, we’re just reinforcing them for touching the ball at all. Then, as is standard for shaping, you would stop reinforcing for just touching so they realise, ‘Oh, I’m not getting reinforced any more’. Then they’ll try harder [to get the reward].
That typically leads them to pull on the ball and, when they do, we have to really quickly reward them, so they know that’s the target behaviour. Then, in a similar way, we can continue shaping until they’re pulling it for two to three seconds, so it’s a really strong signal to us.
Of course, in the field we won’t be able to see the rats, or hear them.
So, we’re working with a group of engineers to develop a multi-function backpack that’s linked up to our computer so that we’ll be notified when the rats pull the ball. We’ll be able to know exactly where they are, because the backpacks should have a location transmitter, as well.
HOW CAN THEY TELL THE DIFFERENCE BETWEEN THOSE WHO ARE ALIVE AND THOSE WHO AREN’T?
We’ve talked about this a lot, because we’ll only do the training with living people. However, dog trainers have told us that the odour profile of a person that’s alive, compared to a person that’s dead, is very different.
Dogs can tell the difference between a living and deceased person from around three to four hours after death.
We thought that maybe we’d have to train the rats using some sort of smell that we might be able to get our hands on – it’s hard to know what to call it, but, basically, we would need the smell of death.
But the dog trainers have told us we don’t have to do that, because the odour change between living and dead people is so different that it’s not a problem.
WHEN WILL THESE RATS BE PUT TO WORK IN THE FIELD?
We just started training in August 2021 and we still have to run training trials outside the research environment. We’re working with a search and rescue group called GEA, who are based in Turkey, a country that’s prone to earthquakes. We’re hoping that by next year we’ll be able to take the rats to Turkey for trials there, but in terms of going to real disaster sites – real collapsed buildings – it’s very difficult to tell.
“For these projects it costs, on average, around €6,000 to fully train one rat so they’re ready for operations”
APOPO’s landmine research started in 1998, and its first operational trials were in 2003/4. Our tuberculosis detection research began in 2003, and the rats began operating in 2007.
For these projects it costs, on average, around €6,000 [approximately £5,175] to fully train one rat so they’re ready for operations.
We’re currently training seven for search and rescue, although they have to take turns using the backpack – we’ve only got one at the moment!
DR DONNA KEAN
Donna is a behavioural researcher at APOPO, training rats to search for and rescue earthquake survivors.