Dear rat, did you ever know that you're my hero?

Daniel is on a mission. Somewhere in the rubble and debris that surround him inside this wrecked building in central Tanzania, a survivor is trapped. Daniel is determined to find him. He navigates the wreckage like a pro, just as he’s been taught during his long months of search-and-rescue training. Moving methodically from room to room, he peers into dark corners obscured by debris and scans behind what’s left of the furniture. The job isn’t easy, and for his lifesaving work, he’s paid peanuts. But that doesn’t bother him. Daniel is, after all, a rat. And peanuts just happen to be his favorite food.

Daniel is one of a cohort of elite "rescue rats” currently enrolled at the Apopo training centre in the Tanzanian town of Morogoro. Since the early 2000s, Apopo’s African giant pouched rats have been using their acute sense of smell to sniff out landmines and detect TB in sputum samples. Now, they look set to become search-and-rescue specialists too.

Today’s operation is a training exercise. The “survivor” is, in fact, one of Daniel’s trainers, and the “disaster zone” has been carefully constructed to simulate a building struck by an earthquake or tsunami. It takes Daniel just two minutes to locate his target, a man in a blue coveralls slumped against a wall.

Daniel stands on his hind legs and uses his front paws to pull a switch attached to his custom-made rescue vest, sending a signal to his handlers outside the building that he has successfully completed his mission. Then he retraces his steps through the rubble and exits through a hole in the wall.

“In search-and-rescue operations, every minute counts, but canine units can’t penetrate inside the debris, and camera probes and robots can only penetrate to an extent,” says Danielle Giangrasso, a behavioral research scientist and the head of Apopo’s rescue rat program. “The idea is to have rats that can go in and use their sense of smell to conduct a guided search within the debris. They're small, they're agile and they're very curious. So the goal is for them to complement existing search strategies.”

African giant pouched rats are particularly well-suited for the task. Measuring up to 3 feet long from nose to the tip of the tail, and weighing up to 9 pounds, they have the stamina to search over wide areas without becoming fatigued yet are still small and agile enough to navigate cramped spaces. Unlike dogs, they’re easily transferable between handlers. And they have a far longer lifespan than other types of rats. After a year in training, they can have a working career of around seven years. Then they live out their days in comfortable retirement at Apopo’s training complex in Morogoro.

The complex sits on the grounds of an agricultural university in a compound hemmed in by lush trees. During a recent visit, monkeys leaped from branch to branch, occasionally careening over the buildings’ tin rooftops, while Apopo's roughly 300 rats went about their business. A group of juvenile mine-detection rats scoured a rectangle of earth in search of capsules containing TNT. Nearby, several older rats, now retired, snoozed in clay pots in their cages. Others enjoyed scheduled recreation time in a series of custom-built play enclosures. And in a garage behind the car park, the youngest rats, at just a few weeks old, rummaged through the grimy contents of a workbench during a “socialization” session designed to habituate them to the world of humans.

The training is reward-based. When a rat correctly identifies its target, be it a buried landmine, a positive TB sample, a human being or an illegal wildlife product, it signals to its handler, who uses a clicker to let them know when they’ve been successful. The rat is then rewarded with a treat, usually a banana-avocado smoothie or a handful of peanuts. (Each year, Apopo’s giant rats go through some 25,000 bananas, 6,200 avocadoes and just over a ton of peanuts.)

Apopo isn’t the only organization training rats, but it claims to be the only one whose rats are already working. And it is certainly the first to attempt to train them in search and rescue.

For the rescue rat handlers, it’s been a learning experience.

“They’re so clever,” says Giangrasso. “You always have to stay five steps ahead of them. And there are so many different things to consider.”

The team has to constantly reconfigure the rats’ training area so they can’t simply operate from memory. To make it more realistic, they incorporate the sounds of drilling or machinery. They use different actors to play the “survivor” so the rats learn that any human is a target, not just those of a particular ethnicity, age or gender. They’ve had to teach the rats to discriminate between the smell of humans and human-associated objects like clothes and shoes. And they carry out “distractor training” to teach them to ignore tempting smells and stay focused, no easy task amid the sensory overload of a destroyed building.

“We need to know if they’re really going to stay motivated for the target or if they’re just going to go and have a great time in some collapsed kitchen,” says Giangrasso.

Producing the perfect rescue rat isn’t only about training. Like humans, each rat has its own personality, its own strengths and weaknesses. Ideally, the team wants individuals that are active and curious enough to make effective searchers yet disciplined enough to stay on target and return when called. To this end, the trainers have been collaborating with researchers from the University of Bristol in the U.K. to better understand the personalities and preferences of their rats.

“A lot of people view a rat as just a rat,” says Giangrasso, who, like most of Apopo’s trainers and researchers, has her own personal favorite among her students. “But there are a lot of personality differences. There are some rats who just search in a different way, who seem to be more dialed in and seem to be more methodical in their thinking. For me, that rat is Daniel.”

Daniel is now in the final stages of his training program in Tanzania. Later this summer, he and five of his colleagues will fly to Turkey, a hotspot of tectonic activity, where they’ll join up with a local search-and-rescue group for advanced training and trials. If all goes well, Apopo trainers hope the rats could soon be ready for deployment in real disaster zones.

In the meantime, the organization is collaborating with researchers in the Netherlands to produce a miniature communications “backpack” for the rats to wear.

“After proving the rats were able to find people, we thought, what if we could also get images and sound out of the building,” says Saidi Mshana, a research supervisor for Apopo. “It’s like we’re adding technology to the rat.”

The team recently started testing the latest prototype. Weighing just over 3 ounces, the backpack contains a tiny camera that will send a livestream to rescuers outside the rubble, and a two-way microphone to enable them to communicate with survivors.

“We’re constantly refining existing areas of operation,” says Mshana, who has seen the organization expand rapidly since he began working there 15 years ago. “And also constantly trying to find new ways for rats to save lives.”

Since conducting their first landmine-detection tests in Mozambique in 2003, Apopo's rats have helped find over 160,000 mines and other explosives, and its TB-detection rats have screened more than a half-million patients. The organization is also in the final stages of a project to help Tanzanian port authorities find smuggled wildlife products, such as ivory and pangolin scales, and has been in discussions with a U.S. oil company looking to use rats to identify soil contamination for environmental cleanup operations.

“People think of us as a rat university,” says Christophe Cox, Apopo’s CEO and co-founder. “We’re always getting more requests: Can you do this? Can you do that? How much do they cost? When can they start? But it’s not like we’ve got them lined up on shelves ready to be shipped off.”

The requests are varied. A Dutch NGO recently got in touch to ask if the rats could detect underground water leakages. A national customs agency wanted to know if they could sniff out shark fins. Others want to use the rats for detecting salmonella, brucellosis (a disease that mainly affects livestock) and cancers of various kinds. One American organization wanted to know if they could assist with finding decomposing bodies.

The simple answer is almost always yes. Rats, says Cox, can be trained to identify virtually any smell. But setting up each new program is a major undertaking, and there’s only so much one small nonprofit can manage. Funding is often an issue, as are the logistical difficulties of securing the vast number of samples needed to train the rats. Another challenge is the general public’s negative perception of rats. As one staff member put it, “We’re cognizant that not everybody loves rats as much as we do.”

Rats could provide a useful screening service at airports, Cox says, but he doubts airline passengers would tolerate their bags being sniffed by the rodents. In the context of search-and- rescue operations, the team has pondered what effect it could have on an already traumatized survivor trapped beneath rubble when they’re approached by a giant rat wearing a backpack.

“We still have to work on people's conception of rats and how they just view them as dirty sewer animals,” says Giangrasso, who nevertheless hopes that in the future, rapid reaction search-and- rescue rat units could become as normalized and accepted as their canine counterparts.

“We see search-and-rescue dogs as normal, we don't usually bat an eye about that,” she says. “It would be nice for rats to be recognized in the same way. I think we’ll get there, it’s just a matter of when.”

Tommy Trenchard is an independent photojournalist based in Cape Town, South Africa. He has previously contributed photos and stories to NPR on the Mozambique cyclone of 2019, Indonesian death rituals and illegal miners in abandoned South African diamond mines.