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After wriggling gingerly into a damp, cool cave, Raúl da Silva Armando Chomela waits for his eyes to adjust. Donning latex gloves, a helmet fitted with a headlamp, and a mask to protect his lungs from fine particles and bacteria, the molecular biologist from the Mozambican port city of Beira gazes into the shadowy recesses for signs of bats.
He has spent two years in these claustrophobic spaces studying the winged mammals and their excrement. “Guano is far more than just bat droppings,” he says. “If I had to describe it in one word, I’d say ‘ecosystem’.”
Developed over time from bird and bat faeces, guano is a rich, potent, organic material that is home to cave-dwelling beetles, frogs and salamanders.
Caves are little worlds of their own. Everything smells, looks and feels different, with organisms and microbiomes that have evolved to exist under very niche conditions without sunlight.
This is just one of more than 30 caves in and near Gorongosa, a sprawling 4,000 sq km (1,500 sq miles) national park in central Mozambique, one of the most biodiverse regions in Africa.
The work Chomela does is not for the faint of heart. He regularly squeezes into small, dark spaces or lowers himself down a ladder or rope into an unknown environment with strange inhabitants. Getting stuck is always a possibility.
These underground, honeycombed networks cover 183 sq km, according to the park’s science department. While no data exists on how many of the 100-plus species of bats found in Gorongosa live here, Tombo Aphale 5 – one of the most studied caves, with an active archaeological excavation – hosts more than 10,000 bats, says Chomela.
Gorongosa was founded in 1960 by the colonial Portuguese government. But biodiversity and conservation were not a priority for the Marxist-leaning Frelimo party (Frente de Libertação de Moçambique), which came to power in 1975 after a decade-long war of independence.
Only two years later, the park became a battleground in the bloody civil war launched by the guerrilla forces of Renamo (Resistência Nacional Moçambicana), created by Ian Smith’s white-minority government in Rhodesia and later supported by apartheid South Africa.
The Renamo guerrillas found refuge and fuel in the bushes, hunting down and consuming anything they could get their hands on: elephants, buffalo, waterbuck, hippos, even southern pouched rats. By the time the war ended more than 15 years later, 95% of the wildlife had been obliterated – including nearly all the area’s 5,500 hippos – and many feared the animal kingdom would never fully recover.
The immense trauma inflicted upon local people, survivors of a protracted war who suffered forced recruitment and human rights abuses from both sides, remains perceptible in the identities of present generations.
Against such odds, decades of careful environmental efforts – often spearheaded by international organisations but increasingly incorporating Mozambican researchers and communities – have resulted in one of the most satisfying tales of successful conservation in Africa.
Among them is the Paleo-Primate Project (PPP), a partnership launched in 2018 between Oxford University and Gorongosa national park led by Susana Carvalho, a primatologist and paleoanthropologist.
The project brings together international and local researchers and students of archaeology, ecology and geology. “[Gorongosa Restoration Project] is the largest employer in the region and an important factor for economic stability,” Carvalho says.
Chomela began his journey at Gorongosa as a biodiversity lab researcher in 2022 before joining PPP in 2025. His interests range from using environmental DNA to reconstruct the park’s ancient history to metabarcoding – a cutting-edge molecular technique to determine the species composition of DNA samples of primates and bats. A first-year doctoral student at the University of Porto in Portugal, his research is attached to the EO Wilson Laboratory in Chitengo, in the heart of Gorongosa, where he heads the genetics laboratory.
Chomela, 28, is at the forefront of several highly niche fields revolving around the impact of economic activities and climate breakdown on Gorongosa’s ecosystem, including the role of bats.
“We know that bats feed on insects – including mosquitoes that are malaria vectors – and pests, which protects crops,” Chomela says. “That’s why we’re focusing on understanding exactly what constitutes bats’ diets, and the rate at which guano is produced.”
Many local people – young men in particular – know these caves like the back of their hands, having grown up playing in them before harvesting guano to eke out a living. João Lorenço Daoce, 29, became the community leader of Inhaminga, a town near the caves, after his father died last year and serves as a cave guide for members of PPP. “He knows the easiest, safest way to get to most caves,” Chomela says.
The two men have developed a strong relationship and Daoce is beginning to share his new viewpoint on bats and their benefit to farmers with his neighbours.
Mozambicans are among the most impoverished people in the world. The southern African nation is ranked on the UN’s human development index, despite its wealth of diamonds, rubies, graphite, gas and other natural resources. Harvesting guano is one of the few reliable ways to earn cash in rural communities.
Chomela estimates that, on average, harvesters make 200 meticais (£2.33) for every 50kg of guano – which is rich in nitrogen, phosphorus and potassium – collected and sold as agricultural fertiliser, mainly for sorghum, beans and maize. “Locals know guano is a very nice fertiliser and put it in their machambas [farming plots],” Chomela says.
But without a measured collection system, the guano can be rapidly depleted, damaging the caves’ biodiversity and the community’s income.
“When they see the guano, they see money. But guano is the thing that guarantees stable environmental conditions in caves, from the 100% humidity or 50C [122F] temperature that some bats need to survive,” says Chomela. “Overharvesting will compromise the composition of a cave, making it sterile. Then the harvesters will move on to the next cave.
“We want a scientific base to convince the community, and society in general, of a sustainable way to harvest guano using less damaging techniques without disturbing the bats too much,” he says.
To metabarcode, Chomela catches and tags a bat before keeping it in a sterile bag until it releases droppings. These samples provide a wealth of information: what the bat consumes, sex ratios and the presence of parasites and pathogens.
He hopes that results from this DNA study of bat guano, which he is working on with two other researchers, will help people living in these remote regions become protectors of bats themselves. “For instance, if we can show that bats feed on pests that bother farmers’ crops, [farmers] will be friendlier towards the bats,” he says.
Although humans have always lived alongside bats, understanding of their role in the ecosystem is limited. Traditional beliefs often regard them as bad omens or mistakenly blame them for diseases. “There are those who believe that if bats come to your home, someone will die,” says Chomela. “It’s important to show that this isn’t the case.
By presenting scientifically backed evidence to community members, he hopes to convince locals – the guardians of these caves – of the importance of coexistence.
