Sparrow-sized bat confirmed as Mozambique’s newest mammal

A small insect-eating bat has been confirmed as Mozambique’s newest species of mammal after more than a decade of intensive study by scientists who used near-invisible “mist nets” to catch their first specimens.  

The Namuli horseshoe bat is named for the horseshoe-shaped flap of skin on its face. This small insect-eating bat has been confirmed as Mozambique’s newest species of mammal, according to a study published in August 2022. © Mirjam Kopp

The Namuli horseshoe bat lives in threatened forests around Mount Namuli – Mozambique’s second highest peak – in the northern Zambezia Province.

The 13-year delay after first collection shows the rigour of the scientific processes that have to be gone through before an announcement of a new species can be communicated publicly.

In this case, the scientists studying the bat had to refer to specimens of its closest relatives in museum collections in South Africa, Malawi, Germany and Switzerland.

But the delay wasn’t all bad, said Julian Bayliss, one of the scientists behind the discovery. It did in fact aid the team: over the same period, improvements in technology to assess the DNA of the new bat species helped the scientists obtain irrefutable proof that the specimens they had collected were new to science.

“I think, even though it took so long to publish this paper, we got a much better paper,” Bayliss told RFI.  

To catch the bat, the scientists used traps and mist nets made of such fine material that they were able to evade detection by the bats’ sonar.

Scientist and lead author of the bat study, Michael Curran, fires a line into the canopy of the forest to hoist up a mist net. The technique was used to catch the Namuli horseshoe bat that lives in threatened forests around Mount Namuli, Mozambique. © Mirjam Kopp

Bats always remember

Horseshoe bats, which have brown fur and tiny black eyes no bigger than mustard seeds, are sparrow-sized and named for the horseshoe-shaped structures on their faces that are used for echolocating – or sending out soundwaves – to help them to navigate or catch flying insects.

“The thickness of the net is thinner than the ability of the bat’s sonar to echolocate and decide and determine there is something in front of it,” explained Bayliss.

The nets work most of the time. Sometimes, however, they accumulate moisture on the filaments, or blow in the wind. Bats are then alerted to the presence of a trap.  

“If they do detect it, the next night they will go around it automatically,” Bayliss said. “You really have to catch them on the first night or the second night.

After that they have picked up and they remember that there is a net there and they’ll fly around it and avoid it.”

The traps have to be monitored at all times. If captured bats are left too long in the nets, they can bite through their own wings trying to escape.

Harp traps were also used by the team. These are devices that catch bats as they fly through fine, vertically-strung fishing lines and fall down unharmed into collection bags beneath.

Saving the forests

Now that the difficult task of collecting and describing a new species is complete, the challenge will be to protect Namuli's remnant patches of moist evergreen forest. An estimated 24,000 people live around the mountain, which rises to 2,400 metres at its summit.

The human communities depend on the mountain’s resources for survival. Forests are being felled to grow small patches of potatoes and other crops.

Valleys surrounding Mount Namuli in Mozambique once supported dense forest that has now mostly been turned into agricultural land. © Michael Curran

The Namuli horseshoe bat does live in places other than Mount Namuli. They've been recorded on the Nyika plateau in northern Malawi, and in southern Tanzania.

But by naming the species after the Mozambican mountain, Bayliss and his colleagues hope to draw the world’s attention to the threats it faces.

"Since 2009, Namuli has suffered a significant loss in its wet forest," the authors state in their bat study published in the journal Acta Chiropterologica. “At current rates of loss, the forest would disappear entirely by 2025.”

• Global forests pledge will fail without urgent action, report warns

The forests are home to other important species including a bird only found in Mozambique – the small warbler-like Namuli apalis. But while bats and apalises have wings to move to other remnant forest patches; Namuli's sedentary species like chameleons and snakes have no other place to go.

Local conservation groups are working to slow down forest loss. One group, Nitidae, reports that annual deforestation around Mount Namuli slowed to around 2 percent in 2020, from more than 8 percent between 2015 and 2018.

Mount Namuli in Mozambique rises to 2,400 metres at its highest peak and is home to the Namuli horseshoe bat. © Michael Curran