Expedition confirms less than 750 rare Cuban bats left in last cave on Earth

Nail varnish helps ZSL EDGE conservationists calculate numbers of Cuban greater funnel-eared bats for first time.

One of the world's rarest bats is confined to a single cave in Western Cuba and in urgent need of conservation attention say ZSL conservationists, following a daring expedition using a unique method of counting in the form of a 'bat manicure'.

Photo - close-up of a small light brown bat held in a gloved hand
Cuban greater funnel-eared bat

Less than 750 of the rare Cuban greater funnel-eared bats (Natalus primus) remain in a singular cave on the peninsula of Guanahacabibes in Western Cuba, as revealed in the preliminary results from the species' first population estimates by ZSL's EDGE of Existence programme.

Needing to identify individual bats, the researchers employed a low-tech but effective method for safely marking the bats – they used four different nail varnish colours to paint the bats' 'nails' enabling them to create thousands of combinations for unique markings to identify each one, while being completely harmless to the bats.

Previously declared as Extinct – the Cuban greater funnel-eared bat was rediscovered in 1992 in Guanahacabibes, in the cave known locally as 'Cueva la Barca' by a group of Cuban scientists who heralded the species as "back from the dead". 

Fossils found nearly all over Cuba, as well as on Isa de la Juventud, Grand Cayman and various islands in the Bahamas allude to the species once being widespread during the late Pleistocene (11,000 y. ago), but it now only occurs in the last remaining tracts of Cuban lowland forest. 

Though the cause of the mass population decline is unknown, funnel-eared bats have a naturally high vulnerability to extinction due to their specific habitat of hot caves. The Cueva la Barca population are now threatened by human intrusion and collapse of their cave roof due to thermal instability – with climate change posing a significant risk, further exacerbating the issue.

Photo - conservationist sat on cave floor, applying nail varnish to a bat
New nail colours for male and female Cuban bats

Jose Manuel De La Cruz Mora, ZSL's Segré-EDGE Fellow, based at the Natural History Museum of Pinar del Río explained: "The story of the Cuban funnel-eared bat really resonated with me as it reiterates the absolute need to ensure underappreciated species like bats, don't become lost to scientific history, simply because we forget to look.

"Though marking bats is very challenging and it's typically done using necklaces, arm rings or wing punches, this can sometimes alter behaviour. As the remaining population of the bats were so small and understanding their biology is fundamental to our research – we wanted to keep things as natural as possible, apart from their brightly coloured nails of course.

"It was time consuming giving each bat an individual manicure, but it's an incredible privilege to get up-close to this amazing animal – and to discover more about them made all those hours painting their nails worth it! 

"Bats around the world are one of the most threatened group of animals due to destruction of their roosts, disease and even hunting – but they provide an enormous ecosystem benefit to humans. By keeping insect populations down, they reduce the chance of disease risk and pests on farmers' crops.

"As they're very picky about where they roost – they're particularly vulnerable to human disturbance, but now we have a rough estimate of how many are left, we can plan the best conservation action – including local community awareness campaigns to raise their profile."

ZSL's EDGE of Existence programme invests in conservation at a grass-roots level. ZSL supports aspiring conservationists in developing countries to lead the research and conservation action of a local EDGE species – an effective and sustainable way to ensure the long-term survival of these animals. Fondation Segré generously supports ZSL's EDGE Fellowship programme.

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