National Geographic

The Females of the Madagascar Sucker-Footed Bat are Missing

For the last six years, Paul Racey has been trying to find a female eastern sucker-footed bat. He has failed. The bats only live in Madagascar and since 2007, Racey’s team have tramped through the country’s eastern forests with nets, bags, and devices that detect the bats’ sonar. They’ve captured 298 individuals, some many times over. But every single one of them was male.

Where are the females? Why are they so ridiculously hard to find? And why do they segregate themselves from the males? No one knows. After so much fruitless searching, Racey doesn’t even have a good hypothesis.

All he knows is that the females must exist. For a start, a Smithsonian team once collected a female sucker-footed bat around 30 years ago, and it’s still housed in their collection. Also, Racey keeps on finding young males every year. “You can hold their wings up to the light and see bits of cartilage round their joints, which haven’t ossified fully,” he says. So, the bats must be reproducing. “There have to be females. It’s just that we can’t find them, and it’s very embarrassing.”

To put this in perspective, Racey has spent his entire career studying bats and has worked in Madagascar for 20 years. He’s vice-president of the UK-based Bat Conservation Trust, and has received a lifetime achievement award from them. He has published more than 200 papers on bats and edited textbooks about them. He even has a bat species–Racey’s pipistrelle–named after him. This is not a man who is accustomed to being unable to find a bat.

“I set out to do a study on the ecology and social organisation of [the eastern sucker-footed] bat and I’ve only done half of it,” he says. “I’m not used to that sort of failure.”

Eastern Madagascar sucker-footed bat. Credit: Paul Racey

Eastern Madagascar sucker-footed bat. Credit: Paul Racey

The sucker-footed bat (Myzopoda aurita) lives only in Madagascar and was discovered in 1878. For the longest time, people thought that it was the only representative of its family, with no close relatives anywhere in the world. Then, in 2007, Steve Goodman found another one next door. This western sucker-footed bat (Myzopoda schliemanni) lives in the island’s dry western forests while its previously known cousin inhabits the humid eastern forests. The western one poses no mystery—both sexes huddle together in the leaves of the Bismarckia palm. It’s the eastern males that lead an unprecedentedly monastic lifestyle.

Why should the females live apart from the males? “I have no credible hypothesis,” says Racey. The closest example is another bat called Daubenton’s bat. In some northern English valleys, males are found at higher altitudes and females are found lower down, although the gulf between them isn’t absolute. It also exists only in the breeding season, possibly because pregnant females struggle to cope with the harsher high-altitude environment. But this explanation can’t possibly apply to the sucker-footed bats, which live in a low valley.

The males, at least, aren’t hard to find. They roost in the Ravenala tree, or “traveller’s palm”, whose giant leaves spread out like a fan. The start as rolled-up tubes and gradually unfurl over several days, creating a hollow cavity that’s perfect for the bats. Racey once found 53 of them in a single leaf.

Over six years, he and his research assistant Mahefatiana Ralisata have tried to capture these bats by suspending huge nets between trees, and by sending climbers to the top of Ravenala plants with large cloth bags.

They mostly operated out of a coffee research station in south-eastern Madagascar, but they also carried out exhaustive searches of two neighbouring valleys. Young bats can’t fly very far since their arm bones haven’t fully hardened, so if they’re found at a specific site, their mothers are unlikely to be far away. But—aaargh!—where are they? Racey and Ralisata made 833 captures in total. They’d find the same bats again and again, but never any females. They even went back to the village where the Smithsonian found their female. Nada.

It hasn’t been a total loss. The team has learned more about the natural history of the bats. For example, they seem to be completely free of external parasites like ticks or fleas. “That’s easy to explain,” says Racey. “The roosts are spotless.” By huddling inside a rolled-up leaf, the bats protect themselves from parasites. They also stick exclusively to Ravenala. Banana leaves, while also shiny, green and coiled, never contain any bats. “I’m guessing that bananas grow too low and get hammered by rats,” says Racey. “If a rat found a bat, it’d eat it.”

The team have also shown that the bats are poorly named. They stick to leaves with tiny discs on their wrists and ankles, which were thought to act like suckers. But true suckers are held to surfaces because the air pressure outside them is greater than the pressure within their rims. That’s not how the bat’s discs work. Instead, Racey found that they secrete a sweat-like liquid that holds them against a leaf “like a licked piece of paper stuck to a window”. So, the sucker-footed bat isn’t sucker-footed. (The traveller’s palm isn’t a palm, either. Oh, you wacky biologists.)

Meanwhile, the whereabouts of the females are still a mystery. Racey suspects that they live in two very different populations—perhaps one in the high mountains and another near the coast. This would explain why the juveniles arrive in two waves every year, even though every other bat of the same size only has one annual breeding season.

We’re unlikely to find these female enclaves until our technology improves. “If I had a wish, it would be for a satellite tag that’s small enough to go on a 10 gram bat,” he says. Then, the task would be easy. You could just open a laptop and follow the males to wherever their mates are.

Suitably small trackers are probably years off and when they do arrive, someone else will have to use them. Racey is done. He’s had two grants from the National Geographic Society to fund his search, and is not planning on applying for more. “I’m 69,” he says. “We’ve done what we can, but we’ve been pissing in the wind.”

His one consolation is that he has left behind a legacy of scientists in his wake. During his stay in Madagascar, he helped to set up a non-governmental organisation called Madagasikara Voakajy,  dedicated to protecting the country’s wildlife, and training local biologists to do their own unassisted research. “It’s working,” he says. The organisation now has a female Malagasy director and Ralisata (Racey’s assistant) got her PhD on the back of the sucker-footed quest.

There are 17 Comments. Add Yours.

  1. Brian Del Vecchio (@Hybernaut)
    May 31, 2013

    Fascinating read. Thanks, Ed. As an engineer it’s hard for me to read this and not think of Mr. Racey’s 20 year search as a failure, but I’m sure he and his team have contributed a great deal to our understanding of bats.

  2. Danny
    May 31, 2013

    I’m a sucker for all footed bats

  3. Simon Balfre
    May 31, 2013

    Could the females be disguised as males?

  4. Stephen Lys
    May 31, 2013

    I’ve seen scientists tag monarch butterflies and track their migrations. You should be able to tag a bat… http://glimpsesoflawrence.blogspot.ca/2009/05/radio-tagging-monarch-butterflies.html

  5. Thomas Kelly
    May 31, 2013

    Kinda weird…But has this ever happened before? And could the females live elsewhere? After all, we barely know anything about these females…

  6. Dale
    May 31, 2013

    I was sure they’d gotten tracking tags down to half a gram.

    They have, but they’re light-level based, and so nowhere near as accurate as GPS. The lightest GPS ones are 2 grams.

    Soon!

  7. Aggie
    May 31, 2013

    what if one of them – females or males are hybrids with other species? like it happened with frogs some frogs?

  8. Steve Morrison
    May 31, 2013

    They’ve probably gone off to wherever the Entwives are.

  9. RISHI DWIVEDI
    June 1, 2013

    may be the females do not come out of their hiding/nesting places at all… and probably the males take care of their daily needs.

  10. Wael M. Shohdi
    June 1, 2013

    Very interesting article! I really appreciate this immense effort and hope in the near future this mystery will be solved after all. Well done!

  11. chris y
    June 1, 2013

    Why should the females live apart from the males?

    Because the males insist on leaving their toenail clippings in the bath?

  12. Kathy K.
    June 1, 2013

    “Racey suspects that they live in two very different populations—perhaps one in the high mountains and another near the coast.”

    So maybe the males have two families (unaware of each other)?
    :)

  13. Jan Vones
    June 1, 2013

    They probably nest on etnwives.

    http://en.wikipedia.org/wiki/Ent#Entwives

  14. Trish Wimberley
    June 3, 2013

    Paul I think if you ask Steve Goodman you will find that it was me that captured those Myzpoda when we were over there with Merlin Steve is a great guy knows so much we were all out that night we had one net left over and Terry suggested we set it up across this little road everyone thought no way anyway Terry yells to come quick and all these bats started hitting the net at once they were chasing a whole heap of moths i just kept grabbing them out of the net didnt look to see what they were it was neat everyone was excited as it had been years since they had seen them and thought they had gone extinct.

  15. Jim Ryan
    June 3, 2013

    I worked in Madagascar with Ken Creighton in 1988 and 1989. We caught 2 female Myzopoda (and several males) in the region near Mount Vatovavy. Not far from the town of Kianjavato east of Ranomafana National Park. The specimens are at the Smithsonian Institution.

  16. BKNautiyal
    August 14, 2013

    I feel the search is only halfway.Once the Genome mapping is done things will clearup.Keep going pl.

  17. Stephanie Rose
    August 18, 2013

    Hybrid? My clown fish all started out as males. Who ever is more dominate turns into the female. If I remove my female and add a less dominate male, my old male will become a female? I wonder if I remove my male if I put in a more dominate male, if that new male will turn to the female while the old female turns back? Interesting… experiment in the works. Has the reproductive system of these bats been completely investigated?

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