It’s a little batty how little we know about the world’s bats.

Oh, sure, the bats in the U.S. and some other countries have been fairly well studied. That’s because they actually need to be the subject of a lot of research. Not only do the famously flying mammals also provide an estimated $3.7 billion worth of insect control for farms in the U.S. alone, many of them are also dying from the fungal infection known as white-nose syndrome. Millions of dollars have been earmarked for studying that problem and looking for solutions.

But how are the rest of the world’s bat species faring? Oddly enough, we don’t know all that much. According to numbers crunched by Jessica Welch, a Ph.D. candidate at the University of Tennessee, the conservation status of 28 percent of the world’s known bat species is not currently understood. Nearly 200 species are currently listed as “data deficient.” Another 166 have never been evaluated for their extinction risk.

Even worse, we also don’t know the population trends for nearly half of the world’s 1,296 bat species in order to understand if their numbers are climbing or shrinking. That, combined with the lack of other data on so many species, means that many bats could be at risk of extinction without anyone being the wiser.

Welch came to this realization when compiling data from the IUCN Red List of Threatened Species for another project. “I noticed that there is relatively little information on bat extinction risk, given that we know so little about bat population trends and sizes,” she says. “For example, there are over 10,000 recognized bird species, with just 812 having an unknown population trend. For bats, 635 species have an unknown population trend.”

Now, going out in the field to try to collect population trend data for 635 species is a slightly insurmountable task. Welsh and her co-author Jeremy Beaulieu wondered if they could figure out which of these species were at risk using other methods. They decided to look at the information that we already know in order to calculate which bat species might be threatened by extinction.

Luckily, previous research had helped to identify several risk factors for bat species—including geographic range, whether or not they live on islands, and how many litters they have per year. With that in hand, Welch and Beaulieu created a set of mathematical models and began to crunch the numbers.

The results? The researchers found that six data deficient bats have a high risk of extinction, while ten species were what they called “of high interest.” They also calculated that many of the bats currently on the IUCN Red List may have higher or lower extinction risks than their current assessments.

One of the species that came out as being the most at risk typifies their results, although it also wasn’t much of a surprise given how little we know about it. Eptesicus dimissus, a rare bat species from Thailand and Nepal, has only been observed by science one or two times since it was first documented in Royal Chitwan National Park. The IUCN assesses the species as “data deficient.” Welch and Beaulieu calculate that it is at high risk of extinction.

“How can we know so little about a mammal that occurs in a national park,” Welch asks. “The reason this bat is considered endangered according to our model is that its predicted range is only 13 square kilometers! The could be an underestimate since we know so little about the bat, but until more field data on its distribution can be collected, it is important that this bat be protected where it is known to occur.”

That’s actually the next phase of her research: looking at the published data for every bat species to help prioritize which ones need more scientific data and, as a result, identify which parts of the world researchers should focus their efforts. Once that’s done, maybe some of that missing bat information can finally start to be filled in.

Previously in Extinction Countdown: