More than 14,000 species are listed as endangered or critically endangered by the International Union for Conservation of Nature. Some scientists have called for naming the present geologic epoch the Anthropocene, or “human era,” after the main source of startlingly rapid rates of species extinction and other environmental perturbations.

Understanding the biology of the species that are most at risk from this disturbance is a critical prerequisite to developing effective strategies to conserve them. But scientists who survey endangered animals have to grapple with a number of special challenges alongside the traditional research pressures of publishing and grant writing.


For a start, there are the problems of finding organisms that are, by definition, relatively rare and may also tend to be elusive, nocturnal, or otherwise difficult to observe. Then, there’s the risk of researchers exacerbating the very issues contributing to a species’ or population’s demise—for example, by increasing human contact or inadvertently raising the species’ visibility to poachers.

In the face of these issues, scientists are coming up with unique and creative solutions, from making use of new technologies to advising researchers on how best to present their results.

Where are you?  

The tiger quoll (Dasyurus maculatus) is a housecat-size marsupial endemic to Australia. While numbers of the species have been increasing following drastic declines shortly after European colonization, several populations are still considered endangered. Tiger quolls are elusive creatures and provide a challenge to researchers such as Emma Bennett, a wildlife ecologist at Monash University in Melbourne who studies their ecology.

One option to facilitate the search is to use traps. But traps may injure or at the very least stress the animals—an outcome that researchers are obviously keen to avoid. Bennett, instead, is working to develop a far less invasive solution: dogs trained to track down the tiger quolls’ scat, which can be analyzed to determine sex, diet, and information about the quolls’ distribution. She recently partnered with a search-and-rescue dog trainer to teach volunteer conservation dogs how to locate quoll scat in Great Otway National Park in Victoria. “The dog handlers . . . are just passionate people who are interested in helping the environment,” she says.

Now, you put camera traps out in remote places and that’s how you see all this imagery of snow leopards and tigers and all sorts of wonderful animals that you would never see any other way.

Stuart Pimm, Duke University

Bennett’s strategy is just one example of how researchers studying endangered species are coming up with unorthodox solutions to the logistical challenges of tracking or observing organisms that are few and far between. Paul Evangelista, a research ecologist at Colorado State University, came up with his own approach while working in Somaliland, a small breakaway region of Somalia and self-declared state in the Horn of Africa. Somaliland has remote, hazardous regions where directly observing animal populations is very difficult. So Evangelista turned to locals. “I hold a lot of value towards indigenous knowledge, and I was trying to figure out how I could use some of that information to integrate into some of these more computer-based geospatial models,” he says.

Evangelista’s team surveyed citizens of Somaliland in 2016 and 2017, asking them whether any of 25 species occurred in their local areas. The researchers included a few species in the survey that they already knew were locally extinct as a quality control against false reporting. With the data they collected, the scientists were able to build species distribution models of the animals, including two of high conservation priority, the cheetah (Acinonyx jubatus) and the African wild ass (Equus africanus).

New technology is playing an increasing role, too, says Duke University conservation ecologist Stuart Pimm. Camera traps, for example, are progressing by leaps and bounds as digital cameras replace film ones. “Now, you put camera traps out in remote places and that’s how you see all this imagery of snow leopards and tigers and all sorts of wonderful animals that you would never see any other way,” says Pimm. This is filling in gaps in our knowledge of the distribution of these elusive species, he says.

Drones are increasingly being recruited to identify and locate hard-to-find animals as well (see “Fly-by” below). “Now you can go out and buy a helicopter kit, put a camera on it . . . and [get] very high-resolution images,” Pimm says. In 2016, for example, scientists at Woods Hole Oceanographic Institution and the National Oceanic and Atmospheric Administration (NOAA) used drones to study the health of critically endangered North Atlantic right whales (Eubalaena glacialis).

Pimm says that technologies that were either nonexistent or nascent a decade ago have “become quite standard procedures for studying biodiversity and what we humans are doing to it.” He notes that technology may be fundamentally changing the nature of biodiversity and conservation research. “We’re increasing by many orders of magnitude the rate at which we accumulate data,” he says.

We just have to be very conscious of who sees that data and who has access to it.

—Paul Evangelista, Colorado State University

But even when researchers manage to collect data on their species of interest, challenges remain. The next immediate hurdle involves how to communicate research on endangered species to the larger scientific community—or whether to communicate it at all.

Death by print

When conservation and landscape ecologists David Lindenmayer and Ben Scheele of the Australian National University published location information on pink-tailed worm-lizards (Aprasia parapulchella), a species the International Union for Conservation of Nature lists as “vulnerable,” their institution soon began getting calls from landowners reporting people trespassing on their property to find the animals. Some of the trespassers, who overturned rocks looking for the reptiles, may have been involved in illegal pet trafficking.

That episode joined a long list of examples of research-savvy poachers targeting rare animals almost as soon as they were described in the literature. Even well-meaning amateur naturalists can unwittingly upset endangered species just by trying to catch a glimpse. “It’s quite a specific microhabitat that some of these animals rely on,” says Scheele, “and even just searching for animals can be really damaging.”

The resulting quandary of whether or not to publish data on endangered species’ locations pits science’s fundamental need for transparency against the risk of sensitive information falling into the wrong hands. Evangelista says he and his colleagues have sometimes kept sightings of rare organisms “under wraps” because of their concerns about blowing a species’ cover. Indeed, when the researchers published their findings from Somaliland this March, they decided not to report details about the distributions of most of the species they studied. “As researchers that are on the ground, it really puts us in a very tough situation,” he says. “We’re not just doing this to publish papers—we’re out here trying to save species, and we just have to be very conscious of who sees that data and who has access to it.”

Lindenmayer and Scheele addressed the issue head-on in a paper published last year entitled, simply, “Do Not Publish” (Science, 356:800–801). In the paper, the researchers laid out the case for protecting data on critically endangered species, and they proposed an assessment that scientists could use to decide whether they should publish their information in the literature. The assessment includes criteria on a species’ status and its risk from poaching. The provocatively titled paper “triggered a debate on how to deal with the data,” says Scheele, although he notes that the assessment doesn’t apply to most species, as there aren’t many that are critically endangered, threatened by poaching, and highly localized. “Only a few species really need the assessment,” he says.

The argument grabbed the attention of a number of other conservation biologists. Glenda Wardle, an ecologist at the University of Sydney, was a coauthor on a response that argued for open but responsible publishing. Biodiversity research “requires location information in order [to make] an assessment of the risks and threats,” she says. “So if we don’t publish—in other words, if we don’t allow scientists and managers to know the full extent of the information—we’re holding back the actual biodiversity progress that we want to achieve.” Wardle argues that conservation biologists have always had good practices for sensitive data, but she adds that the 2017 article, and the response she coauthored, probably helped put the issue back on the conservation biology community’s radar.

To help researchers decide how to communicate their research on endangered species, University of Sydney ecologist Ayesha Tulloch and her colleagues recently designed a decision tree for publishing sensitive location data that will allow scientists to weigh the risks due to poaching and amateur visitors against the potential benefits of enhanced conservation work. “Even if you’re not in the conservation sphere, you should still be very aware of the conservation implications of your work and the threats to your species,” says Tulloch. She says that getting relevant data to non-governmental organizations (NGOs) so they can act on them is a perennial problem in conservation ecology. NGOs can only make good decisions around wildlife management and habitat conservation “if they have the most up-to-date, the most high-quality information on where the species are and what’s threatening them.”

Making Connections

Getting other parties—such as conservation organizations, local and national governments, and the public at large—involved in studying and protecting endangered species is an ongoing challenge for biodiversity researchers and ecologists. Just acquiring permits from government agencies for observational studies can take years, says Kristin Aquilino, a biologist at the University of California, Davis, Bodega Marine Laboratory. While scientists wait for paperwork to clear, species can become locally extirpated—or worse, go extinct altogether. “It can be hard to act quickly when you have to go through that permitting process,” she says. Meanwhile, scant resources make pursuing long-term studies difficult.

For researchers themselves, burnout can set in. Scheele says researchers working with critically endangered species “sometimes have to take a step back.” Some of his colleagues have left ecology altogether because seeing habitat destruction occurring before their eyes weighed on them. There may have been several study sites when the research started, but “now they’re under a house or a road,” he says.

One way researchers are working to improve this situation is by trying to increase public engagement in gathering data on endangered species. Although it is often difficult to get the public to understand the value of animals other than so-called charismatic megafauna—large, beautiful animals such as whales and pandas—a number of initiatives are enlisting technology to get people personally involved in endangered-species assessments.

An increasingly popular app called iNaturalist, for example, encourages researchers and amateur naturalists to upload up to 1 million images a month to a database that maps observations from around the globe. Pimm calls the iPhone “almost the perfect tool” for citizen scientists to explore biodiversity. “I can take my phone and wander out into the woods and take a photograph of a plant or frog or insect . . . and post that observation on the web. Even if I don’t know what it is, there will be a crowd of experts out there that will identify it for me.”

Aquilino, meanwhile, stresses the importance of collaboration to mitigate the most difficult aspects of working with endangered species. Her lab teams up with agencies such as the California Wildlife Foundation and NOAA to study the effects of ocean acidification due to climate change on white abalone (Haliotis sorenseni). “What’s so great about having so many partners [is] everyone brings something different to the table,” she says.


As unmanned aerial vehicles—commonly called drones—become cheaper, easier to use, and more widely available, conservation biologists are using them more and more to study endangered animals in the field.

Drones have the advantage of being able to fly over terrain that is inaccessible to ground-based researchers, and they may be able to get closer to animals than field workers can without disturbing them. Quadcopters and other hobbyist drones can be equipped with both optical and thermal imaging systems that enable the devices to locate animals that may be otherwise concealed, making survey counts more precise and accurate. Researchers can then analyze those images using computer algorithms, rather than by hand, vastly speeding up data processing and analysis. Some teams are even now turning to drones to track down poachers without putting park rangers’ or researchers’ lives at risk and to find sick or injured animals.

But there are also potential adverse effects on wildlife. Flown too close, the devices can disrupt behavior. And a 2015 study reported that American black bears (Ursus americanus) exhibit a physiological stress response to the aerial vehicles’ presence even when they show no behavioral change, suggesting that drones may be more intrusive than previously thought (Curr Biol, 25:2278–83).


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