Scientific Research

Tracking Endangered Jaguars across the Border: The work of Sergio Avila

Did you know that until hunters spotted two jaguars in 1996, these big cats were thought to be extinct in the United States? Jaguars roamed freely in the southwestern US until they vanished from the area due to habitat destruction, hunting, and other human activities. However, thanks to conservation efforts by Sergio Avila and others, jaguars have returned to the region and are now studied and protected.

"Jaguars don't recognize political boundaries," says wildlife biologist Sergio Avila (Figure 1), the Northern Mexico Conservation Program Manager for the nonprofit group Sky Island Alliance in Tucson, Arizona. Avila ought to know. For nearly 15 years, he has studied the wildlife of southern Arizona and northwest Mexico, including the elusive and endangered jaguar.

Figure 1: Wildlife Biologist Sergio Avila, a native of Mexico, works for Sky Island Alliance in Tucson, Arizona.

image ©Jessica Lamberton/Sky Island Alliance

But rather than seeing his work as straddling the border between two countries, Avila sees it as connecting a single bioregion. "In ecological terms, it's the same place. It really doesn't matter if it's Mexico or the United States. The trees are the same, the rain is the same, the deer are the same," he explains.

Making connections that defy traditional boundaries, in the natural world and among people, has been a constant theme in Avila's career. While tracking a stealthy cat through the wilderness may seem like solitary work, Avila has learned that drawing in all kinds of people and forming partnerships is key to successful research and conservation.

Where the jaguars roam

Sleek, muscular, and weighing in between 40 and 135 kilograms, jaguars are powerful, majestic cats (Figure 2). Known to scientists as Panthera onca, they are the largest feline species native to the western hemisphere, and the only one capable of truly roaring like a lion or tiger.

Figure 2: A passing jaguar (Panthera onca) triggers a camera "trap" used to study wildlife in Northern Mexico. These large, elusive cats have a characteristic pattern of black spots and rings known as rosettes.

image ©Sky Island Alliance/El Aribabi

Today, it may be difficult for you to imagine these big cats roaming the southwestern US. Their golden-colored coats dappled with black rings and spots may seem like they belong in the tropical jungles of South America. But in the mid-1800s, the jaguar's range extended from Argentina and Southern Brazil all the way to present day Arizona, New Mexico, and Texas. Historical records of kills by hunters and wildlife managers from the first half of the 20th century show that jaguars even wandered as far north as the Grand Canyon.

Over the decades though, their numbers dwindled, mostly due to destruction of habitat, hunting, poaching, and removal by government officials and ranchers trying to protect cattle operations. The northern jaguars (those in the southern US and northern Mexico) were hit hard by these human activities, and sightings became less and less common. By 1990, the Arizona Game and Fish Department considered jaguars to be completely extinct in the US.

Then in 1996, something happened that would radically change both the status of jaguars in the US and the course of Sergio Avila's career.

Two hunters, Jack Childs and Warner Glenn, photographed two different male jaguars in southeastern Arizona and southwestern New Mexico. The sightings, nearly six months apart and in two separate mountain ranges, proved that jaguars still roamed – at least occasionally – in the US. While most scientists believe that both cats crossed the border from a breeding population about 225 kilometers south in Sonora, Mexico, the photographs stirred new interest in studying and protecting jaguars within the US. The following year, the US Fish and Wildlife Service added jaguars to the Endangered Species List. (They are also protected by similar legislation in Mexico.)

That same year, Sergio Avila graduated from the University of Aguascalientes in Mexico with an undergraduate degree in biology. He had not heard about the hunters' sightings north of the border and had no idea that they would eventually have a major impact on his life and career.

Comprehension Checkpoint
Jaguars were added to the Endangered Species List after two were __________ by hunters in the US in 1996.

Finding his niche

Avila had always been fascinated by wildlife, especially apex predators. As a child, he dreamed that he had a pet African lion in his backyard and would pore over encyclopedia articles about animals.

"My parents are both physicians, and I grew up surrounded by science books and scientific language," he says. "In those early years, I started learning English, too. Even though my parents weren't fluent in English, they could read in English and write in English. So it was a good way to understand why learning another language was going to help in the future."

Growing up and going to college in central Mexico, Avila often found that his perspective and interests differed from those around him. "I was not typical in so many ways – traditionally, culturally, the way I was raised, and other things – so I didn't feel I was fitting in really well down in Mexico," he recalls. Among other things, most people he met did not see wildlife conservation as essential or urgent. To them, conservation was perhaps a nice leisure activity. But for Avila it was a passion that would become his life's work. (For more about how science benefits from the creativity, curiosity, and personal experience of scientists, see our module about Scientists and the Scientific Community.)

After earning a bachelor's degree in biology and trying a couple of different jobs, Avila went to graduate school to study Arid Lands Management in northern Mexico. He continued to focus on wildlife, and for his master's thesis he was involved in a study investigating why mountain lions were killing cattle in Baja California. But Avila was more interested in the opposite question: What were the mountain lions losing because of cattle? How was grazing affecting their habitat and prey?

"I don't pretend to think like a cat, but I try to look at it from their perspective," he explains. "What are they gaining or losing because of what we are doing? How does this benefit them or harm them?" This approach ultimately led Avila to his first job tracking big cats. In 2003, his advisor from graduate school hired him to conduct research on mountain lions and jaguars for what would eventually become the Northern Jaguar Project.

For four months, Avila worked in an isolated mountain range in Sonora gathering data on where the cats lived, how far they roamed, and what they ate. He spent his days hiking and looking for evidence of the cats, such as tracks in the soil, remains of prey, hair, or droppings (called "scat"). He combined these low-tech observation techniques with two pieces of technology that would be important to his work later on: radio tracking collars and camera traps.

Figure 3: A jaguar, nicknamed Macho B by researchers, wearing a radio telemetry collar.

image ©Arizona Game and Fish Department

Telemetry tracking devices, which use radio transmitters, are beneficial in wildlife studies that require detailed information about where an animal spends its time (Figure 3). But putting a radio collar on a jaguar can be difficult and dangerous – for the researcher and the cat. On the other hand, small, self-contained camera "traps" (Figure 4), which take pictures when triggered by a passing animal, offer snapshots of the animal's behavior and movements. This technique is less disruptive for the animal and may capture other clues about its health and behavior, but piecing the pictures together into a larger pattern can be challenging.

Figure 4: Researchers like Sergio Avila use motion-sensitive camera "traps" as a less invasive way to study jaguars and other wildlife.

image ©Sergio Avila/Sky Island Alliance

After that research concluded, the University of Arizona hired Avila for a summer position studying pygmy owls in Sonora. The project needed a biologist who spoke Spanish, knew the region, and was familiar with telemetry techniques. While the research itself was in Mexico, Avila was based in Tucson, Arizona. That was his first taste of living in the US. At first he wasn't sure he would stay. "When I came here, I didn't know if I liked it," he says. "I remember telling people, 'I'll be here for three years. I'm going to work and make some money, and then I'll go back.'"

But the following winter, Avila took a job with Sky Island Alliance, a nonprofit group that works to protect and restore the species and habitats of the southwest sky island region. Much of Avila's work focuses on the Madrean Archipelago, a collection of forested mountaintop "islands" separated by large "seas" of a different biome (such as desert or grassland). The archipelago extends into the states of Arizona, New Mexico, Sonora, and Chihuahua. It is an area rich in biodiversity and home to some rare species, including jaguars (Figure 5).

Avila quickly realized that he was home. "Coming here, it took very little time to realize that I wasn't crazy – that there were a lot of conservation-minded people like me. I just didn't know they existed," he says. "That was cool! That was like finding my niche."

Figure 5: The Sky Island region of the southwestern US and northern Mexico (outlined in red) crosses into two countries and four states. Because of its location, biodiversity is extremely high with species mixing from the Sonoran and Chihuahuan Deserts, the Rocky and Sierra Madre Mountains, the Great Plains, and the Neotropics.

image ©Sky Island Alliance
Comprehension Checkpoint
Which tracking technique is less disruptive to animals?

A wildlife biologist at work

In addition to finding people who share his passion for wildlife and wild places, Avila enjoys the constant variety of his job. He still spends time in the field studying jaguars and other wildlife, but every day is different. His projects keep him in touch with a wide variety of people: scientists in academia, government agencies, the media, volunteers, and the general public. And with only about a dozen people on staff, everyone pitches in, taking turns stopping by the post office or taking the research truck to the mechanic.

Being bilingual has continued to be helpful in Avila's work. While several people on the Sky Island Alliance staff speak Spanish, he is the only native speaker. When he started in 2005, the organization was only working north of the border. Avila extended the work to Mexico, using his language skills to form new partnerships.

Ranchers and other private landowners are one group that Avila has worked hard to build relationships with. In the US, he often conducts research on public lands managed by federal agencies like the Forest Service. But in Mexico, much of the prime habitat for big cats and other wildlife is on private land.

Currently, Avila works with about a dozen landowners who allow him to set camera traps and bring teams of volunteer researchers onto their land. The trust needed to form these partnerships must be built over time, and he says there is "no recipe" that works for everyone. "Little by little, I've been learning that not everybody trusts people in the same way. Not everybody sees biological research the same way," he explains.

Maintaining good relationships means going back to the landowners and sharing the research results. "We need to make sure that people understand that their little piece of land is part of a larger landscape – that their home or ranch is important because of the water quality, or the forest they have, or the species that live there," Avila says.

Helping a cryptic cat

Back in 1996, when two jaguars were photographed in the US for the first time in a decade, scientists and wildlife managers had a lot of questions to answer. Where did the cats come from? How many are there? How far did they travel? What paths, or corridors, did they use to get here? Are they staying or just passing through?

Helping a species in trouble is rarely simple, but jaguars are a particularly tough case. Like other large, elusive carnivores, it is difficult to observe them in their natural habitat. And compared to many other animals, scientists know little about their food and habitat needs, especially in the northern part of their range near the border.

But researchers have been creative in piecing together evidence from many sources. In 2000, wildlife biologists David E. Brown and Carlos López-González (Avila's advisor from graduate school) published a paper mapping jaguar sightings in Arizona and New Mexico between 1900 and 1999 (Brown & López-González, 2000). By pulling together hunters' photographs, historical newspaper articles, records from wildlife agencies, specimens in museum collections, and other published accounts, the researchers created a snapshot (Figure 6) of where – and when – the cats had been spotted in the US. (For more about how visualizations, such as maps, can highlight patterns in a dataset, see our module Data: Using Graphs and Visual Data.)

Figure 6: Carlos López-González (Avila's advisor from graduate school) and David E. Brown pieced together hunters' photographs, historical newspaper articles, records from wildlife agencies, specimens in museum collections, and other published accounts to map a century of jaguar sightings in the southwestern US.

Reprinted with permission from: Brown, D. & López-González C. (2000). Notes on the Occurrences of Jaguars in Arizona and New Mexico. The Southwestern Naturalist, 45, 537-542.

image ©The Southwestern Naturalist

Brown and López-González's analysis included 62 reported sightings. A later study by Arizona Game and Fish officials (Hatten, Averill-Murray & Van Pelt, 2005) offered a model of potential jaguar habitat building on an even smaller dataset of 25 sightings that they deemed most reliable (those that were corroborated or reported by an expert and that had specific information about location). For conservation purposes, scientists and wildlife managers need to extrapolate a bigger picture of potential jaguar habitat from a collection of isolated sightings, but interpreting the very limited data in a meaningful way is challenging. (For more about how scientists move from raw data to evidence that supports a scientific hypothesis, see our module Data: Analysis and Interpretation.)

To help fill in the gaps, Hatten et al. and many other researchers have used geographic information systems (GIS) to combine sighting data with other types of information, such as vegetation cover, altitude, and locations of water sources. This allows them to create computer models that predict which areas are likely to be good jaguar habitats and which corridors the cats are likely to use when traveling from one area to another.

Scientists can refine these predictions based on what they know about other large cat species and observations in tropical areas where jaguars are more common. For example, researchers know that adult male jaguars can travel long distances (as far as 800 kilometers) while searching for territory not occupied by other males. Females and their cubs are more closely tied to specific food and shelter needs, so they tend to have a smaller home range. Thus, a sighting of a male jaguar has different implications for a habitat model than a sighting of a female does. López-González and a collaborator from the US Geological Survey, Erin Boydston, combined that knowledge with sighting records to map the potential distribution of jaguars in the border region (Boydston & López-González, 2005).

By overlaying roads and other human activities that threaten the cats, scientists have also used GIS to suggest high priority areas for conservation efforts. In one example, the International Union for the Conservation of Nature's Bordercats Working Group convened a workshop for land managers, conservationists, and scientists to share their collective knowledge about jaguars and two other cat species in the border region. In 2009, they published a paper (Grigione et al.) that offered a blueprint of priority conservation areas – places where the cats were known or predicted to occur that were also threatened by human activities (Figure 7).

Figure 7: A map of Cat Conservation Units (CCUs) and Cat Conservation Corridors (CCCs) generated during a Bordercats Working Group workshop. Areas of highest conservation priority were determined based on the presence of jaguars and human activities that threaten the cats.

Reprinted with permission from: Grigione, M., Menke, K., López-González, C., List, R., Banda, A., Carrera, J., et al. (2009). Identifying potential conservation areas for felids in the USA and Mexico: integrating reliable knowledge across an international border. Oryx, 43, 78?86.

image ©Cambridge University Press
Comprehension Checkpoint
To build computer models that predict likely jaguar habitats, researchers relied on

The truth on the ground

GIS models can be incredibly helpful in conservation biology, especially when data are limited. But like all tools of science, they must be tested and calibrated. When he began working at Sky Island Alliance, Sergio Avila decided to test some of the predictions made by the GIS habitat models for jaguars and other big cats. Armed with camera traps and a keen tracker's sense, he began ground truthing. "I used their maps and models to go to places where they predicted we would find jaguars or ocelots, and I studied those places," he explains.

In seven years, Avila estimates that he has set between 30 and 40 camera traps, which have captured nearly a dozen photos of jaguars, plus thousands of photos of other wildlife. Each photo is a data point helping to map where jaguars and other wildlife are found.

Gathering that data is a slow process. On a typical field trip, Avila and a group of volunteers will hike the creeks and contours of a property for three or four days and check a dozen remote cameras. They make sure each camera is in working order, replace memory cards and batteries, and continue on hoping that the pictures they have collected will reveal something interesting.

Working with volunteers and students, or citizen scientists, is an important part of the research. Avila trains them to identify tracks and other signs of wildlife like scat and "kill sites" with leftover prey. The training is serious, usually lasting about five days, and volunteers are carefully instructed in a protocol to follow for collecting the observational data. This helps ensure that the information that volunteers collect is reliable.

"You don't just find things or see things and say that's it," says Avila. "You have to have some training to know what you are seeing. You have to have evidence, likely a photograph or a track, that other people can verify." (To read more about the difference between casual observation and scientific data collection, see our module Research Methods: Description.)

Putting the data to work

When he returns from the field, Avila begins analyzing the data he has gathered. He records any details he can mine from each of the camera trap photos and videos. Which species were photographed? How many? Is an individual male or female? Does it appear to be a previously photographed individual? Does it appear healthy? If the cameras caught a jaguar on film, Avila informs the Jaguar Recovery Team.

The Recovery Team is a bi-national group of experts and stakeholders assembled to help the US Fish and Wildlife Service put together a recovery plan for northern jaguars. Among other things, the agency will use the information and recommendations that the Team assembles to help designate and protect the species' critical habitat in the US. Given that knowledge of jaguars north of the border is still limited, making that designation will not be easy or quick. "They need more information about where the jaguars are in order to define their habitat," Avila says.

To help gather that information, the Fish and Wildlife Service has granted the University of Arizona's Wild Cat Conservation and Research Center funding to study where the cats are found in the Southwestern US, how many there are, and how they are connected to populations in Mexico. (To read more about how scientific research is funded, see our module on Scientific Institutions and Societies.)

In the meantime, Avila and his colleagues at Sky Island Alliance are working to make all their wildlife data available for research, education, and conservation. Photographs and other evidence of sightings from their work, the scientific literature, and public and private collections are being compiled in an online database called the Madrean Archipelago Biodiversity Assessment (MABA) Project.

In Mexico, state agencies have used the data to help understand where certain plant and animal species are found and the impacts humans have had on riparian areas. Students have also begun accessing the data, and Avila plans to offer training to help them navigate and use the MABA database effectively.

Of all of his work, Avila is probably proudest of his role in an event that occurred in the spring of 2011. Working with the landowner, Avila had documented jaguars and ocelots on a large ranch about 50 kilometers south of the border. The landowner, Carlos Robles, took these findings to the Comisión Nacional de Áreas Naturales Protegidas (similar to the US National Park Service). Proof of the large cats' presence – combined with research from other groups showing a variety of migratory birds, endangered species of plants and animals, and permanent flowing water – led to the creation of the Rancho El Aribabi Natural Protected Area.

Under this designation, the Robles family retains ownership of the ranch and commits to managing the land in ways that maintain its healthy condition and rich biodiversity. The preserve now attracts visitors from both sides of the border for eco-tours and activities like hiking, camping, and bird watching. Volunteers are helping restore areas damaged by cattle grazing, and the ranch has hosted scores of students and other community members from Mexico, Spain, France, and the US for educational events and workshops.

At its core, the preserve protects 10,000 acres of land and the wildlife that lives there, but Avila believes its legacy will be much larger than that. In his vision, Rancho El Aribabi is a model for community-based conservation and the first in a network of conservation ranches in northern Mexico that will act as stepping stones for jaguars and other wildlife to move across the land. "It's really cool and extremely important. I think it's the biggest thing that I have been part of in my career," he says.

Christine Hoekenga “Tracking Endangered Jaguars across the Border” Visionlearning Vol. SCIRE-1 (7), 2012.


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  • Avila, Sergio, e-mail messages to author, February 24, 2012 and April 6, 2012.
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  • Boydston, E. & López-González, C. (2005). Sexual differentiation in the distribution potential of the northern Jaguars (Panthera onca). USDA Forest Service Proceedings RMRS-P-36, 51-56.
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  • Grigione, M.M., Menke, K., López-González, C., List, R., Banda, A., Carrera, J., et al. (2009). Identifying potential conservation areas for felids in the USA and Mexico: Integrating reliable knowledge across an international border. Oryx, 43, 78-86.
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  • U.S. Fish and Wildlife Service Arizona Ecological Services Field Office. (2012, April.) Recovery outline for the jaguar (Panthera onca). Retrieved May 20, 2012 from
  • U.S. Fish and Wildlife Service Arizona Ecological Services Field Office. (2011, January.) Jaguar critical habitat determination to be informed by scientific models. Retrieved February 28, 2012 from
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