Broken Plastic, Coyotes, and Pronghorn: The role of trail cameras in solar-wildlife research

If you were to ask me what my favorite part about being a field biologist for Wildlands Network’s wildlife and renewable energy project is, I would say it’s the near-constant stream of data we collect in the pursuit of making the unknown known. From collared pronghorn, we get hourly location data, but the thing I get most excited about is the trail camera photos we collect.

Month after month, it never gets dull visiting every camera and forever getting the feeling of Christmas morning as I check to see what old friend we’ve captured again, what new species we collected, and especially what candid behaviors we would otherwise be unprivileged to see – like coyotes taking things from our camera sites.

A coyote steals a marking stick used to give reference to animals within photos.

The element of surprise and intrigue makes it even more disappointing when one of our cameras is stolen or damaged. That’s why, back in April when I was out checking cameras, I was both surprised and disappointed to find one of our cameras in bits and pieces on the ground – apparently destroyed by whatever machines left the tracks our camera was now lying in.

The camera had originally been mounted on a dead tree placed near a fence line. Never in our wildest imaginations did we think, out here miles from a city or a paved road, it would be demolished by a tractor out clearing brush and trees underneath a power line. Yet, little remained except plastic chunks and unfulfilled expectations of photos and information we had lost.

Our Strategy

Biologists use trail cameras as a way to study wildlife without having to capture them or interfere with their normal lives – a method often referred to as noninvasive sampling. Researchers use noninvasive methods, cameras in particular, because they cause less stress to animals and are more cost-effective than capturing and collaring animals. Wildlands Network employs hundreds of cameras across a variety of projects in North America.

For our Wildlife Interactions with Renewable Energy Development (WIRED) project, we are studying the effect utility-scale solar energy (USSE) has on wildlife in and around solar developments. To study wildlife’s interaction with the land before, during, and after development, we’re employing a variety of invasive and noninvasive methods in tandem.

Specifically, we have deployed 100 cameras distributed across 50 study sites (one-kilometer-squared hexagons). Within every hexagon, we placed between one and four cameras. Each site is assigned a random number of cameras, and, through this method, we can evaluate the number of cameras needed to detect our target species.

The objective of these camera arrays is to detect wildlife, document their relative use of each study site, and observe any changes in their behavior over time. In particular, we are interested to see if such changes happen in proximity to or as a consequence of recently constructed USSE developments.

Designing and operating any study can be complicated and challenging. For cameras, we must consider which metrics and species to prioritize, the spatial distribution of the cameras on the landscape, the duration and seasons in which cameras should operate, and the optimal camera placement within a hexagon to maximize detection. Once those factors have been decided, we then must effectively execute the study design and maintain the cameras.

Even the process of placing a camera at a site is not always straightforward. We must consider what type of structure we will affix cameras to, the angle to minimize obstruction from nearby vegetation or direct sunlight, and how far away we want the camera to focus.

For our project, all cameras are mounted on natural vegetation or fence posts located less than five feet off the ground and pointed in a northerly direction (lest we get photos of the sun). The cameras are aimed at a point about 20 feet away (usually at a small wooden stake that coyotes like to remove) at a downward angle of about five to 15 degrees. These considerations help standardize the view that cameras have and maximize the chances of detecting pronghorn, deer, elk, and mammalian carnivores.

Our Progress

Within individual study hexagons, we strategically deployed the cameras to maximize our chances of detecting wildlife. We focused on placing cameras in high-traffic areas (corridors, funnels, trails) where we hope that pronghorn and other mammals, especially carnivores, will cross.

For example, one camera we had pointed at a fence line where we noticed pronghorn tracks when we were selecting the site, and we had hoped that these same animals or others would follow a similar path and be detected along the fence.

Even though we do our best to reduce camera downtime caused by animals, wind, or other reasons, it is always a battle. Little did we know, the camera we mounted facing the fence line would soon be destroyed.

Like our other cameras, we check this one every month to exchange SD cards and ensure they’re functioning properly. In practice, these visits are not always simple (much to my chagrin). Cows often disorient the cameras by using them as scratching posts, wind can blow vegetation that causes tens of thousands of false triggers, and, on occasion, the cameras can mysteriously malfunction and kill the batteries prematurely (which typically last for months or even years).

A piece of silicon board from a destroyed trail camera on our WIRED project in northern New Mexico.

Despite its optimum placement, when we checked the camera, it had been reduced to plastic bits. The photos on the SD card were lost. Unfortunately, that is information we will never recover, and those photos may have revealed a collared pronghorn, a species we had not detected before at this particular camera site, or some novel interaction that is rarely detected like the coyote and American badger partnership we captured last year (below).

Due to our frequent camera checks, in this instance, we only lost a couple of weeks’ worth of data. This kind of loss of data is always frustrating, but it is an unfortunate part of field data collection. As a result, we always go out prepared with a replacement camera in case we lose a camera or it malfunctions.

Since replacing the destroyed camera with a new one, it has detected >600 instances of different wildlife and livestock. Six of these photos were of pronghorn, one of which a male, which is an important observation as we are attempting to count the number of bucks in the population. Similar numbers of pronghorn have been seen within the same sampling area by other cameras.

A male pronghorn walks in front of our camera location in early May 2024.

Another camera, less than a half mile away, captured photos of 10 uncollared pronghorn in a group. Why do we see groups of animals at one camera but not at others? Many factors may contribute, including simple random chance (luck), the location of the camera relative to existing trails, and proximity to an important resource like water.

A group of 10 pronghorn strolls past one of our cameras in northern New Mexico.

Our Impact

With each new piece of data we collect and synthesize, we better understand how wildlife use this landscape. We will also be able to use it to compare research methods between camera trapping and other noninvasive and invasive methods. This will help us determine which is most effective and efficient (costs the least) given the type and precision of data that it provides.

By using diverse analytical approaches that quantify whether different species use or avoid locations, we are getting one step closer to our study’s goal of offering insights into ways wildlife respond to solar development as well as ways to minimize USSE development’s impact on wildlife.

Perhaps most importantly, we hope this research using noninvasive methods will provide a means for others to evaluate their landscapes or potential solar sites and determine which species live there, their response to solar development, and how they might offset any negative effects. Collectively, this approach can keep landscapes connected for the pronghorn, coyotes, badgers, and more that live in New Mexico and beyond.

For more details on this study, visit our project website here.

A coyote carrying a prairie dog it captured at one of our study sites in northern New Mexico.