Using Camera Traps to Study Wildlife

Bushnell Camera trap. Shot by Ishan Shanavas.

Studying the behaviour of wildlife is hard. Animals tend to shy away from humans, and thus observing their behaviour in the wild is hard. One must rely on observations from watchtowers, blinds, and transects, which are cumbersome and prove inefficient. It requires extreme patience, not to mention remaining quiet for hours. Moreover, many species live a nocturnal life, and thus studying them becomes all the more arduous. 

To tackle this, scientists have devised many methods. One of them is by placing motion-sensitive cameras (called camera traps) in the forest. When it detects an animal in front of it, the shutter fires off, clicking its picture. In this manner, scientists have garnered tremendous insight into the secretive lives of animals.

In the 20th century, earlier versions of camera traps used strings attached to baits, which, when pulled, would trigger a flashlight camera nearby. Scientists in Michigan, US, used this to study foxes, blue jays, skunks and a host of other animals. Later, these cameras came with internal clocks and thermometers that could record the time and temperature when the picture was taken, to provide further insight into wildlife behaviour.

Camera trapping in India started with the work of Fredrick Walter Champion (abbreviated to FWC). He pioneered a technique called “Tripwire Photography”, where he would conceal a wire that was tied across a game trail in the forest. When an animal touches the wire, it sets off a flash camera, thus taking a picture. In a way, the animal took its own photograph. 

Sloth Bear image taken by FW Champion

Nowadays, while there are many types (infrared and LED, triggered and non-triggered), their baseline purpose and functionality are the same—an animal is detected, and a photograph is captured.

Camera traps allow one a peek into the several animals that live in a particular area. By placing a camera trap at an ideal location for an extended time, one gets pictures of most of the species that live there.

Me placing a camera trap

Sometimes, camera traps reveal animals scientists didn’t know lived in the locality. For example, camera trapping studies conducted by Dr Sanjay Gubbi in Cauvery Wildlife Sanctuary, Karnataka, India, detected the presence of the ratel (or honey badger), the first time the species was recorded in the state. Even species previously thought to be extinct have been “re-discovered through camera traps (like the striped rabbit in Sumatra).

These cameras are secured to trees in the field using chains or sturdy cables. In elephant country, they are often housed in a steel casing to reduce the risk of damage. These would be placed in strategic locations, like near dens, on carcasses, or along game trails, for they provided the best chances of getting images. 

A field sketch of a python cable, which is used to secure camera traps to trees.

Each location is marked on a GPS so researchers can return later when required. These locations are also imported into software like Google Earth, giving them a study area map.

These locations are repeatedly visited to collect the camera’s data. This can either be in the form of a pen drive or SD card. These are then analysed back at camp, and when the images of the target animal/behaviour are found, they are saved onto a separate hard disk. Finally, the cameras are removed after a defined period, and the researchers move on to the next study site. 

Data collection from a camera trap in the field

Camera traps guzzle up a surprising amount of power. Usually powered by AA batteries, a set of 6 is said to last a few days. Researchers need to regularly revisit the cameras to check the battery status. If dead, they replace them with a new set. 

An extensive camera trapping exercise (such as a tiger or leopard census) uses up enormous amounts of batteries. Rechargeable batteries are not viable, as field conditions are pretty poor and often without electricity. Moreover, charging batteries for 50+ cameras requires scores of plug points, further compounding the problem. Solar charging isn’t practical either. Currently, there is no viable alternative to using disposable Duracell batteries.

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Now, animals like tigers and leopards have individually distinct markings. This means that each animal’s stripe or spot pattern is unique (it is comparable to each human having a different fingerprint). 

No two tigers have the same stripe pattern. So by getting pictures of both sides of a tiger, it is possible to assign that individual an ID. Thus, in this manner, scientists can obtain images of individual tigers in an area, which they can then use to estimate the area’s tiger population. (Counting tigers using camera traps in India was pioneered by Dr Ullas Karanth)

Tiger behind tree. Shot in Karnataka, India.
Each tiger has a distinctive stripe pattern

Scientists use the capture-recapture method to assess the population of individually marked animals in a given area. Simply put, they first conduct a survey where they count as many animals as possible, assigning each with an ID. Then, they re-conduct the survey and determine how many previously identified animals turn up. Then, they get a reasonably accurate guess at the total population using statistics. 

Until recently, remote cameras were used only to study terrestrial animals. But now, researchers use them to understand the behaviour of arboreal and marine life as well. 

Camera traps have aided conservation in more indirect ways as well. These devices often capture human movement in protected wildlife areas, valuable information to the concerned authorities. Scores of poachers have been apprehended thanks to their images from these cameras. Pictures of livestock, feral dogs and animals with snares around them provide proof of illegal activities going on in protected areas.

But all of this has a cost. Some animals don’t take well to foreign objects in their environment. Elephants regularly destroy camera traps, either by smashing them with their feet or by yanking the tree to which it is tied. Sloth bears gnaw at the casings while termites try to build. People, especially poachers and woodcutters, drop rocks on it or snap the cables and steal them. Each camera costs around 15,000 rupees (180 USD), and each loss is expensive.

I find camera trap technology fascinating. For one, it combines two passions of mine – ecology and photography, using it to unearth secrets of our natural world. Through it, we have obtained images of extremely rare behaviour. Animals hunting, feeding, fighting—you name it. Getting such images would be impossible through conventional methods.

Me checking if a camera trap works by triggering it

I have participated in camera trapping exercises, the most recent being the leopard monitoring project in MM Hills Wildlife Sanctuary carried out by Dr Sanjay Gubbi and Hollemathi Nature Foundation (HNF) in Karnataka, India. I walked dozens of kilometres through the forest, setting camera traps in the remotest of locations. 

While I can’t reveal any details, I can say that doing hands-on research truly gave me a greater appreciation for the craft and the people behind conservation.

Read about the long term study on leopards conducted by Dr Sanjay Gubbi in Karnataka, India.

For more information, read “Camera Traps in Animal Ecology” by Allan F. O’Connell ● James D. Nichols K. Ullas Karanth.

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Published by Ishan Shanavas

I am a young adult, interested in nature, photography, art and culture. An aspiring polymath, I share my learnings through my blog. I also include insights from my favourite books.

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