Camera traps I
- The Basics -
In this article, you learn more about camera traps and some of the basic concepts. The last section gives a brief introduction on what can be done with camera traps and how to use camera tapping in a survey. This is the first article of a series on camera traps. The next articles will go a bit more into detail, whereas this article aims to explain the basics.
First of all, there are a couple of ways to study animals in the wild. Obviously, you can study them by direct observations. This is very intensive and definitely for more elusive and rare species, it’s hard to get sufficient data. Another option is to look at signs animals leave behind, this is so-called tracking and is usually based on finding footprints in the substrate (snow, sand, …). But it also brings a lot of uncertainties with it. As an addition to these non-invasive methods, where animals are not touched, there is the possibility to trap animals. For example, mice and small rodents can be trapped and marked individually for a, so called, capture-mark-recapture study. Larger animals can be fitted with a VHF or a GPS collar, this is basically a collar which fits around the animal’s neck and is able to be sent out signals for locating the animals. This gives away the whereabouts of the animals captured. It is focused on the animals captured, and will a couple of animals will be used to extrapolate some parameters to population levels.
Additional to these methods, in the last decades, camera trapping is becoming more and more popular in scientific research on animals. The basic idea is animals are triggering cameras remotely, without the need of people to take a picture. This research strategy started with the development of cameras. The basic idea is the animal itself will trigger the camera and the animal is basically taking a selfie. In the early days, they used ropes. Animals passing by were touching the rope and on its turn, will trigger the camera to take a picture. In the past, they also have used active infrared beams, where they connected a device with an infrared beam to a camera and if this beam was broken, a picture was taken. This technology is still used, but not that much anymore. Technology is evolving quickly and nowadays these cameras and all the trigger equipment are changed for a little box, a camera trap.
As mentioned before, camera traps can work remotely after initial set up. The advantage of a camera trap is that it can be left in the field for months, and is working 24/7. The limitations can be found in battery life and storage capacity. But in general, it’s less effort for collecting more data. Of course, they have to be checked regularly to collect data (pictures/videos) and to check on battery life and change batteries if necessary.
Additionally, some camera traps are fitted with a SIM-card holder so photos can be sent straight to a computer. Of course, for this option, mobile phone coverage is needed.
The main differences between camera traps on the market are the lens (resolution) and the trigger speed. The trigger speed is a measurement for how fast after the movement sensor detected a movement, a picture is taken.
Camera trap – Settings
The market of camera traps consists of a variety of different types with different specifications. Here is a list of the main settings you can adjust or need to think about when using camera traps.
Photo/Video/Hybrid – Nowadays, camera traps can not only take pictures, but also videos. Some models are even able to do a combination of pictures and videos, which is indicated with the term ‘hybrid’.
Quality/Length – As with all technology, the resolution of the pictures or the videos is important. These two parameters are important to consider if you have limited storage space on your SD-card. For example, a video of 60s will be a larger file than a video of 10s.
Flash: White/IR (Infrared)/Dark IR – To decrease the disturbance to animals, researchers came up with Infrared (IR) flashes. The disadvantage is they give a black and white picture as outcome. Several projects are still using white flashed, definitely those who want to make use of individual identification (by using spot patterns on coat). Within the rage of IR flashes, there are differences in ‘visibility’. A normal IR flash is still visible for the human eye from about 10m. They developed a dark IR flash. This flash is generally not visible by the human eye, although it is visible if you put your eye very close to the flash.
Date/Time – Setting up the date and time correctly at the start of the survey is crucial. This gives the opportunity to check on temporal variation patterns.
Camera trap – What to solve
As mentioned before, camera traps are a non-invasive method with no influence on the animals. Although I also mentioned white flashes can influence the behaviour of the animal, as well as the IR flashes. Additionally, camera traps usually still make sounds when taking a picture. Definitely, when going from night to day picture (IR picture or normal picture), there is a filter moving in front of the lens. This all being said, camera traps are more or less non-invasive and have no massive influence on animals.
I hear you think, it all sounds nice, but what questions can you solve with it? First of all, you can find out what animal species are living in a specific area. This is better known as a presence/absence study. But you can do more with it. There are methods to estimate densities, although it’s still a field in progress, a lot is possible with it. For example, the number of pictures of a certain species per 24 hours could be a good parameter for relative abundance. I will discuss this complex matter about density estimations in a future article. If you are interested in stories from the field around camera traps, definitely check out my blog about Canada, South Africa (South Africa part) & Belize.
As time and date are provided with the picture or video, it’s possible to see when different species are active. Do they roam around all night, or do they use specific times at night? Maybe to avoid other species. During my volunteering in Canada, the project was focused on the question if Grizzly bears were still using trails used by humans (for recreational use). Videos, on the other hand, given the option to study more in debt behavioural questions. As videos often record sound as well, this gives even more options…
There is still a lot to think about, for example, does it matter if you put a camera trap on a random position or better on a road? On a road, you are more likely to get more data, but maybe some species are more likely to use the road than others. Or species use roads at different times during their active time…
The above video comes from the WWF website telling the story of camera traps in India. Check out more on their website.
I hope this article gave you a bit more insight into camera traps. In the future, I want to tackle more issues on camera traps, as I think it’s a great way to study wildlife. You can also find a couple of videos I made with my Bushnell cameras in my small article about Urban Wildlife. And if you are considering buying a camera trap, definitely check my Bushnell NatureView review. Another website with a huge amount of camera trap reviews is Trailcampro (not an affiliate link).
If you want to know more about camera traps and methodology and such, there is a lot of good information available online. Although there are 2 books I really enjoyed reading and give plenty of information about camera trapping ( The first 2). I heard good comments about the last one with the dog on the cover.
DISCLAIMER: The links below (camera traps and books) are affiliate links. This means I get a small commission of you pursuit a product through those links, without an extra cost for you. If you have additional questions, don’t hesitate to get in contact.
Camera trap Literature
If you are interested in camera trapping, definitely keep an eye on the website and/or subscribe to our mailinglist. Also have a look at the blog post ‘Urban Wildlife in Belgium: camera trap footage’.
Furthermore, most of my projects I’ve been involved with have been using camera traps. You can find an overview of these projects here.