In my previous article, I introduced the topic of camera traps. These tools allow you to capture images of things that may be happening when you are not there. Whether at home, in your garden, in a forest, or as part of a scientific or conservation project, it is important to choose the right model. To help you, I have written this little guide.
Some points to consider before getting a Camera Trap
The use of camera traps has grown considerably since their commercialisation at the start of the 1990s. Nowadays, people considering using a camera trap find themselves faced with ranges of exciting products available for purchase.
They also find themselves faced with many options for designing and customising their own trap systems. Technological advances in fields such as electronic engineering have been hugely advantageous, by enabling automation of their components, miniaturisation, and organisation of the traps in a network: all the attributes of modern camera trap system. These advances have allowed users to use these camera traps more efficiently and to collect samples from a variety of species under increasingly variable environmental conditions.
However, above all, these tools have also become more effective and more reliable. The cost of buying one, as well as their running and maintenance costs have significantly decreased, which has made more and more people interested. Also, while the general principle of a camera trap remains largely the same, today there is a whole variety of different models for different uses.
Camera traps are designed for diverse usages, under different conditions and for different species, which can make choosing the right model complicated. Their applications in scientific research include much more varied uses that may have different needs.
For example, a trap intended to detect a rare species in a remote zone needs to be robust, reliable and capable of taking photos weeks after being installed, whereas a trap used to observe the feeding behaviours of broods of birds in their nest needs to be silent, discrete and capable of taking many images in succession.
Other factors which can influence the choice of camera traps depend on the conditions, as well as the target species. Meteorological conditions and the climate are good examples: humidity on a tropical site creates different problems than those created by cold and the snow. Working in an urban area where vandalism and theft are serious problems requires camouflaging or “armouring” the equipment more often that working in a wild context. Similarly, camera traps used to study little birds (passerines) require the use of different trigger systems, light sources, focal distance than the settings required by the traps intended to study big mammals or reptiles.
The aim of the camera trap is the main question, in addition to the conditions of their use, and these should guide you towards which system to use. It is important to think carefully before opting for one camera trap over another. For example, according to some people, we should choose the camera trap based on the size of the species and the area being targeted. It is highly recommended that those without experience read the instructions that come with their new equipment carefully, and practice before using the camera in the field. There is no substitute for asking questions and working in the field with those with experience before embarking upon such a project.
Different types of camera traps and their applications
Camera traps can be divided into two categories: those which need to be triggered, and those which do not need to be triggered.
In the second case, the system includes a programmed camera to take images either continually, or at regular pre-determined intervals.
By contrast, camera traps in the first category stay inactive until they are triggered by an event, more often than not the presence of an animal. Their trigger system can be mechanic, like a pressure plate that the animal has to walk on, but more often the systems are equipped with infrared light. Some camera traps can also be designed to be triggered or programmed in order to create time lapses.
Camera traps without trigger systems are in general designed in two categories: the camera, and the energy source. They are more and more customizable and robotic to allow them to be controlled from a distance in order to make them pivot, zoom in, and zoom out.
Those which possess a trigger system are, on the other hand, made of many parts which function independently, or which are bundled into a single machine. These different parts can be infrared sensors, a camera, connected cables; a lighting system or additional sources of energy.
Being able to install them separately allows for a more flexible use of the camera tap and therefore better images can be obtained. Being able to install the infrared sensors separately allows you to adapt the position (distance, or angle) of the camera in relation to the target in order to obtain the best images. However, if one part doesn’t work, it affects the entire system. There are various reasons why this may occur: equipment that has been damaged by the animal, misalignment, battery problems, or problems with the sensors or the camera. A recurring problem seems to be that cables are gnawed or pulled by animals. However, some commercial camera traps of this type offer optional wireless connections between the various components, or reinforced cables. In any case, camera traps made from a single unit are less likely to fail in the field. They are also easier to transport, install and reinforce which is why it is recommended to choose this type when planning on using them in several remote areas.
Systems without trigger mechanisms
Camera traps that don’t need to be triggered are more applicable in the case of targeting animals that are resident and are visible in the open, or who move around a lot, or when it is important to have a continuous recording (for example establishing the presence or absence of the animal). In the case of targeting rare species or infrequent events; the use of such systems would require lots of energy and the analysis of the images would take far too much time.
Camera traps with trigger systems are practical when it is necessary to leave the device in the field for long periods of time, or for rare events. When these events of interest are frequent or continuous, these systems can prove to be more complicated and less reliable than the systems which function without a trigger.
Systems with mechanical triggering are particularly useful when the activity of interest requires the animal to be in specific locations, or when pushing a carcass or object. In this kind of context, infrared beam trigger mechanisms are more complicated and less reliable to use. But outside of these contexts these mechanical trigger mechanisms are useless. In which case, opting for the use of infrared beams could be more judicious, especially if the animal is too light or too fast.
Whilst it is important that the trap is not triggered by a different animal by mistake (like those below a certain size), we can resort to trigger mechanisms with an active infrared beam that the animal must cross, especially if the memory, or the quality of the image is limited. However, rapidly growing vegetation can cut the beam between visits, making this mechanism impractical. Wind, rain or snow can also frequently cut off the trigger beam or make the vegetation move. In cases where these conditions are common and also if a wider detection area is desirable, a passive infrared system can be opted for. However, in hot environments, this mechanism sometimes fails to detect the difference in temperature between the animal and the environment.
Camera traps casing
The camera trap casing can vary in colour, size and width. It can vary in durability, and also whether it is waterproof or not. For example, a camouflage one may be very important to reduce the probability of it being spotted by animals or humans, even if just to prevent it from affecting the behaviour of the targeted animals or being attacked, chewed, damaged or stolen. For animals, this involves having the information about their visual capacities (colour vision? Visible wavelength? Etc.) These factors depend on the species involved, but most of the time, it is also important that the casing can protect the device from animals. As previously mentioned, the cables and the cords are often eaten by little mammals, such as rodents. These cords can be reinforced by the manufacturer or even in the field with tin or covered by a repellent substance. Many mammals, like bears and elephants destroy the device when they discover it. This is what led to the production of commercial systems with this “armoured” casing.
Useful for avoiding malfunctions, waterproof casings are essential in rainy and humid environments. Placing a sachet of silicone gel inside can help to determine the waterproofness of the casing. If it changes colour, the box is not waterproof. In tropical regions, rubber seals must reinforce and seal the camera trap at each opening (the sensors, the screws) in order to prevent mould from growing inside.
This mould would quickly damage the electronic components, and oxodise the metal parts, for example. Mould can even develop from human perspiration, and form inside when the device is carried in a backpack. Furthermore, Japanese researchers believe that humidity is the biggest problem when using electronic equipment in tropical environments. What’s more, ants and termites settle in non-waterproof casings.
Camera traps are now specifically designed to be used in these regions. Someone even had the idea to hide one in a bucket of water to see which animals came to drink from it.
Deserts also pose problems. It is difficult to use most camera traps here, because they are designed to work up to 40°C. In very hot weather, most camera traps equipped with passive infrared light triggers are unusable because of the quality of their infrared sensors.
The smallest and most compact traps and casings are designed for nesting boxes, where there is little available space. Other casings are intended to reduce the noise produced by the device and avoid alarming the animal. Some even allow you to record sound with the images. Devices without trigger systems can even benefit from additional cables, allowing the camera to be connected to equipment located a hundred metres away to view or transmit images or power.
These traps can sometimes take surprising forms. Very complex and original systems have been designed and used. Let’s take the example of a system built specifically to target polar bears. The camera was included in a white-camouflaged casing, mounted on remote-controlled wheels and “armoured” like a mini-tank.
Programming and software
The majority of commercial camera traps contain software that helps support the system, by increasing functionality and providing additional data which is often useful in ecology. In general, these programs offer options to the user in order to optimise the sensors and obtain more information.
Data loggers, for example, record the date, the time and the temperature associated with recorded events. The recording of images can also be programmable. These programmes can save memory by pausing the camera after a few images, so as not to take too many images of a single event, or to take images of events which are only occurring in a desired time period. By only triggering the device at certain times (at night or in the day, for example) battery life is increased and energy is saved. For similar purposes, these options may include putting the camera on standby or modifying the recording options, such as pausing after taking a few photos. These options sometimes offer the possibility of decreasing or increasing the speed of the device: meaning the time between the triggering of the trap and the capture of the images. The sensitivity of the system can also be adjusted in order to target particular species. The more sensitive the device, the easier it would be to capture images of lighter and smaller species, like birds.
Sometimes, audio features can be activated on the camera traps, for example “stop whistles” designed to make the animal stop in front of the lens and obtain better images. Password protection and anti-theft settings can also be added to the list of possible options.
Modern camera traps can directly be programmed with a laptop. However, beware of poorly designed and overly complex programmes which can complicate the process and increase the risk of errors!
As you have just read, efforts have been made to reduce the energy needs of camera traps. This is because the power supply of a camera trap is a factor that can limit its use. Recently, efforts have been made to reduce their size whilst increasing their battery life.
Energy can be supplied by alternating current through a cord, and connected to a standard electrical outlet, or by a direct current provided by a battery or solar energy. Solar energy can provide a continuous current and avoid having to return to the trap too regularly. However, these systems are expensive and complicated to move around. They are nevertheless ideal for camera traps which are situated in the same place for long periods of time.
Systems which use an alternating current are less expensive and easier to use. However, using them in remote areas is not realistic. Commercial traps, with trigger systems essentially function with batteries. Conversely, most of the others run on alternating current. When it is possible to study or observe an animal near an AC power supply, these traps can provide valuable benefits, however electrical outlets are rare in remote areas.
Various types of batteries are used to power camera traps. Rechargeable batteries help reduce costs over time but are initially more expensive, and their battery life decreases over time. Therefore, they must be treated well, and can’t be used in humid areas without waterproof casing. Alkaline and Lithium-ion batteries are often favoured for their reliability, as they provide uniform power and don’t require any maintenance if they are discarded when empty (as long as they are non-rechargeable). In contexts where portability and durability are important, it is essential that this choice be made with care.
To this aim, everyone is required to make comparisons between different batteries and analyse the information provided by the manufacturer, and more reliably by searching the internet for the average watt per hour provided by the battery. It seems that batteries used for professional photography perform the best in terms of this criteria. It should be noted that fuel cells would perform equally well and are eco-friendly. Alongside solar panels, these interest some camera trapping professionals, but remain too expensive.
Photos/videos and lighting options
All types of camera traps can be associated with any time of camera. In terms of their characteristics, the rules and logic are the same as for any other camera and remains a matter of common sense. This may include shutter-speed, auto-focus (to get a clear picture of the animal, no matter how far away from the lens), resolution (be careful, as the higher the quality of the photo, the more space they will take up on the camera’s memory), the flash (for night shots), the infrared flash (decreases the risk of alarming the animal but provides images of a lower quality), the possibility of capturing images when brightness is very low like thermal imaging (much more expensive), the possibility of viewing images on site, making the device smaller… everything depends on what you want to obtain.
In cases where the animal targeted is dark, or even if you need better quality photos, an additional lighting system, or a strobe, can be added to the list, or be installed yourself, to obtain better images than with an ordinary flash. However, these consume more energy and also change the behaviour of the animal. Opting for videos rather than photos, and therefore for camera traps offering video capture, can be tempting, especially if you’re interested in animal behaviour or rare events. However, this requires much more energy and therefore uses up the battery faster. These energy needs for taking videos are no longer a problem when it is situated near to an AC power source or has access to solar energy.
Some researchers have reported effects of camera traps on animal behaviour, and potential biases in their data. Others have found that their systems have had little effect. In addition to the smell and the sound, flashes can scare them or make them avoid or destroy the camera trap.
The main alternative that has been found is infrared light sources that mammals and birds are often unable to see. Infrared light can also be used as a flash or be programmed to be activated at certain times. However, the picture quality is not as good as with other lighting systems.
Price, vandalism and theft
Camera traps sometimes have special features. They may have cables for fasteners and locks and may even be “armoured”. The same goes for cables which connect to them or provide power to them.
These precautions serve to avoid the risk of these systems being damaged by animals, but also to reduce the risk of vandalism and theft. Also, even though camera traps have become smaller and more affordable over time, and some people claim that competition between different brands will lead to a decrease in their cost, they still cost more than 100 euros apiece, (from 300 to 900 euros), and remain quite expensive for individuals. This has had the effect of attracting the curiosity or even lust of some less well-intentioned people. Those who use camera traps sometimes also need to deal with theft and damage, and so camera traps should be equipped to handle these risks.
[PHOTO: a photo of camera trap security casing, designed by Paul Meek and his colleagues, with one of their photos showing walkers inspecting the camera trap at Mylestom pit in New South Wales, Australia]
Reinforced and lockable casing is not necessary everywhere, but it is absolutely vital in certain sectors. It seems that malicious people will stop at nothing to access camera traps. Paul Meek, an Australian ecologist and researcher, is forced to engage in a perpetual arms race with the perpetrators. During one of their studies, monitoring 566 events, they obtained 23 photos of people interested in the trap, and no photos of the animal that they were interested in! When initially confronted with these thefts, he had to use his imagination to deal with the problem. In order to work in peace, Meek and his colleagues had to rack their brains to find solutions. They went so far as to develop and manufacture highly- armoured casings which were firmly anchored to the ground, and which they had to adapt at various stages: by adding an informative leaflet, camouflaging the camera trap, and even installing another camera above the camera trap to monitor it. Some solutions didn’t work, and others made the camera more easily detectable and thus skewed the results. Meek find it hard to comprehend the reasons for these failures, which include car ram attacks, or the use of tools from building sites. According to him, losses due to thefts and degradations of photo traps amount to more than 70,000 dollars for him and his American colleagues! To this day he is still looking for a solution to this never-ending problem. Some researchers are looking at more complex prototypes which are organised in networks and managed by scientists directly from their offices.