Camera traps fooled by sneaky sloths
Camera traps and trail cameras are commonly used outdoors for wildlife research and they are now also playing an increasingly important role in the conservation and preservation of endangered species. These little motion-activated cameras have been instrumental in some of the most important conservation discoveries in recent years, including the identification of new species and providing living proof of species once thought to be extinct.
It’s a trap!
These hidden cameras are particularly useful for monitoring rare, elusive, shy and otherwise difficult to observe species in the wild. They are essentially made up of a digital camera connected to an infrared sensor that, by detecting differences in temperature, can identify objects that are both warm and moving (like an animal, for example). For this reason, camera trapping works very well for warm-blooded mammals and birds, but less well for reptiles and amphibians as their body temperature closely mimics that of the environment. When a warm animal moves in front of the infrared sensor, this triggers the camera and it will take a photograph or start recording video (or both)! These rugged cameras can be set up in the field and left for weeks at a time to capture the activity of any passing animal.
The good, the bad and the ugly…
By using camera traps like this it enables biologists and conservationists to easily collect ecological data and photographic evidence of elusive and often critically endangered species at little cost and with minimal disturbance. By remotely monitoring wildlife in this way it can allow us to spy on some of the rarest events in nature – events that just wouldn’t happen if there were any humans around. We can see exactly what animals are doing, where they are and how large the populations are. Camera traps that send real-time images via phone / satellite networks are also proving to be a very valuable tool in the fight against poaching.
Despite the great potential that this technology offers, there are also numerous challenges to overcome when working with camera trapping. Firstly, wild animals do not always behave themselves around expensive technology. Larger species such as elephants, chimpanzees, bears and tigers are notorious for destroying camera traps if they discover them. In the Costa Rican jungle ants are also partial to building nests inside unattended camera traps, and if a spider decides to makes its web in front of the lens then you can forget any prized images. Humans can can also be equally mischievous, with camera trap theft on the rise! But perhaps the biggest problem is leaving electronic equipment outside for Mother Nature to play with. We speak from experience here. In the jungle environment we face 100% humidity on a daily basis, coupled with scorching heat and monsoon rains. Even the most waterproof cameras don’t last long. Biologists working in the tropics often resort to inserting silica or tampons inside cameras to absorb humidity!
A sloth shaped problem
We love working with sloths, but their characteristics do make life difficult. Cameras that are designed to detect warm, moving animals do not perform very well when pointed at a slow, cold sloth.
Their careful and steady movements are subtle enough to go unnoticed by the rainforests greatest visual hunters (big cats and harpy eagles) and so the motion sensors on many camera traps simply do not pick up the sloths slow movements. To further complicate the situation, sloths have a notoriously low and variable body temperature compared to other mammals. For this reason they are often likened to reptiles as their core temperature closely follows the that of the environment. For a camera that relies on detecting temperature differences, this is not ideal.
We have had a great deal of trouble finding a camera trap that will get triggered by a sloth in the wild. Some zoos and rescue centers have had success using camera traps within their captive exhibits, but the environment inside a zoo is very different to the rainforest. Firstly, the ambient temperature tends to be much lower in a zoo which means that the sloth appears warmer. Secondly, a camera trap placed inside an enclosure is often much closer to the action. In the tropical jungle habitat we will be lucky to get a sloth passing by within 10 – 20 meters of the camera. And finally, captive sloths living in zoos tend to move faster than a wild sloth creeping through the jungle due to a lack of fear and predators. For example, we know that wild sloths move faster at night because they are less visible to predators!
And finally a solution
This situation may seem ridiculous, but the sloths inability to trigger camera traps is making our work much harder. Whenever we install a Sloth Crossing canopy bridge we always install a camera trap nearby to monitor the use of the bridge by any animals. These bridges are built to help sloths safely move between fragmented habitats in urban areas (without risking death from road traffic collisions, dog attacks or poaching) – but it is difficult to know if the bridges are a success without any evidence of sloths using them!
To solve this predicament, we sought the camera trap expertise of Nature Spy: a non-profit organisation that aims to research and protect wildlife whilst engaging local communities. They gave us a tutorial on how to optimise the chances of the camera trap triggering, and then generously donated two camera trap models that they thought might work. We currently have both of these cameras installed on Sloth Crossing bridges in the South Caribbean, and in a few weeks we will check the results. Huge thanks to Nature Spy for all of their assistance and we will keep you updated on any sloth sightings!