Noninvasive methods of monitoring
Some traditional, standardized methods for studying wildlife are actually not all that practical. For example, transect sampling involves the direct observation of animals along set routes, in order to extrapolate their abundances. This requires a large number of observations, with lots of demanding work and expense. Other methods that require live capture and handling of animals, such as tagging for individual identification and radio telemetry, are valuable tools for particular purposes.
However, those kinds of intensive methods may not work well with large animals (especially carnivores) that are observed infrequently in the wild. Obtaining large datasets for use in wildlife management can be achieved with simple, inexpensive and efficient methods to estimate species abundances.
The use of “noninvasive” methods, meaning those that don’t involve physical contact, is often preferable because they cause less (although not necessarily zero) disruption to animals. It makes common sense to minimize the disturbance to animals that we study, where possible. Common approaches include:
- Documenting tracks or droppings as evidence of the presence of carnivores — species tend to have distinct foot shapes and unique patterns of travel and marking behavior that provide an inexpensive, low intensity, and efficient way to monitor them.
- Analysis of DNA from samples that don’t depend on capturing animals, such as fur and fecal droppings that are collected opportunistically.
- Remote photography (also called “camera traps” or “game cameras”) to capture a permanent record of animals that may use a particular area.
Depending on the species and goals at hand, these methods can be useful for detecting the presence of rare or shy forest animals. They can also generate high-quality data for population studies, such as determining the occupancy of an area, and assessing fluctuations in abundance over time and space.
Remote cameras at the Santa Elena Cloud Forest Reserve
Early attempts at using remote photography to study wildlife date back a full century, to the early 1900s. They weren’t very successful because the equipment was expensive, heavy and awkward to use in the field. With today’s modern, rapidly advancing technology though, this has become an increasingly common and useful approach.
The Santa Elena Cloud Forest Reserve of Costa Rica’s Monteverde conservation area is using remote cameras to monitor mammals. The efforts are part of an environmental education program that involves local college students, providing them with hands-on conservation experience.
Recently, two new hidden video cameras (donated by Desafio Monteverde Tours in 2014) were mounted in the Reserve. The cameras are triggered by the movement of wildlife and then capture high-quality images or video clips. They are equipped with night vision, and thus will provide an exciting new look at the wildlife populations that occupy the protected cloud forest.
Camera traps are invaluable monitoring tools that allow researchers to investigate aspects of animal ecology that are otherwise difficult or impossible to observe. Because they are motion-sensitive, the cameras must be set up close to locations where species of interest are likely to visit, and positioned to best capture complete images of the animals. Knowledge about the natural history of target species can help to inform an ideal set-up.
Many advantages make this technique one of the most preferred noninvasive options for surveying wildlife. Remote cameras are so useful because they collect abundant information with relatively little effort, requiring less time and expense than traditional research methods. They can provide clear identifications of multiple species, including predators and prey, and may even be used to distinguish individuals, based on unique markings. The resulting data can be used to estimate abundances, with less introduced bias compared to some survey methods, because they don’t require a target animal to contact the monitoring device. Cameras are also helpful for recording the behaviors of elusive animals.
In practice, remote photography has been used commonly in bird research, to study feeding, breeding displays and nest predation. An exciting instance of their value is that remote cameras have been able to document the return of jaguars to Arizona, fifty years after the large cats were extirpated from the state. The resulting photos have apparently been well received, and have generated support for conservation of this majestic species along the US-Mexico border.
Disadvantages of remote photography are that some equipment can be complex to use, may experience malfunctions or limitations due to the life of batteries and film, and is liable to theft. The Reserve’s new cameras should last for months at a time in the field because they use little power unless they are triggered.
The use of some equipment, such as flashes, has also been shown to influence animal behavior, such as disrupting movement patterns. Another potential drawback is that remote cameras are thought to perhaps encourage poaching, if hunters can use them to scout potential areas for targets. This is not expected to be a problem in the Reserve, where animals are closely monitored and protected by park rangers.
Although there are some limitations to the use of data collected via remote photography, footage from the Santa Elena cameras should enable some interesting new insights about the Reserve’s fauna. We will report interesting observations here in future blog posts.