Relatively few small carnivore species have been intensely studied, which accounts for our general lack of knowledge about these animals. There are a wide variety of research techniques and methods that are available for scientists and naturalists to study animal species, and below we have described some of these.
Some small carnivores, such as certain species of mongooses, live in open habitats and are active during the day, which allows field scientists to observe their daily behaviour and movements from a fairly close distance, especially if a group becomes habituated to the presence of humans. Obviously, this technique is not suitable for those small carnivore species that live in dense vegetation, such as rainforests, or are only active at night. However, some nocturnal small carnivores can sometimes be detected by slowly walking along a trail or logging road at night and scanning the undergrowth with a powerful torch or spotlight to pick up the bright, reflective eyeshine of an active animal. Such information can confirm their presence in a region, or in some specific habitat.
Radio-telemetry and camera trapping
Since the mid 20th century, field scientists have been using radio-telemetry to track the movements of animals in the wild. This technique involves two devices: one that emits a signal and another that detects it. The first device is a transmitter that is attached to an animal and which sends out a signal in the form of radio waves, just as a radio station does, and for most small carnivore species, this transmitter is attached to a collar that is placed around the animal’s neck. The second device comprises a receiver and directional antenna that picks up the signal, just like a home radio picks up a station’s signal, and this receiving system can be carried by a field scientist while walking around the study area, or placed in a vehicle or plane. Global positioning system (GPS) transmitters have now been developed that use a network of orbiting satellites to automatically record the locations of an animal at specific time intervals, which can then be downloaded to a computer or other mobile device. This new technology produces a large amount of data, and greatly minimises the time that researchers need to spend in the field. Radio-telemetry can be used to yield valuable information on a small carnivore’s movement patterns, the size and use of its home range or territory, which type of habitats it prefers, its pattern of activity, and its choice of rest or den site. However, this is an invasive technique in that to attach a radio-collar to an animal, it must be trapped and anaesthetised.
Camera trapping is a method for capturing images of wild animals in the wild, and has been used in ecological research for several decades. A camera trap is a remotely activated camera system that is triggered by a motion or infrared sensor – as an animal passes in front of the camera, images are automatically recorded. Originally, cameras with print film were used, but these have been replaced with digital models. Camera traps are often attached to trees, and placed close to trails, or near sites that may attract animals, such as a waterhole or animal carcass. Many camera traps can set up across a study area and be left in place for weeks or months, only requiring periodic checks to download images and change spent batteries. Camera traps are particularly useful for detecting rare and elusive species, and a great advantage is that they can record a large amount of data with very little disturbance to the local animals. Camera trapping can be used to detect which small carnivore species are present in an area, record their behaviour and activity, and indicate which habitats a particular species prefers. Also, if individuals can be identified on images using their distinctive body patterns, it is then possible to estimate a species’ population size within the study area.
Up to until now, not many small carnivores have been studied in the wild, and for several species, we only have a few records of where they have been found. Over the past decade or so, computer modelling techniques have been developed that can use this limited field data to learn more about a species’ distribution and ecological niche. One such technique is called ecological niche modelling, which uses a computer program to combine location records with environmental information to predict where a species is likely to occur. These distribution maps can be very useful for conservation purposes, and for determining where future field surveys and research studies should be focused. Modelling analyses can also be used to make predictions for future, such as the impact of climate changes.
Recent genetic studies have shed much light on the taxonomy and systematics of mongooses. Small samples of hairs, tissue and blood are taken from mongooses in the field (either from trapped animals, road kill, or hair traps), or small amounts of material are removed from the bones or skins of museum specimens. These samples are treated with chemicals to extract the DNA. Fragments of genes that are obtained from this DNA are amplified, and then sequenced, using a sequencing machine, to determine the base pair sequence of the genes. Computer programs can then compare the sequences of genes between individuals and species, and determine the genetic relationships between different individuals, populations or species. This helps tracing their evolutionary history.