As part of research projects, researchers often need to capture an animal so they can either fit it with a tracking device, take blood samples and other measurements, or simply relocate the animal.
To do this they need to tranquilise the animal. Before the animal can be tranquilised however, the researcher has to do two things.
With a new research project, the researchers are likely to want to capture a number of animals. For instance if the project is to look at the density of leopards in a certain area, the researcher will want to capture as many leopards as possible to identify and possibly collar them. To do this, the researcher has two main choices - either hunt for leopards constantly and try and get close enough to them to dart them, or to use boxtraps to capture them. The first option is often very impractical - for instance nocturnal predators such as leopards are difficult to get close enough to for a researcher to be able to dart them, so the option of using a box trap becomes preferable.
Box traps are small cages with a door at one or both ends. The doors are connected to a trigger mechanism attached to a rocker plate on the floor of the trap. An animal walking into the trap steps on the rocker plate and this releases the doors which drop down trapping the animal inside the cage ready for the researcher.
The researcher will first select suitable locations to site one or more box traps in the study area. They look for locations where the target animals are likely to visit (e.g. near a small waterhole), and position the trap there. The trap is then camouflaged to make it less obvious to the animals - a large metal cage sitting in open flat land stands out and is likely to be avoided, whereas one with bushes around it and dead branches used to break up the shape of it is less likely to stand out. The researcher will probably then use some bait to attract the animal into the trap e.g. to catch a leopard some fresh meat would be placed in the trap. If the researcher is likely to leave a trap without checking it for several hours during the heat of the day, it is important that they leave some water for any animal that enters the trap to avoid it becoming dehydrated, and the top of the trap will normally be covered to give the animal plenty of shade.
Once one or more traps are set, the researcher simply has to keep checking the traps at regular intervals to see if any animals have entered the box trap and been captured. If an animal has entered the trap and is the species that the researcher is targeting then they can use a blowpipe or dart gun to tranquilise the animal ready to take their blood samples, measurements or to fit a collar. If the animal is an undesired one (e.g. a hyena entering a trap when the researcher is only studying leopards) then depending on what species it is, the researcher can either simply open the door to release it (e.g. if a springbok had been caught in the box trap), or can tranquilise it then open the door, remove the animal and leave it to regain consciousness and walk away.
It is important that box traps that have been set are checked very regularly to ensure animals are not left in a trap for long as it is an extremely stressful time for the animal and animals that are left in a trap for several days are likely to injure themselves trying to escape from the trap. When trapping nocturnal predators it is best for the researcher to ensure that they check all the traps every morning and then deal with any animals that have been trapped immediately.
By using several box traps in an area over a period of time and by varying the locations of the traps at intervals, the researcher should be able to capture a number of animals for them to study and release.
Fitting radio collars to animals that have been caught using box traps allows the researcher to then track their movements in detail over a period of time, and they only normally then need to trap that animal again when the collar needs replacing.
© Predator Conservation Trust.
