How Are Large Animals Captured?
Wild animals are regularly captured for a variety of reasons, some of which include conservation efforts, breeding programs, relocation and research. In areas in which the habitats of humans and wild animals overlap, the reason for capture can become one of animal control, which is usually influenced by factors relating to both animal and human safety.
Animal capture necessarily becomes more difficult as the size of the target species increases. As such, more refined techniques are required regardless of the need for capture, and issues of safety are more prevalent when designing procedures and protocols. In recent years, many new techniques for the capture of large animals have been developed. Some of these have come about for specific research or conservation objectives. Often, they represent either improved or modified versions of traditional capture methods.
Restraint and Capture of Large Wildlife Species
Today, large animals are captured through the use of mechanical devices (traps, snares and the like), the remote delivery of immobilizing agents, or drugs administered orally in baits. Well-designed commercial traps are available for a variety of species, and more are continually being developed as needs arise. Biologists, wildlife managers and animal control personnel often use such traps, as they tend to be both convenient and reliable, and an extremely wide variety of trap types and variations is available from commercial vendors.
While commercial traps and snares are widely used by biologists, wildlife managers and animal control personnel, as indicated above, these can become impractical if the target species is a large one.
Drop nets triggered by explosive charges have been used to capture deer and other cervids,while some versions have been developed that are triggered manually. Modified versions of drop nets have also been used in the capture of ungulates.1
Drive nets and drift fences are also widely used to capture both individual and multiple large animals, such as deer. These are similar to the more novel bomas, which are often used in helicopter herding in Africa. In this method, a helicopter and capture team drive animals into a large funnel of opaque plastic sheeting (a boma).2 Once inside the tunnel, the animals see the sheeting as a solid wall and don’t attempt to escape. Wildlife managers and game services often use all-terrain vehicles and helicopters as platforms for monitoring and tracking animals, and for operations in the field, such as chemical immobilization.
With regard to the use of nets in capturing large animals, Schemnitz, S. et. al. maintains that these should be placed in or near a drainage bottom, where animals can be herded downhill into the net, which can be concealed by terrain.1
Net Guns have been used to trap large animals for many years. These differ from cannon and rocket nets, which are typically used in the capture of birds, bats and smaller mammals. Net guns are frequently used from helicopters to capture animals as large as moose, and are one of the less stress-inducing methods of physical capture. The use of net guns from a helicopter was reported as one of the most effective methods for the capture of yearling and adult white-tailed deer in the field.1
Box and Cage Traps. While larger and of different configuration than the commercial traps used by animal control personnel for the capture of nuisance animals, box and cage traps are also used to capture larger animals such as deer. These typically consist of lightweight metal or metal frames with netted panels. In many instances, these are used for the capture of deer in urban areas.
Culvert traps are frequently used for the capture of bear. These traps are similar to a large culvert, with one open end and one closed end. The open end has a trap door, which is triggered to close when a bear takes the bait inside the trap. Culvert traps are sufficiently long that a bear has to move to the far end of the trap before it can reach the bait. The door closes quickly, well before the bear can make it back to the door. Culvert traps are generally held to be the safest non-chemical method to use for the capture of bear. The frequency of human-bear interactions and the encroachment of bear in urbanized areas have increased the popularity of culvert traps in recent years.
Chemical immobilization is one of the most reliable methods of restraining large wildlife species, and it has become a valuable tool in wildlife conservation research and management. Modern chemical immobilization is a humane method for the handling of large wild animals, and its improvement in recent years has drastically reduced the side effects of drugs and mortality. Further, the use of antagonist/antidotes for anesthetic agents is being more widely utilized to avoid the undesirable effects of drugs and for speedy recovery of wildlife species.
Remote delivery of anesthetics to large wildlife species is most often accomplished using a variety of syringe darts that are propelled by blow pipes or a variety of dart guns. These must be used only by experienced personnel, since the ideal target areas are limited, even on large animals. Dart guns range from very heavy duty rifles that use a .22-caliber system, to very lightweight pistols that powered by air or CO2. Dart types range from lightweight air-pressured systems to charge-powered injection systems.
Interested in learning more about safe capture? The San Diego Zoo now offers courses in safe capture techniques and best practices. Learn reliable, safe, and effective techniques for the species you work with and the scenarios you encounter!
1Schemnitz, S. et. al. Capturing and Handling Wild Animals. (2009) In: The wildlife techniques manual. Johns Hopkins University Press, Baltimore, MD: 232-269.
2wwf.org.
About NexGen Pharmaceuticals
NexGen Pharmaceuticals is an industry-leading veterinary compounding pharmacy, offering sterile and non-sterile compounding services nationwide. Unlike other veterinary compounding pharmacies, NexGen focuses on drugs that are difficult to find or are no longer available due to manufacturer discontinuance or have yet to be offered commercially for veterinary applications, but which still serve a critical need for our customers. We also specialize in wildlife pharmaceuticals, including sedatives and their antagonists, offering many unique options to serve a wide array of zoo animal and wildlife immobilization and anesthesia requirements.
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