San Diego Zoo Wildlife Academy
The practice of capturing wild animals is as old as human existence. Methods for animal capture predate recorded history, and were largely predicated upon communities’ need for food and clothing. Today, the reasons for the capture of wild species are much more diverse, and include wildlife management efforts, general animal control, damage and disease control programs, population size and other research.1 Many areas of animal capture are highly regulated in most nations, particularly those associated with protected or endangered wildlife species.
Aspects of animal welfare should be of concern regardless of the reason for capture, and the efficiency of any capture method is a critical component of wild animal capture. The most successful animal capture programs have been the result of the efforts of experienced wildlife biologists, wildlife managers and veterinarians who have studied and tested numerous methods over many years.
Wildlife Capture Methods
In the case of wildlife capture, two types of are typically discussed: physical capture and chemical immobilization. Physical capture involves the use of devices such as traps, nets and snares which restrict an animal such that it can be handled or chemically immobilized. Chemical immobilization involves the direct use of sedatives and/or anesthetic drugs to render an animal unconscious or docile enough to be safely handled prior to capture. Both of these methods effectively result in the physical capture of an animal.
The type of capture methods depend upon the species, need and often the conditions under which the animal will be captured.
Some of the physical capture methods in common use include:
Catchpoles—A long stick with a cabled loop on one end that can be tightened via an integral mechanism.
Nets—These come in many forms, the most common being throw nets and hoop nets. A throw net is tossed over an animal, while a hoop net is attached to the end of a long handle and is used to scoop up the animal. Netting systems for larger animals, or to capture large numbers of animals such as birds are also commercially available.
Live traps are effective devices for capturing many species, and are widely used by wildlife managers and animal control officers. Variations of live traps include cage traps, multiple capture traps and foothold traps.3
Foothold traps restrain an animal by holding the foot. These are still used by some wildlife services for wildlife damage management, mostly involving wildlife that are causing damage to property, agriculture, and natural resources or protecting human health and safety. Because of the cruelty inherent in the use of steel-jaw traps (a type of foothold trap), these have been banned in many countries, and in several U.S. states.4
Corral traps are large, temporary fenced enclosures with an entrance that can be closed after birds are guided into the trap. Birds are typically driven into the trap by a team of handlers.
Funnel traps are traps consisting of a wire cage or enclosure with one or more funnel shaped entrances which the birds can enter, but have difficulty exiting.
Dive-in traps are usually baited traps that are effective for capturing aquatic diving birds. These traps are only effective in wetland habitats, but may be used in permanent water bodies of adequate depth or tidally influenced wetlands.3
Chemical Immobilization involves the use of sedative and/or anesthetic drugs to immobilize an animal to facilitate capture. In most cases of wildlife capture, drugs are administered via remote delivery, since this permits the targeting of specific animals and allows the delivery of anesthetics from a distance.
Animal Identification Methods
For the purposes of animal management, conservation and research, the proper identification of captured animals is essential. This enables the manager or researcher to keep comprehensive records for a variety of reasons (e.g., migration data, breeding data). There are two basic types of identification: non-permanent and permanent. Non-permanent identification can include paint, chalk and certain types of tags. Permanent identification includes tattooing, ear notches, radio collars and microchips. In the case of captured wildlife, permanent identification is used in the vast majority of instances.
The efficient maintenance of data for certain wildlife management and research efforts often requires permanent identification systems. Such systems are typically selected based upon the number of animals to be captured, the purpose for identifying the animal(s), environmental conditions and regulatory concerns. Several systems of identification are available for these purposes, including:
Tattooing is a permanent method of identification, however it can be impractical in the field. Tattoos are also not easily viewed on many animals and may require other complementary methods of identification, such as an ear tag. On older animals, some tattoos may also be difficult to read.
Ear notching is commonly practiced in identifying some animals on farms, such as goats. This has the advantage of being visible from a distance, allowing identification without the necessity of catching the animal. For these purposes, ear notching pliers are used to put “V”-shaped notches in the edges of the ear.
Ear tags are an easy way to permanently identify many species of wildlife, as the tags can be constructed in a wide variety of sizes. Unfortunately, they can break or be ripped out of an animal’s ear. Before putting in the ear tag, it is important to record what ear tag number is assigned to a given animal.
Bird banding is one of the oldest and most important techniques used for studying and identifying birds. In order to identify and keep track of individual birds, managers or researchers put aluminum or colored bands on birds' legs. Each band is engraved with a unique set of numbers. Because the chances of encountering a banded bird again can be low however, banding data is of limited use when it comes to tracking migratory birds throughout their annual cycle.5
Radio collars consist of a wide band of belt-type material (e.g., nylon) fitted with a small radio transmitter and battery. The transmitter emits a signal at a specific frequency that can be tracked from distances. When trying to locate a particular collared animal, the manager or researcher inputs the appropriate frequency into the receiver and listens for the signal emitted by the transmitter. Despite the cumbersome appearance of the apparatus, extensive studies in game reserves and national parks have shown that radio collars have no negative effects on the behavior or survival of individual animals.
Passive Integrated Transponders are tracking tags that have an internal microchip which is activated when it passes close to a special antenna. The antenna is connected to a computer that records the identity of the tag and the time that it passed by the antenna. These are commonly known as “microchips” or “PIT tags” and are identical to those used to keep track of pet animals in many areas. An advantage of this tag is that it does not need a battery, so it can last for the entire time that an animal is wearing it. They are also very light and inexpensive. Unfortunately, they have to be very close to the antenna to transmit data (a few inches to a few feet away).
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!
1Eltringham S.K. (1978) Methods of capturing wild animals for marking purposes. In: Stonehouse B. (eds) Animal Marking. Palgrave, London.
2Schemnitz, S., et. al. Capturing and Handling Wild Animals. (2009). USDA National Wildlife Research Center – Staff Publications. 1191.
3Animal Care and Use Committee (1998) Guidelines for the Capture, Handling, and Care of Mammals as Approved by the American Society of Mammalogists. In: J. Mammology 79:1416-1431.
4Hubert, W., et. al. Passive Capture Techniques (2012). Nebraska Cooperative Fish & Wildlife Research Unit, Staff Publications, 111.
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.
Our pharmacists are also encouraged to develop strong working relationships with our veterinarians in order to better care for veterinary patients. Such relationships foster an ever-increasing knowledge base upon which pharmacists and veterinarians can draw, making both significantly more effective in their professional roles.
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