Within the metapopulation it is often necessary to capture and immobilize wild dogs, whether it is to translocate individuals, fit or remove radio tracking collars, collect tissue samples for analysis or remove snares.
Only qualified veterinarians can legally handle and administer the drugs necessary to sedate an animal. It is obviously not safe, or even possible, to approach wild animals and simply administer a tranquilizing injection. The use of a dart gun (or blow pipe if one can get close enough) allows administration of the sedating drugs from a distance. The drugs used to sedate an animal are schedule 7 and, as mentioned above, must be handled and administered by a qualified veterinarian. Specific doses and spectra of drugs are required to safely immobilize animals. The margin for error is very small. Vets will usually bring their own dart gun and darts as well as the required drugs to the darting. The dart, a ballistic syringe loaded with the immobilizing drugs and a hypodermic needle, is propelled from the gun by means of compressed gas. A feather-like tailpiece stabilizes the dart in flight. By interchanging tailpieces the same syringe can be used in a blow pipe. The needle itself may be plain or collared. The collared needle has a barbed circumferential ring that improves retention of the dart and ensures that the full dose is administrated. On impact the plunger within the syringe injects the drug into the animal. The gun is relatively quiet, thus reducing the potential stress caused by a loud discharge, and has a pressure valve to control dart velocity.
The actual darting procedure depends on the individuals to be darted. If the individuals are completely habituated to a vehicle it may be possible to simply drive up to them, aim the dart gun and fire the dart (into their rump or shoulder if possible). It is, however, more likely that the darting process will require a great deal more planning, cunning and finesse. Wild dogs will often respond to a carcass or bait tied securely to a tree or dragged by a rope behind a vehicle. If the pack feeds on the carcass the dogs may be distracted enough to approach sufficiently close in a vehicle to successfully fire a dart into the desired individual(s). Using a carcass has the added benefit of keeping the rest of the pack occupied while working on the sedated individual(s) and ensuring that they will still be in the vicinity when the sedated dog(s) recovers. Unhabituated wild dogs can be very wary of vehicles and humans, making this kind of darting nearly impossible. In such cases other methods of capture can be attempted (see ‘Cage capture’).
Once the dart has been successfully administered the individual must be carefully watched to see where it falls asleep, as it is their natural instinct to run once hit by the dart. Once the individual lies down and stops moving it must be approached with caution to ensure that it is completely sedated. A number of unfortunate vets have been seriously injured by animals that, although they appeared fully sedated, were, in fact, not yet completely asleep.
Once the individual is fully unconscious work on the wild dog can begin although a further dose of drugs may be needed to keep the wild dog sedated for the required amount of time. Once work is completed the vet will either administer a reversal drug to quickly wake the individual, or it can be left to wake up as the drug wears off. The individual is particularly vulnerable to attacks by other animals at this time and should be watched until it was recovered sufficiently to walk or run away. If the wild dog was darted to be relocated then it will be placed in a transport crate or unit (see ‘Transport of wild dogs between reserves’) and usually left to wake naturally while in transit.
When individuals can’t be darted from a vehicle, cage capture or ‘cage traps’ may be used. Cage traps are indiscriminate and do not allow for specific individuals to be captured. These traps are small cages with a door at one, or both, ends. The doors are connected to a trigger mechanism which, in turn is attached to a plate on the floor of the cage. When an animal walks into the cage to retrieve the bait it steps onto the plate which activates the trigger resulting in the doors dropping down and trapping the animal inside. A blow pipe or pole syringe can then be used to administer the sedatives to immobilize the animal.
Choosing the best location for the cage trap to catch a wild dog can be difficult as wild dogs settle in a different area each day except for the three months of the denning season. In addition, unless starving, wild dogs are unlikely to be attracted in to a cage by bait. This method of capture, although frequently used to catch other carnivores like leopard and cheetah, has not seen much success in wild dog capture.