BATS

9.1 Capture and physical restraint

All bats are capable of inflicting bites and scratches and are known reservoirs of zoonotic pathogens. Only prop­erly trained personnel who have been vaccinated against rabies (with demonstrable protective antibody titres) and using appropriate PPE should handle bats (see Chapters 16 and 42, Olsson and Woods (2008) and Heard (2014) for additional information).

Free-ranging pteropodid bats are captured when they return to their roosts in the early morning using mist nets set on high poles (up to 13 m). Nets must be con­stantly monitored and once several flying-foxes are entangled, the nets are lowered to free and retrieve the animals. An alternative technique uses ropes pre­positioned in trees adjacent to the roost. On the morning of the catch, a mist net is attached to the ropes, spaced 15-20 m apart and hauled up into position, to ~15-25 m above the ground. Two mist nets, one placed above the other, can be connected using string, to double the catching area (W Boardman pers. comm.). Flying-foxes can also be trapped using very large harp traps sus­pended on yacht masts with a catch bag at the base that the animals slide into. These traps do not need to be constantly monitored (NHMRC 2014). The advantage of harp traps is there is no need for the disentangling required with mist nets. Smaller insectivorous and car­nivorous bats are best captured in harp traps (Fig. 9.9), which are set overnight and checked in the morning. Bats fly into the fishing line of the harp trap and slide down into a protected holding area at the base of the trap. Once caught in the trap, animals tend to be calm and may even go to sleep (NHMRC 2014; The Austbat Harptrap, Faunatech Austbat, Mount Taylor, Vic.). Mist nets set in flight paths can also be used for smaller spe­cies, but must be constantly monitored and animals removed immediately to avoid injury.

Bats held in managed care can be captured using hoop nets or if confined in a smaller hospital cage, hand- caught with protected hands (towel or gloves). Physical restraint may be adequate for simple procedures, but chemical restraint allows more thorough assessment with less risk to the animal and operator. Most insectivo­rous and carnivorous bats are small and adequately restrained by grasping over the dorsoventral thorax between finger and thumb. Many of these bats are deli­cate and can be injured with rough handling. They should be placed in small cloth bags for temporary hold­ing, short-term transport and handling for examination and anaesthetic induction with inhalation agents (NHMRC 2014). Ghost bats (Macroderma gigas) and diadem leaf-nosed bats (Hipposideros diadema) are an exception because of their larger size and long sharp canines. They are handled as for pteropodids. Pteropo- dids are restrained by wrapping with a thick towel while hanging. Once the towel is wrapped around the body to contain the wings and envelope the head, one hand is used to grasp the feet. The other hand then grips the head. Pteropodids accustomed to handling can be mini­mally restrained by the hindfeet and loosely wrapped in a towel. While restrained the bat can be briefly examined or an anaesthetic mask placed on the head for induction with inhalation anaesthesia. Handling time should be brief to reduce stress and prevent hyperthermia.

9.2 Chemical restraint

Hypothermia develops rapidly under anaesthesia if sup­plementary heat is not provided. The patagium is very sensitive to thermal injury and appropriate heat sources include circulating water blankets and forced air warm­ers.

Sedation is useful in larger bats to facilitate examina­tion and before general anaesthesia. Injectable anaesthetic agents are rarely used or required, other than for pteropo- dids, if inhalation anaesthesia is not available or if the animal is aggressive (see Appendix 3). IM injections can be given in the dorsal cervical, scapular, triceps or pecto­ral muscles (pteropodids only with care). Avoid the pecto­ral muscles in insectivorous and carnivorous bats as any trauma and scar tissue may affect flight (Olsson and Woods 2008).

Pre-anaesthetic fasting requirements are provided in Table 9.1. Inhalation anaesthesia using isoflurane or sevo- flurane in oxygen for induction and maintenance or sup­plementation and maintenance after injectable induction is the method of choice for bats. Induction is via mask or induction chamber. Anaesthesia is maintained via the mask or an uncuffed endotracheal tube. Intubation in larger bats is straightforward. Dorsal recumbency and a small-bladed laryngoscope allow better visualisation of the glottis (Heard 2014).

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