Chapter Five

LIGHTING
Whether a bat roosts under intense natural light or deep within the recess of a cave, light plays a significant role in many aspects of its life cycle (i.e., circadian rhythms). Light quality and photoperiods have been connected with the reproductive biology in a variety of animals (Farner and Lewis, 1971; Sadleir, 1969; Wurtman and Weisel, 1969; van Tienhoven, 1961; 1968), and temperate-zone species may be reproductively compromised without regulated photoperiods. Photoperiods are best provided by placing cages in rooms with natural sunlight. Light intensities and photoperiods can also be controlled with full-spectrum, fluorescent lights set on timers. Full-spectrum lighting (many brands available) is especially important when maintaining tree-dwelling bats such as lasiurines and most pteropodids. These animals roost naturally in sunlight, and may require ultraviolet wavelengths for vitamin D production. Nevertheless, all captive bats should be given the option of avoiding light during the daylight hours by providing them with appropriately designed roosts (discussed further under CAGING below).

Because bats are nocturnal, zoos often exhibit them on a regime of reversed light cycles. This allows the public to view the animals during their active period. For this purpose, a combination of blue and red bulbs works well to simulate moonlight. When maintaining bats under natural light/dark cycles, it is best to set timers so lights come on an hour after sunup and go off an hour before sundown. In this way, the change in lighting is gradual. When housing bats in rooms without windows, consider installing a dimmer switch or rheostat to effect gradual light changes. Bats must never be maintained in an evironment of constant light or dark.

TEMPERATURE AND HUMIDITY
Depending on the species and time of year, ambient temperatures and relative humidities for temperate-zone bats should be: winter - 72-74F (22-23C), 50-65%; and, summer - 78-82F (25-28C), 50-80%. Tropical bats should be maintained all year at temperatures ranging between 78F and 82F (25C and 28C), with a relative humidity of 55-90%. Use the low end of the temperature range during the animals' active periods.

To provide bats with appropriate temperatures and humidities, it may be necessary to house them in a separate room with a space heater and humidifier (fine mist humidifiers are best). This is particularly true when housing tropical species in the northern hemisphere. Additionally, bats should be maintained in cages that provide them with a temperature gradient so they may seek out their thermal preference. This is the temperature an animal selects voluntarily when a range of temperatures is available and, unless temperate-zone species are being hibernated artificially, they must always be given voluntary access to it. Cool retreats must also be provided. Never expose bats to drafts.

During the evening hours, red-colored lightbulbs can be employed to provide bats with a choice of temperatures. For example, a 250-W lamp can be mounted at one end of a flight cage (FIG. 22), and a 25-W lamp can be mounted on small cages (FIG. 23). Keep all heating devices on the cage exterior to prevent accidental burns. Because of the differences in ambient temperature and humidity requirements for tropical and temperate-zone species, avoid housing them in the same room.

Figure 22.  To provide bats in flight cages with a choice of temperatures, place a 250-W lamp, with a red bulb, overhead.

Figure 23.  A 25-W lamp with a red-bulb can serve as an added heat source for small cages (photo courtesy of the Pittsburg State University, Pittsburg, KS).

CAGING
Bats should never be housed in cages with ceilings so low that their heads are on or near the floor when roosting. Carpenter (1986) reported problems with flying foxes maintained in short cages. Their ears became covered with food and excrement which led to tissue necrosis.

The best cage substrate for all species is newspaper; however, paper with colored inks should be avoided as it may be toxic. Fruit bats and vampire bats produce soft, sticky feces, and products like sawdust, wood shavings, dried clay chips or corncob can adhere to wings and bodies if the bats crawl on the cage floor. Therefore, such products should be avoided. Insectivorous bats produce dry pellets, but they either catch their food in flight or glean insects from various substrates. To prevent them from accidently ingesting foreign particles, their feeding area should also be free of litter. Generally speaking, newspaper is the best substrate for indoor housing, and grass is ideal in outdoor enclosures.

Crevice-dwelling Bats
Longterm captive crevice-dwelling bats do not have to be housed in cages that allow sustained flight. Furthermore, if they have adequate room to exercise, and to stretch their wings without hitting the cage walls, they do not require flight time outside of their cages. In July, 1986, I placed approximately 30 big brown bats (Eptesicus fuscus) in an outdoor flight cage (FIG. 10) which contains two roost boxes measuring 2 X 2 X 2 ft. (61 X 61 X 61 cm) (FIG. 10, 11). During the first winter, many did not leave the roost boxes to feed during warm spells. After some died, I placed Petri dishes containing mealworms inside the roost boxes rather than in the flight-area feeding stations. After the second winter of being fed in the roost boxes, all of the bats confined themselves to the boxes permanently. Since then, they have not left the boxes even to visit back and forth between the two roosts.

In the northern hemisphere, it is expensive to maintain hibernating bats outdoors. Roosts must be equipped with heating and cooling devices attached to thermostats to prevent the animals from freezing during winter and overheating during summer. It is therefore advisable to house these animals indoors. Cages should have solid walls constructed of wood (e.g., 3/4-in. plywood) with horizontally grooved sides (FIG. 24). The wood surfaces help bats to maintain short toenails, and the sides must be grooved because bats cannot traverse smooth surfaces. The grooves should be from 1/4 in. (0.6 cm) to 1/2 in. (1.3 cm) apart, but never farther apart than 1/2 in.

Figure 24.  Because bats cannot climb on smooth surfaces, the sides of their cages must be grooved;  also, wood cages prevent overgrowth of bats' toenails.

Depending on the species, for each bat I recommend a cage size of approximately 3 ft. (91 cm) high by 1½ to 2 ft. (46 to 61 cm) wide by 1½ to 2 ft. (46 to 61 cm) deep. Cages should open in the front with 1/4-in. polyethylene plastic mesh (FIG. 25a) attached to the door frame. Avoid the use of wire mesh, which is corroded by urine.

Figure 25.  "Universal Cages (Figure 28) can be constructed with mesh of appropriate size for the species (available from Internet, Inc.)

Mesh size is important: mesh smaller than 1/4 in. cannot be cleaned properly; mesh larger than 1/4 in. may permit a bat to escape or become wedged and injured. Cover all sharp edges to prevent wing damage. Also, to prevent bats from suddenly flying out of their cages when doors are opened, cages can be constructed with two doors (FIG. 26). To secure doors, window-sash locks are best. The cage interior should be sealed with a medium [battleship] gray, semi-gloss, water-based wood finish.

Figure 26.  The "hard-sided" cage is ideal for a variety of genera including Eptesicus, Lasionycteris, Molossus, Nycticeius, Myotis, Pipistrellus, and Tadarida (photo courtesy of the Staten Island Zoo).

To provide crevice-dwelling bats with a place in which to hide, tilt a piece of cork bark in one corner of the cage (FIG. 27). Do not confuse cork bark with cork board; they are totally different products. Purchase a piece of bark that is nearly as long as the cage is high, or at least 2 or more feet (61+ cm) by approximately 10 to 12 in. (25 to 30 cm) wide. When cork bark cannot be obtained immediately, use lightweight, split firewood (hard, non-resinous wood only) or some other rough material, but remove splinters that can tear wing membranes. It is best to place the rough surface toward the cage wall. In this way the bat has a favorable perching site (e.g., a simulated crevice with an appropriate surface). When using bark stripped from a tree or log, rinse it with scalding hot water to kill any resident arthropods. Allow the bark to dry thoroughly before placing it in a bat's cage. To provide additional hiding places, drape a pillow case, laundry bag or T-shirt over the bark (FIG. 27). Even more hiding places can be created by hanging one or two pillowcases from the top of the cage (FIG. 27).

Figure 27.  The types, and placement, of cage "furniture" is important in reducing environmental stress.  The placement suggested here provides a wide variety of roosts.  To prevent injuries to bats, attach pillowcases to the cage with Velcro®, NOT tape or other potentially dangerous items.

Lollar (1994) described the use and fabrication of "roosting caves" she designed for captive Mexican free-tailed bats, Tadarida braziliensis. Pillowcases and "roosting caves" can be fastened easily with Velcro®. Do NOT use tape, hooks or other potentially injurious items to secure roosts. Also, do not use pillowcases with frayed edges, or materials that can snag claws.

Hard-sided cages should be free of branches and twigs, which may injure bats when they stretch their wings. Cages should remain empty with the exception of the types of "furniture" described above: such items protect bats from bright lights and the noise of human activities. Be sure "furniture" is secured to prevent injuries. Injuries also occur when bats roost near the doorjambs of their cages. They become caught between the jamb and the door when the door is closed.

The universal cage (FIG. 28) described below for tree-dwelling and flighty species is also suitable as a flight cage for crevice-dwelling bats. These bats, however, require a roost box with narrowly spaced compartments [e.g., ¾-1½ in. (2-4 cm) apart, depending on species].

Figure 28.  Illustration of an off-display ["universal"] cage suitable for housing a variety of species.  A) cage with interior drape to prevent bats from escaping when the door is opened;  B) roost box.

Tree-dwelling and "Flighty" Bats
Species that normally hang from horizontal surfaces, or vegetation, cannot tolerate the type of confinement required by crevice-dwellers. Although cages for these animals do not have to be enormous, they must be large enough to allow the bats space to flap their wings (static flying), and to get airborne when flipping from one side of the cage to the other. For example, flying foxes kept in cages too small for static flight may lose their ability to fly, or even to extend their wings (Carpenter, 1986). The universal cage design depicted in FIGURE 28 has worked well for a variety of species, including Waterhouse's leaf-nosed bats (Macrotus waterhousii), short-tailed fruit bats (Carollia perspicillata), flying foxes (pteropodids), and all bats in the genus Lasiurus.

This cage design is suitable for bats ranging in size from less than an ounce (e.g., Carollia perspicillata) to about 2 lbs. (e.g., Pteropus vampyrus); albeit, the overall dimensions, mesh size, and roost-box design must vary to accommodate the particular species. Also, some bats (e.g., Carollia spp.) escape when the door is opened. The problem is solved easily by hanging an interior drape across the doorway (FIG. 28).

Depending on its size, this design is functional with or without legs, and it may also be constructed as a walk-in cage (FIG. 29). Frame small cages with 1- by 2-in. stock and large cages with 2- by 4-in. stock. The best type of mesh for siding indoor cages is polyethylene (FIG. 25). This product does not corrode and is easy to clean. Because fruit bats are messy feeders, it is advisable to cover the cage sides with [clear] plastic. Do not, however, cover the top. It is important to allow rising heat to escape from the cage to avoid overheating the occupants.

Figure 29.   Walk-in universal cage.  The frame is 2x4-in. stock (pine).  The floor is 3/4-in. plywood which was later tiled for hygienic reasons.  Newspaper is placed over the tile floor, and it is changed daily.  The mesh-size choice is 1 inch for large flying foxes (Pteropus giganteus).  Polyethylene mesh has been selected over wire mesh because it does not corrode from contact with urine, and it is much easier to clean off fruit pulp which has been spat out by the bats.

Construct a roost box (FIG. 28b) of wood, tack polyethylene mesh tightly to the roof, and groove the sides to provide bats with a relatively irregular surface on which to climb. In addition to variations in cage and mesh sizes, the sizes of the roosting box compartments must also change with the type of bat resident. For example, species that may be expected to fly, not crawl, into the box require adequate space for this behavior.

Coat all wood surfaces with a non-toxic, waterproof substance. It is best to use water-based wood finishes because they do not emit strong odors as do the oil-based finishes. Regardless of the type of finish used, bats should not be placed in a cage until it has cured completely. Water-based paints cure in approximately two or three days. Although the use of non-toxic, oil-based paints are acceptable, they require one month or more to cure.

An alternative roost to a wooden box for flighty species was designed by Willard Wilson (in litt.) for mustached bats (Pteronotus sp.). This species roosts naturally in ceiling domes of limestone caves, and a similar roost can be constructed for them in captivity, to insure their toenails do not overgrow. This structure (FIG. 30) can also be constructed in the top of most cages or exhibits as follows: 

Cut an appropriately sized hole in a 3/4-in. section of plywood (FIG 30a), and attach the plywood to one end of the cage. Fabricate a dome from 1/4-in. hardware cloth or lath (FIGS. 30b, 30e). Apply plaster of Paris to the wire-mesh foundation, and before the mortar dries, embed small aquarium gravel or size 1a limestone particles in the surface (FIG. 30d). Allow the mortar to dry thoroughly, and then seal the surface with two coats of water-based, polyurethane finish.

When housing multiple males with females, unnecessary injuries and deaths can be avoided if several roost boxes or domes, or a combination thereof, are placed in the cage, and spaced as far apart as possible.

An all-mesh cage for tree-dwelling and flighty species maximizes the cage surface for climbing and landing, and the mesh ceiling allows bats to hang on a horizontal surface which is necessary to prevent them from soiling themselves with urine and feces.

Lasiurines may or may not enter roost boxes. They prefer to roost among leaves (FIG. 31). Attach vines or branches at the top of their cages (FIG. 32). Silk leafy vines can be entwined with natural branches to give them a proper surface for preventing overgrown toenails. When using natural products, however, rinse and shake them dry before placing them in a bat's cage.

Figure 31.  Red bats (Lasiurus borealis) roost naturally in trees.  Silk leaves, as shown here, work well as cage "furniture."  Red bats are a solitary species;  however, if a cage is large enough, leaves can provide visual barriers, allowing more than one bat [of the same sex] to occupy a cage (photo courtesy of Amanda Lollar, Minerals Wells, TX).

Figure 32.  A) the proper placement of leaves in a "soft-sided" cage;  B) leaves can be attached to the PVC pipe frame by drilling holes in it - NEVER attach leaves with tape (photos courtesy of Amanda Lollar, Mineral Wells, TX).

Some bats, such as the red bat (Lasiurus borealis), have skin that is easily injured (discussed in Chapter 4). These "delicate" bats may be housed in a small, soft-sided cage (FIG. 33) constructed from any soft, sheer fabric (e.g., 100% polyester or nylon; FIG. 34). Avoid fabrics that block light when housing tree-dwelling species. In contrast, soft fabrics (e.g., Percale® cotton) that provide low light levels are appropriate for species that roost in mines, caves or buildings (e.g., Macrotus spp.). For multi-species use, a sheer fabric can be used, and strategic areas of the cage can be covered with a heavier fabric to satisfy the light preferences of the particular species. This, however, does not mean that multiple species should be housed simultaneously in one cage.   (Click Figure 33 for larger view)

Figure 33.  Instructions for fabricating a soft-sided cage cover (illustration courtesy of Kathleen O. Muller, Carlsbad, CA).

Figure 34.  Because red bats (Lasiurus borealis) live in trees in sunlight, a soft-sided cage should be made with sheer material to allow light to filter into it;  place such a cage under full-spectrum lighting.  A) door zipped closed;  B) door unzipped and pinned open.  To prevent a bat from escaping when the door is unzipped, assemble the cage with the zippers closing at the lower right or left corners (see Figure 35).

For one bat, I recommend a minimum cage size of 24 in. (61 cm) high by 30 in. (76 cm) wide by 18 in. (46 cm) deep. Fabricate a door with two zippers, one running perpendicular to the cage floor and the other parallel. The zipper tabs should meet at either the LOWER right or left corners (FIG. 35). When using newly purchased fabrics for the construction of bat cages, wash out the sizing but do not launder them in aromatic products such as fabric softeners.

Figure 35.  Illustration showing the tabs of the perpendicular & horizontal zippers meeting at the lower right corner of the cage.

*  Cut No. 102 in half with a hacksaw. *  With epoxy ribbon (No. 103), adhere on of the cut sections of No. 102 on No. 101 (at the area of the dotted lines). *  Assemble against a right angle (e.g., where a table meets a wall). Figure 36.  Instructions for constructing a three-way joint assembly for PVC-pipe frames.

Figure 37.  A)  illustration of the PVC-pipe frame used to support a soft-sided cage;  B)  list of materials used in the frame construction (illustration courtesy of Kathleen O. Muller, Carlsbad, CA).

The purpose of the soft-sided cage would be defeated without an appropriate substrate. Cover the cage bottom with sheepskin (FIG. 38). Unlike the natural product, synthetic sheepskin is relatively inexpensive, and enough should be purchased so that one piece can be in use while another piece is being laundered. Use only those with cotton or cotton-like backs to prevent bats from snagging their claws.

Figure 38.  Sheepskin placed on soft-sided cage floors reduces the chance of injuries to delicate bat species such as red bats (Lasiurus borealis).  This material should also be used as a substrate when housing injured, crevice-dwelling species in hard-sided cages.

These cages are not trouble-free. If the cage covers are not changed regularly, urine will rot the fabric. Also, bats housed in these cages may require routine pedicures if they refuse to hang on the branches. Anyone who is unsure about caring for a bat's feet should consult someone expert in foot care of birds or dogs.

Vampire Bats
Although common vampire bats (Desmodus rotundus) may be housed in the universal cage shown in FIGURE 28, the single most important point to keep in mind, with the exception of cage-carrying capacity, is ease of maintenance. Laboratory researchers have housed vampire bats in a variety of cage styles (Dickson and Green, 1970; Schmidt and Greenhall, 1972; Wimsatt and Guerriere, 1961; Wimsatt et al., 1973). The cage-module design in which I housed vampire bats is shown in FIGURE 39. Each module measures approximately 3 ft. (91 cm) high by 3 ft. (91 cm) wide by 2 ft. (61 cm) deep, with a shift/roost box measuring 8 X 8 X 8 in. (20 cm). The shift/roost box serves a twofold purpose: it minimizes the need to handle vampire bats and, when lined with plaster of Paris as discussed above, also provides an abrasive surface necessary for healthy feet. Provide one module per 15-20 vampire bats.

Figure 39.  A)  vampire bat module with roost/shift box;  B) detachable roost box can be cleaned easily, and it can be used to shift animals to another module or shipping crate;  C) when lined with mortar, the roost box prevents overgrown toenails.

The vampire bat modules should open in the front with 1/4-in. polyethylene plastic mesh (FIG. 25) attached to the door frame. Plastic mesh should also be attached with Velcro® to laminated-plastic (e.g., Formica®) cage walls. As previously mentioned, it is preferable to use plastic mesh instead of hardware cloth because it does not corrode and is easier to clean. The only glue I have found suitable for adhering plastic mesh to laminated plastic is a product called Goop™ (FIG. 40). For a cage with the dimensions listed above, the frame can be constructed with 1-in. by 2-in. stock.

Figure 40.  Plumbers Goop™ is satisfactory for attaching Velcro® to both laminated plastic surfaces & polyethylene plastic mesh, products used in the construction of vampire bat cage modules.

When housed properly, a colony of Desmodus breeds prolifically, and a cage can become overcrowded quickly. At the first sign of injury to females or juveniles, suspect overcrowding. As each module reaches capacity, add another. As shown in FIGURE 41, a total of 4 modules can be attached together. The square configuration provides a circular flow of traffic, allowing subdominant animals to return to their own roost without becoming trapped and injured by dominant bats: avoid attaching modules together in a straight line, as such a configuration can lead to fatalities.

Figure 41.  As a vampire bat colony grows in size, it can be kept intact by joining cage modules together with 4-in. PVC pipe.  Up to 4 modules can be attached when using a square configuration.  With the exception of the first two modules, NEVER attach them in a straight line because such a configuration can lead to fatalities.  The square configuration provides a circular flow of traffic, allowing subdominant animals to return to their own roosts without becoming trapped and injured by dominant bats.  Any one or all of the modules can be closed off by reaching inside the cage and screwing on the pipe cap(s).  While workers perform this task, the bats will usually stay in their roosts.

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