By Dennis Pate
When we decided to build a large bat exhibit as part of a larger African rain forest project, I worried quite a bit about whether it would "work" or not. Would the bats be active? Would they fly? Would zoo visitors be able to see them as they really are, or would it confirm their childhood nightmares?
As a keeper many years ago, I had responsibility for a small bat exhibit, and as I cleaned it, I often daydreamed about what would make a truly great exhibit. In 1990, as general curator at the Metro Washington Park Zoo in Portland, Oregon, I finally had the chance to try out some new ideas with my colleagues.
I had visited many zoos over the years, seen their bat exhibits, and added bits of all of them to my memory. Very few were built from the start to be bat exhibits. Most were generic, box-like, faux-cave displays in the nocturnal house, which seemed to serve the bats well, but did little for their image. Typically, the bats roosted in the darkest, farthest corner of the space, and were noticed by only the most dedicated visitors.
One of the main reasons our design in Portland works is because it allows the bats to be active. The ceiling is constructed of one-inch wire mesh and functions much like the intricate filigree of a natural tree canopy. It provides 1,000 square feet of roosting space and allows the bats to climb across the canopy ceiling. It also encourages more flight due to the ease of landing. The exhibit is horseshoe-shaped, so visitors can stand in the middle and watch bats fly around them. The horseshoe is 12 feet wide at the center and 14 feet wide at the ends, allowing flying bats more room to turn. They can also dip into the 1-inch-deep pool, skimming the surface to drink in flight.
All of this is set against a beautiful mural of a forested valley at sunset. We wanted visitors to be able to view the roosting bats against a simple, light background, and we achieved this by painting distant hazy mountains. Orange and yellow spotlights enhance the sunset sky, illuminate the bats around feeding areas (hanging fruit kabobs), and provide some spot heat for bats to bask in close to the viewing windows. Over 100 feet of artificial but natural-looking vines add to the forest setting and create highways to feeding sites and alternate roosting areas. The dark floor of the exhibit is 30 inches below the visitor level, further adding to the feeling of looking out over a valley while providing plenty of flight space for the bats.
The exhibit currently houses four species of fruit bats: 33 straw-colored bats (Eidolon helvum), 24 Rodriguez fruit bats (Pteropus rodricensis), 20 Egyptian fruit bats (Rousettus aeqyptiacus), and 15 Jamaican fruit bats (Artibeus jamaicensis). The straw-colored bats are the most dynamic species in the exhibit and are active early in the day and in the afternoon. They roost as a loose-knit group in the center of the exhibit and are popular with zoo visitors because of their varied behavior and beautiful gold-colored backs. They feed, breed, bicker, groom, tend their young, and, on occasion, attempt to "mug" one another if the opportunity presents itself and the reward is great enough (usually a cube of fruit). These behaviors seldom result in any injuries.
Some of the less dominant Rodriguez fruit bats sometimes land on the floor to pick up dropped fruit. To help them return to the ceiling roosting areas we have hung nearly invisible ladders of black plastic netting at each end of the exhibit and along the back of an artificial tree.
Seeing the exhibit work for the bats is one thing; watching how visitors react is quite another. What we most often witness is children "taking their parents to school." Adults usually react first with the standard "Yuck! Bats!" This only encourages the children to continue, insisting their party move up for a closer look. In no time, everyone is watching the bats carry on, sometimes at eye level, often within one or two feet of the visitors.
Our straw-colored bats have done extremely well, doubling their colony size since 1990. The Rodriguez fruit bats are also doing well, with each of the eight females giving birth and raising young. The Jamaican and Egyptian fruit bats are all males and work well with the larger bats. Over time, these two species will be replaced by Rodriguez and straw-colored bats and perhaps another species in need of space. We are just completing a research project to document behaviors among the bats, with the goal of encouraging other zoos to try something similar and thereby create much-needed additional space for endangered bats.
Dennis Pate is the general curator at the Metro Washington Park Zoo. He serves on the Bat TAG and is the species coordinator for the straw-colored bat.