Born for the Night Shift
As our group entered the cave-like area from bright summer sunlight, I stumbled slightly, allowing my eyes to adjust to the dimming light. Without any prompting, our laughter dissolved into cautious whispers. The glass panel we faced was slightly obscured by condensation—on our side, a cool summer breeze, on the other, a moist tropical atmosphere. There they were, hanging upside down, like furry brown birds in long trench coats, nibbling on pieces of nectarine and mango: my first glimpse of Rodrigues Fruit Bats, up close and personal. I was mesmerized. No, enraptured.
It was like peering into another universe. Our group watched in silence as the bats walked upside down on the wire-mesh ceiling, foraged for fruit, chased one another, squabbled, and then rested together. More secluded spaces housed mother bats, nursing their single offspring upside down, pups clinging to their mothers’ armpits. It was a topsy-turvy universe, disorienting but exhilarating, and easily the most memorable part of my visit to the African rainforest habitat in Portland’s Oregon Zoo.
Until that moment, I hadn’t thought much about bats. They are night dwellers, invisible, secretive, and maybe a little scary. I’d seen them before in caves, high up and hanging by the merest foothold along some rocky crevice. As a daytime dweller, birds, not bats, defined my encounters with nature. That all changed after meeting the Rodrigues bats on a warm summer day, so you can imagine how thrilled I was to learn that a colony of fruit bats would be coming to Tucson as part of the Reid Park Zoo expansion, The Pathway to Asia.
Wildlife professionals who work on behalf of these amazing animals will tell you that bats are under-appreciated and greatly misunderstood. Let’s get right down to basic bat facts.
There are so many bats! We may rarely see them, but there are more than 1,400 species of bats living in nearly every part of the world, except for the harshest desert and polar regions. These small mammals range in size from the Bumblebee bat, which weighs less than a penny, to the largest fruit bats, which have wingspans of up to 5 ½ feet.
Humans rely heavily on birds, bats, and other animals to help keep our planet livable, some would say survivable. With birds working during the daylight hours and bats working the nightshift, nature provides us with round the clock pest control. Some scientists believe that bats’ preference for the night shift evolved as a way to avoid predation, mainly from birds, and has enabled them to share the same food source without confrontation or competition. Although all bats eats insects, and many do so exclusively, some have evolved to become fruit and nectar specialists providing another important ecological service—pollination!
Bats can be divided into two primary groups, Microbats and Megabats. As their names imply, Microbats have smaller bodies but larger ears which help them use their superpower, echolocation, a useful adaptation which helps them find food in the dark (insects) and avoid obstacles in the process. Micros are primarily insectivores, and their role is pest control. At the other end of the spectrum, Megabats have larger bodies, larger eyes with keen vision, and a great sense of smell. These sensory superpowers help them find their food (fruits and flowers). Megas have evolved as frugivores and nectarivores, and their role is pollination. Depending on where they live and their ecological role, bats can thrive in caves, rock shelters, and high-altitude mountainous ranges, but they also thrive in tropical forests, roost in trees, and one species even burrows in the ground (for all you bat fans, the North Island of New Zealand). In urban areas, they find man-made crevices to call home: attics, eaves, barns, industrial-sized buildings, tunnels, and bridges. Bats can live solitary or social lives. Some prefer to live alone or in pairs, some in small- to medium-sized harem groups (a dominant male with many females and a few immature males close by), and some in small to massive colonies.
How massive? Bracken Cave, near San Antonio, Texas, is home to about 20 million Mexican Free-Tailed Bats who roost there, giving birth and raising pups, from March to September. This is the largest known bat colony in the world, although this number may not be entirely accurate because bats are difficult to count. 500 babies can huddle to keep warm by hanging onto one square foot of rock ceiling. How’s that for efficient use of space? The Bracken Cave colony is well-protected by Bat Conservation International, an international, non-governmental agency, and The Nature Conservancy. The city of San Antonio also enforces no-development and dark-sky regulations to protect their cave and the land surrounding it.
Bats in the desert
Moving west, Arizona has the second largest number of bat species (28) in the U.S. , second only to Texas. The Mexican Free-tailed Bats of Bracken Cave fame are common in Tucson and have found handy urban homes under large bridges over the Pantano Wash and the Rillito and Santa Cruz Rivers. You can observe them—from a polite distance, please—flying out from underneath their bridge-caves at dusk . They mingle with other local bat species and share the ecological work; some are insectivores while others work as nectarivores.
While many Tucson residents may look forward to celebrating National Tequila Day , aka Thank A Bat Day, on July 24, I will be celebrating the birth of bat pups in Kartchner Cavern’s Big Room. This chamber is home to a small colony of myotis velifer, or the common cave bat.
Every year on April 15, Kartchner staff close all the doors to the Big Room, turn off all the lights, and do not enter the cave again until late September, well after the bats have migrated away to hibernate for the winter. During the summer months, the bats are busy giving birth, raising pups, and teaching them how to fly, echolocate, and hunt for their food. You may visit the Rotunda and Throne rooms during the summer, but, in the Big Room, it’s all about baby bats. Like the rangers at Kartchner, we should feel good about honoring the privacy of this very special colony as it perpetuates a life cycle perfected by more than 50 million years of evolution.
Two other bats common to the Arizona and Mexico region are the Lesser Long-nosed Bats and Mexican Long-tongued Bats . As their facial characteristics feature prominently in their names, can you guess what they eat? Both are nectar feeders and pollinators! They literally bathe themselves in pollen while searching for the fruits of agaves, saguaros, and organ pipe cacti. Like most animals, they are highly opportunistic and will also visit not-quite-depleted hummingbird feeders after those tiny birds have gone to roost. (Now you know why your nectar disappears overnight.)
It’s worth mentioning the monetary impact of bat populations; some people can relate more to dollars than wings, feathers, or fins. (Not judging! We all need their expertise and their support, too.) The U.S. Geological Survey estimates that, by eating insects, bats save U.S. agriculture billions of dollars per year in pest control. Some studies have estimated that service to be worth over $3.7 billion per year, and possibly as much as $53 billion, but this does not include the volume of insects eaten by bats in forest ecosystems, which benefits the lumber, paper, and other forest industries, or the bats’ service as pollinators. My calculator says the actual monetary worth of bats is far greater than $3.7 billion per year. Incalculable? Maybe. But that’s another story.
Bats in the tropics
Traveling much farther west around the globe and sailing south into the Indian Ocean, we can find my favorite bat, the Rodrigues Fruit Bat, or flying fox, a common name for larger fruit bat species in the world. The Rods, as they are affectionately known, are considered endangered (by the International Union for Conservation of Nature (IUCN). In the wild, they only exist on the tiny island of Rodrigues located about 900 miles east of Madagascar off the eastern coast of Africa. They live in dense tropical rainforests filled with large, mature trees (emphasis on mature, not young).
In the 1970s, as the Rodrigues rainforests were cut and their habitat destroyed, the Rod colonies were pushed further and further to the edge of their 42 square mile island until they occupied just a small, wooded valley—barely enough room to survive. Unlike some of their desert counterparts, Rodrigues bats are frugivores and use their keen eyesight and sense of smell to find ripening mangoes, figs, and other fruits. The extraordinary thing is that they crush their food, swallow only the juices, and spit out the pulp and seeds in a pellet shape, creating a ready-made seed-packet. They live simply to regrow the rainforests.
Unfortunately, they haven’t been able to regrow the forests fast enough. After a cyclone hit the island in 1979, the Rods were down to less than 70 individuals; they had become the rarest bats on Earth. Emergency conservation efforts led by English naturalist George Durrell brought them back from the brink of extinction. Individuals from Durrell’s first translocated colony are now being raised and cared for by about 15 accredited institutions worldwide, including the Oregon Zoo, the San Diego Zoo Safari Park, the Chester Zoo in northwest England—home to the largest Rodrigues colony in the world and holder of the Rod bat stud book—and soon, the Reid Park Zoo in Tucson!
More bats coming to Tucson
In the Reid Park Zoo’s Pathway to Asia expansion, guests will have the opportunity to observe these amazing animals and learn how they, along with our own desert species, contribute to the health of our planet. As a bat fan, I want you to hear this bat’s story and understand the role they play in the web of life. Most importantly, I want you to care.
When I contemplate the fate our natural world, pretty much an everyday occurrence in 2021, I find inspiration in the words of my wildlife heroes, Jane Goodall and Jacques Cousteau , about Why We Should Care. Both individuals dedicated their lives to conservation of the natural world by raising our awareness and demonstrating how each one of us is connected to the web of life. Goodall said, “Only if we understand, will we care. Only if we care, will we help. Only if we help, shall all be saved.” Cousteau may have said it more simply but with no less conviction, “People only protect what they love.”
I’m proud to say that in our little corner of the desert southwest, our small but mighty Reid Park Zoo will become one of a select few chosen to help maintain a genetically diverse population of Rodrigues Fruit Bats and, through human care, research, and financial support, prevent their extinction in the wild. When this new habitat opens, I hope that your first encounter with these small furry creatures, living their topsy-turvy lives on the perpetual night shift, fills you with a sense of wonder and excitement and inspires you to support their conservation. I hope you, too, will experience love at first sight.