African Bat Biodiversity Project.
In October of 2008, a NGS/Waitt grant enabled Michael Curran and his team to join a Darwin Initiative expedition to two isolated mountains in northern Mozambique. They were part of a large team of researchers whose aim was to explore the biological diversity and conservation importance of these mountains.
Rising out of relatively featureless plains like islands in the sea, these mountains have evolved complex, yet fragile ecosystems where a bewildering number of plant and animal species coexist. The team surveyed the bat communities of these mountains and assessed their biological importance. Historically, very little research has been conducted on the Afromontane bat communities due to the inaccessibility of mountainous areas.
The team’s research in 2007 included an investigation of diversity patterns of bats on the magnificent Mount Mulanje, in southern Malawi, the country’s only UNESCO Biosphere Reserve. The findings from this research gave them an indication of the importance of Afromontane ecosystems to threatened and forest-restricted bat species. Since then they have been working to discover more about these fascinating ecosystems and the bats that rely on them for survival. The expanses of evergreen (“Afromontane”) forest are particularly threatened by growing human populations driving unsustainable exploitation. As the forests and other important ecosystems dwindle across Africa under increasing human pressures, basic research is needed to document and understand what would be lost, before it is too late.
Using a standardized methodology that includes the use of mist nets, canopy nets, harp traps and acoustic monitoring (recording ultrasonic bat calls using a bat detector), Curran discovered that these Afromontane forests support a very large proportion of the region’s bat diversity within a very small geographic area. Visiting eight sites across three mountains in Mozambique and Malawi, they captured 245 bats representing about 27 species.
This includes two new records for Mozambique that add to the countries burgeoning species list, the long-eared bat, Laephotis botswanae, and a forest-restricted woolly bat, Kerivoula sp. The team also discovered a horseshoe bat that represents a completely new scientific species. This species appears to be an Afromontane endemic, recorded within the montane forest of a single mountain.
The expedition also conducted the first survey of the isolated Mount Mabu, which contains the most expansive and intact area of montane rain forest known in southern Africa. Discovered only in 2003, Mount Mabu testifies to how little is known about the planet and the biodiversity it contains.
Panama's Adaptable Bats.
Sixty million years ago, on a planet crawling with mammals, one tree dweller rose above the crowd on paper-thin wings. So goes the story of ancestral bats, which, equipped with flight and a sixth sense called echolocation, mastered the night sky and flourished.
Having since exploded into more than 1,100 species worldwide, bats are still finding unique ways to evade the masses—and each other. Barro Colorado Island, a Key West–size knob of land in the Panama Canal, is a showplace of bat innovation. This patch of tropical forest is home to at least 74 distinct bat species; the entire United States has only 47, and all of Amazonia, with perhaps the highest bat diversity on Earth, logs about 160. With many thousands of individual bats sharing the island's 3,800 acres (1,500 hectares), it's a wonder their jagged wings don't entangle as they struggle to meet life's basic needs.
How do they all live in peace, skirting competition that would drive some to extinction? By finding their own niches in the forest's many layers. Where they roost, what they eat, when they feed, how they use their senses, where in the forest canopy they fly—each species has its own special how-to list inscribed on its genes, its own ways to exploit the island's endless summer. One bites through the lateral veins of a leaf to fold the sides down—creating a tentlike shelter for up to 15 of its kind to share. Another chews out a home for its harem in the heart of a termite nest, prompting the insects to move over and make room. (These bats choose only occupied nests as roosts; scientists are trying to find out why.) Some species chase down insects in the air, while others lick nectar and pollen from night-blooming flowers. Some use short pulses of sonar-like echolocation to find perched insects amid forest clutter; others send out longer calls to pinpoint airborne bugs, staying high above the tangled canopy.
Physical differences reflect these distinctive habits. Take greater bulldog bats, with their dagger-like claws and cheek pouches, in which they can carry fish they don't eat on the wing. Or herbivorous bats, some equipped with bristled tongues and grooved chins to pick up nectar and pollen as they nuzzle blossoms. Long, thin wings suit the bat that soars on high; broad, compact wings allow quick turns for the one dodging trees down low. Ample ears? Tiny eyes? Flesh-ripping canines? A nose flap? Each feature is a clue to how a species makes its living.
The tropical forest not only supports this immense diversity, it also depends on it. Bats spread seeds and pollen, keep a cap on herbivorous pests that might decimate forest flora, and themselves become meals for other forest animals—monkeys, owls, falcons, other bats, even large spiders. Such a healthy ecosystem can sustain quite a crowd, especially when each species knows its place.
Common Vampire Bat.
Bats are the only mammals that can fly, but vampire bats have an even more interesting distinction—they are the only mammals that feed entirely on blood.
These notorious bats sleep during the day in total darkness, suspended upside down from the roofs of caves. They typically gather in colonies of about 100 animals, but sometimes live in groups of 1,000 or more. In one year, a 100-bat colony can drink the blood of 25 cows.
During the darkest part of the night, common vampire bats emerge to hunt. Sleeping cattle and horses are their usual victims, but they have been known to feed on people as well. The bats drink their victim's blood for about 30 minutes. They don't remove enough blood to harm their host, but their bites can cause nasty infections and disease.
Vampire bats strike their victims from the ground. They land near their prey and approach it on all fours. The bats have few teeth because of their liquid diet, but those they have are razor sharp. Each bat has a heat sensor on its nose that points it toward a spot where warm blood is flowing just beneath its victim's skin. After putting the bite on an animal, the vampire bat laps up the flowing blood with its tongue. Its saliva prevents the blood from clotting.
Young vampire bats feed not on blood but on milk. They cling tightly to their mothers, even in flight, and consume nothing but her milk for about three months.
The common vampire bat is found in the tropics of Mexico, Central America, and South America.
Ozark Big-Eared Bat.
The Ozark big-eared bat is an endangered species found only in a small number of caves in the southern central United States. Also known as the western big-eared bat, the long-eared bat, and the lump-nosed bat, its appearance is defined by a pair of outsize ears and a lump-adorned nose.
These bats, whose bodies are normally less than 4 inches (10 centimeters) long, have ears that extend more than an inch (2.5 centimeters) in length. Their ears are generally held erect, except during hibernation, when some bats coil them like ram’s horns.
Beyond the mythical ears, these bats have two distinctive facial glands on either side of their nose resembling a pair of mittens. Their fur is light to dark brown, and their bellies are tan. They have a sizeable wingspan as well, measuring some 12 to 13 inches (30 to 34 centimeters).
The Ozark big-eared bat feeds primarily on moths but may also eat other bugs in and around its forested hunting grounds. It makes its home in caves, relying on their protection during hibernation and maternity.
Mating among these bats is initiated with ritualized calls and affectionate head nuzzling. The female stores the male’s sperm until spring, when ovulation, fertilization, and gestation occur. A single baby, or pup, is born in May or June, already weighing one-fourth of an adult's body weight. Baby bats mature quickly becoming fully independent and able to fly within two months.
The Ozark big-eared bat once lived in caves in Missouri, Arkansas, and Oklahoma. However, they have apparently abandoned their Missouri habitat due to human encroachment and cave disturbance, and estimates put the remaining wild population at around 1,800. Conservationists are currently working to protect these numbers by minimizing human intrusions.