Bats have a unique claim to the islands of Fiji: theyre the only native mammals of the island group. The archipelago of 333 islands is home to only six species of bat, five of which are endangered or threatened.
While three of those bat species are considered megabats, or bats that dont echolocate, the Fijian blossom bat is unique in that it roosts in caves. These roosts are usually found in the darkest areas of large, high-ceilinged cave structures.
This species is also known as the long-tailed fruit bat, and its easy to see whya long, mouse-like tail hangs freely from its rump, unconfined by any tail membrane. Unlike the other two species of megabats found in Fiji, which weigh an average of about 500 grams, blossom bats are small, weighing between 5060 grams and have an average body length of only 4 inches from snout to rump. As for the flower moniker, some bat specimens have been captured in close proximity to blossoms, on which the bat is believed to feed.
Though the Fijian blossom bat also has been seen on the island of Vanuatu, only five colonies are known, all of them on Viti Levu, Fiji, and most of them in close proximity to human population centers. Little direct research has been done on the species, and most of the natural history of this animal comes as a result of periodic surveys conducted in Fijis caves and forested mountain zones.
Joanne Malotaux, a Dutch instructor of biology, spent six months conducting such surveys in Fiji while working with the nonprofit conservation group NatureFiji-MareqetiViti. While she was visiting the village of Nabukelevu with Kelera Macedru, Conservation Officer for NatureFiji-MareqetiViti, to talk with villagers there about bat conservation, a hunter told the pair about a nearby cave with many bats. With no previous documentation of any such bat cave in the area, Malotaux and Macedru were eager to organize a field trip to check it out.
We found a massive cave with a colony of thousands and thousands of the Fijian blossom bat, Malotaux says. It doubled the known population of the species in Fiji. Far from human habitation, the cave is relatively undisturbedone possible reason for the thriving population that roosts there.
The remaining sites on the island where the blossom bat lives are threatened, in one way or another, by the presence of humans. A large limestone quarry is situated next to one of the caves, and two others have become tourist attractions. Locals use the caves as trash dumps in some areas. At other caves, local harvesting of bats, between 100 and 500 per year, has reportedly stopped, but exact counts of bats in their roosts are difficult to conduct due to the presence of white-rumped swiftlets (Aerodramus spodiopygius) that occur alongside the blossom bats in the caves. And because the bats are sensitive to bright light, theyre easily disturbed by tourist groups bearing flashlights.
Some of Malotauxs work with NatureFiji-MareqetiViti involved speaking with locals about the benefits and advantages of having bats nearby, for example, how they help pollinate wild and domesticated crop plants.
But much more information about the bat is needed to accomplish the outreach mission. Though its known that the bats will make their way into the highlands from their lowland caves, the specific plants on which they forage are relatively unknown. Their cranial structure and long tongues are well-adapted for foraging pollen and nectar, which is supported by the few dietary studies that have been carried out on this species. While the full list of forage plants for this species is still unknown, there is evidence that blossom bats rely on plants such as Barringtonia seaturae, a Fiji endemic tree, and plants in the genus Syzygium.
The bats do have an important ecological role to play, Malotaux adds, but little is known about their feeding preferences.
The species may be a good target to advance the cave conservation work already underway in Fiji.
Jason Corbett, Director of BCIs Subterranean Program, will be conducting new assessments of the blossom bat roosts later in 2018, along with partners from NatureFiji-MareqetiViti. The ability to preserve the last remaining maternity roosts of this threatened endemic species may be their lifeline into the future.