While the Mauritius fruit bat is in the limelight of research and conservation actions, the other group of bats- the insectivorous ones are neglected and overlooked. ERA IO is the only NGO in Mauritius that actively works with all the Mauritian bat species. Small and less conspicuous than their fruit bat relatives, insectivorous bats are the unseen heroes of the dark.
Insectivorous bats are special- they are not blind but rather use echolocation (cool dolphin language) to navigate and find food and the dark.Talking about food, the main component of insectivorous bats’ diet is insects. One single bat can eat between 6,000 to 8,000 insects each night! Most insects eaten by these bats are pest of commercial crops such as sugarcane, litchi, potatoes and many more. This crop pest suppression is probably the most valuable ecosystem service provided by our insectivorous bats. They act as ‘natural insecticides’ and also protect human health by eating pathogen-carrying insect vectors. Our insectivorous bats thus control of spread of diseases such as Malaria, Chikungunya and Dengue. Two insectivorous bats are found in Mauritius, namely the Mauritius free-tailed bats (Mormopterus acetabulosus) and the Mauritius tomb bats (Taphozous mauritianus).
1. Cave Bats
The Mauritius free-tailed bats (Mormopterus acetabulosus) is the only endemic insectivorous bat in Mauritius. The species is an exclusive cave-dweller, leaving the caves only at night for foraging. Like majority of bat species around the world, M. acetabulosus gives birth to one baby per year, which makes the species highly vulnerable to extinction. Indeed, the Mauritius free-tailed bat is currently listed as Endangered on the IUCN Red List. The species can also play an important role in cave ecosystems by providing guano, which is often the only allochthonous nutrient supply in this type of environment. These caves also provide habitats for invertebrate fauna, most of which have not yet been documented. However, our recent surveys showed a drastic 80 % reduction in the population of cave bats and surveys of some major roosts suggest that human activities are problematic. Intensive rubbish dumping, cave entrance closure, cave vandalism and chemical pesticide overuse are potential threats besetting the survival of the Mauritius free-tailed bats. In collaboration with the University of Mauritius, we are doing a long-term research study to elucidate the reasons of decline of this endemic insectivorous bat and thus inform proper management actions to conserve the species.
2. Tomb Bats
The Mauritius Tomb Bat (Taphozous mauritianus) is an insectivorous bat native to Mauritius. The species is also found in central and southern mainland Africa and Madagascar. The Tomb bat is characterized by an all-white ventral surface, greying dorsal colouration and a conical face. The species can be seen resting on the trunks of palm trees, coconut palms and also on the surface of buildings during the day. In general, they choose their daytime resting places so that take-off is not hampered by obstacles preventing their flight. Little is known about this insectivorous bat species in Mauritius. Even though the Mauritius Tomb bat is listed as ‘Least Concern’ on the IUCN Red List, the species is rapidly disappearing from Mauritius and this for unknown reasons. Loss of habitat and excessive pesticides use that reduces the prey availability to the Mauritius Tomb bat are potential reasons of the decline.