Last Monday saw a revival of interest in bats around Halloween. A fact sheet from the International Union for Conservation of Species was put out for the occasion. According to the IUCN Red List of Threatened Species, around 20 per cent of all bat species are now threatened.
Bats carry out important ecological services: pollination, seed dispersal and reduction of pest insects- Anne Zammit
Co-chairman of IUCN’s species survival commission Paul Racey stressed the need for better bat conservation and educating people to value the world’s only winged mammals.
“Bats are disappearing at an alarming rate, due largely in part to ignorance and a misunderstanding of the benefits they provide,” commented the bat specialist last week.
Bats, of which there are around 1,250 different species worldwide, come from an ancient family of mammals and are unique in having forelimbs which developed into webbed wings.
Portrayed as spooky creatures mainly due to their silent, nocturnal flight, bats are crucial to the environment. They carry out important ecological services: pollination, seed dispersal and reduction of pest insects.
The largest bat in the world is probably the ‘flying fox’ with a 1.5- metre wingspan, found across much of Asia. These bats use vision rather than echo-location for navigation and find food using their acute senses of sight and smell.
The smallest bat on the planet is the hog-nosed or ‘bumblebee’ bat restricted to Thailand and Burma. At only about 30mm long, it is probably the smallest species of mammal in existence and can hover as well as dart to catch its prey.
Generally, bats have one single offspring, and a female giving birth to twins is a rare event. A young bat is called a ‘pup’, and groups, referred to as colonies, are sometimes called a cloud when in flight, as they would seem to darken the sky emerging from their roosts at sunset.
Some bats fly in daylight but this makes them more vulnerable to predators. Agricultural chemicals and habitat loss are usually the main cause of dwindling bat populations.
Their ultrasonic prey detection and obstacle avoidance system is sophisticated, and attempts have been made to replicate it to produce aids for visually-impaired people.
Eurobats, the European Bat Agreement of 1994, aims to protect all 52 species of bats identified in Europe. The list includes the Egyptian fruit bat, long fingered bat, whiskered bat and the European free-tailed bat, an unusual visitor first seen in Malta in 1993.
These islands have provided habitat to 11 species of bats in all. Six of them are resident while the other five species are considered to be rare and irregular migrants.
The Maghreb bat is the largest found locally. In 2007 a Maghreb bat roost in Gozo was discovered in underground World War II shelters. At the beginning of the century they were very common in Malta, with large numbers seen leaving their roosting caves on summer evenings.
A bat cave in the south of the island, Għar il-Friefet, was abandoned after works disturbed the resident bats. Every time a truck went by, the bats would take alarm and fly out. Finally they deserted the cave that had been their home for many generations.
The common pipistrelle was split into two different species in 1999 when echo-location was recorded among seemingly similar bats at two different frequency ranges. The bats, which were found to be sounding at a higher frequency, were then renamed soprano pipistrelles.
Since the two species have been distinguished, a number of other differences, in appearance, habitat and food have also been discovered. There are 33 types of pipistrelle around the world, four of which can be found in Malta.
Soprano pipistrelles, also known as pygmy bats, feel at home in rural areas, small villages or large towns. They are especially fond of urban gardens with insect-attracting bushes and can roost in wells if left undisturbed. They can be seen swooping and feeding around white street lamps or floodlights.
A rarer type of pipistrelle bat, only recently recorded in parts of Malta, appears to be in decline since it roosts in walls, making it subject to disturbance from restoration projects.
The Malta Environment and Planning Authority has been issuing permits for trapping and handling of bat species for conservation purposes since 2005.
Collection of population data and DNA studies have been carried out in Malta on the Maghreb and lesser horseshoe bat, the latter named for the shape of its nose.
The ‘horseshoe’ acts as an acoustic lens, focusing the echolocation sound waves emitted from the nose. During winter they may also remain dormant in caves. Its larger cousin, the greater horseshoe bat, is thought to be extinct in Malta since it has not been seen for over 20 years.
Wied il-Lunzjata in Gozo provides the type of habitat favoured by the endangered grey long-eared bat which lives in wooded areas and valleys with running water.
Buskett and Girgenti are also suitable for this bat, which can take a liking to fields and open reservoirs. At the last count they were estimated to be only 150 to 200 individuals and their numbers were decreasing due to disturbance.
Some of the Maghreb bats that were caught, ringed and released in Malta turned up in Gozo. All the same, it is unlikely that a diminishing local population could be replenished by other colonies flying over from North Africa or other islands.
Ocurring only in the Maghreb states and three Mediterranean islands (Corsica, Sardinia and Malta), the Maghreb bat is listed by IUCN as “data deficient”. Between the mid-1980s and early 90s the Maltese population of these bats dwindled to half. By 2002 the colony was reported to have stabilised at 400 to 450 individuals. But the latest news is not good.
Bat grills were installed in at least two well known bat caves to prevent disturbance, but these admirable and private initiatives have not been enough on their own.
A bat enthusiast who visited Malta last spring to study bat fauna wrote about the particularly Maltese problem of hunters using bats for target practice as they fly out of their roosting places.
“When I was there, the sound of gunfire was a constant backdrop, away from the towns,” writes David Dodds on his bat blog. Mr Dodds recalls how he visited two of the biggest colonies of Maghreb bats in southern Malta, “…neither of which showed any signs of being used by the species any longer”.
In a recent update, senior curator of natural history at Heritage Malta and head of the Malta Bat Group John Borg confirms:
“Bats in Malta have been on the decline since the 1980s, especially the larger species like the Maghreb Bat (Myotis punicus) whose population has dropped by more than 70 per cent.
“Traditional colonies such as the aptly named Għar il-Friefet at Birżebbuġa and Għar Ħasan at Ħal-Far became deserted. The bat grill at Għar Ħasan has been vandalised several times, including in recent months.”
Unfortunately, the news from Gozo is not too good either:
“Another important site for this species, Għar Siekel, close to Lunzjata Valley in Gozo has been taken over and a steel door has been fitted at the entrance, impeding free passage to the bats.”
On the other hand, adds Mr Borg, some of the populations of the smaller species, such as the four pipistrelle species appear to be stable with a high level of activity registered this autumn.
In spite of regular educational activities carried out at the National Museum of Natural History, bats are still threatened:
“In some areas such as Lunzjata Valley in Gozo and around Girgenti Valley in Malta some irresponsible hunters still shoot at bats, especially pipistrelles, which are early risers.”
Another issue related to the conservation of bats, explains Mr Borg, is the amount of restoration projects carried out on the bastions, chapels and other buildings.
“As no environment assessment is carried out, several bat roosts have been blocked.” The bats are sometimes left to perish inside.
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