SOS: Bats Gone Missing!

Eco Hvar is not alone in being worried that bats are increasingly rare on Hvar Island.

Pipistrellus nathusii Pipistrellus nathusii Croatian Natural History Museum / Hrvatski prirodoslovni muzej

Once, not so long ago, they were plentiful. During the balmy summer evenings they would stream around any source of light, big or small, in the hunt for insects to feed on. I remember them milling purposefully around from my earliest days in Pitve over 25 years ago. In September 1993 there was one sleeping peacefully hanging from a beam in the wine-cellar. A friend remarked that having a bat on one's premises brought good luck to the house. This optimistic belief is not unique to Dalmatia. In traditional Chinese culture bats represent good fortune and blessings.

Colony, pipistrelli kuhlii. Photo courtesy of the Croatian Natural History Museum

In the last few years, bats have been less and less visible. In Pitve in 2016 I saw no more than a handful, and people in other places around the island have also reported seeing very few, if any bats, where once they were numerous.

Bats belong to the order Chiroptera, and are the only mammals capable of flying. There are over 1100 different types of bat in the world, making them the second largest group of mammals, after rodents. In Croatia there are 35 types, belonging to eleven families. Most of them feed on insects, while one, the rare giant noctule bat (Nyctalus lasiopterus) sometimes also catches smaller birds, while the long-fingered bat (Myotis capaccinii) can catch small fish.

Nyctalus noctula. Photo courtesy of the Croatian Natural History Museum

In Croatia Dr. Igor Pavlinić, Custodian of the Croatian Natural History Museum in Zagreb, has been involved in the study and protection of bats for many years. He is conducting a long-term project monitoring a colony of bats at Šćuza, including proposals for their protection. He has demonstrated how bats not only make their homes in woodlands, but also in the most diverse of places, from caverns, caves, abandoned mines and gaps in stones (mostly for winter hibernation), to loft spaces in houses and churches, chimneys, as well as spaces in the walls of bridges. Several colonies on Hvar bore this out. For example, over many years European free-tailed bats (Tadarida teniotis) nested in the belfry of the Church of Our Lady of Health above Jelsa. Sadly, following lengthy renovation works in the past few years, the bats disappeared and never returned.

Our Lady of Health, Jelsa, once a haven for bats. Photo Mirko Crnčević

Bats are said to be an 'index of health' in any given place. They do a good job, actually an essential service for human comfort. One bat can devour between 500 and 1,000 mosquitoes per hour; in the course if a night, it can consume prey equalling about one third of its body mass. Is it a coincidence that as bat numbers have fallen over the last few years, mosquitoes have become more and more of a problem, despite ever-fiercer desperate attempts to eradicate them with chemical poison sprays?

Bats are among the oldest surviving mammals, whose development probably began at the time when dinosaurs dominated the world. The evolution of bats gives rise to some of the most intriguing questions within the history of the evolution of today's mammals. The only thing the majority of scientists agree on is that the bat's early ancestor was a type of nocturnal insect-eating mammal which lived in trees. The latest molecular research has shown that the ape (homininoidea) arose in a later development from a common ancestor, providing a link to humans.

Eptesicus serotinus. Photo courtesy of the Croatian Natural History Museum

Eptesicus serotinus. Photo courtesy of the Croatian Natural History Museum

The decline of bats on Hvar is, sadly, not unique. Bats are under threat around the globe, some types are close to extinction. The Croatian State Institute for Nature Protection identifies several factors as potential causes of bat decline (brochure in Croatian):

1. LOSS OF HABITAT, including excessive felling of old established trees; adapting caves as tourist attractions; flooding of caves; renovation of old buildings without due care for bats' needs

2. LOSS OF NATURAL HUNTING GROUNDS

3. POISONOUS CHEMICAL TREATMENTS OF WOODEN RAFTERS

4. PESTICIDE USE

5. REDUCTION OF INSECTS (often through use of insecticides, and industrial-scale agriculture)

6. TOURISM IN CAVES

7. DISRUPTION TO NESTS AND WINTER COLONIES

8. WINDFARMS

9. DRYING UP OF SURFACE WATERS

10. POLLUTION OF WATER SOURCES

A monograph by I. Pavlinić published by the Natural History-Mathematics Faculty at the University of Zagreb places the blame for the bat decline squarely on inappropriate, careless human activity (article in Croatian).

'Man's activites to blame for bat decline'

Bats are strictly protected in Croatia, as in other European countries. According to the Law on the Protection of Nature (Zakon o zaštiti prirode - in Croatian), there are fines up to 200,000 kunas for disturbing, capturing, wounding or killing bats, and for damaging or destroying their habitats. There is also a separate fine of 1,000 to 4,000 kunas for each killed bat. Apart from the national law, since 2000 Croatia has also been party to the international agreement for the protection and conservation of European bats, entitled UNEP / EUROBATS. In the Sixth National Report on ther Implementation of the Agreement covering 2010 to 2014, the measures being undertaken in Croatia to monitor and protect bats were described. Most of the activity is on the mainland. Toxic timber treatments were given as a subject of special concern, but it seems there has been little specific study on the effects of pesticide use.

A single pipistrellus kuhlii. Photo courtesy of the Croatian Natural History Museum

The law takes into account deliberate and wilful damage caused to bats, but there is little in the way of an adequate system of control to prevent the harm done through pesticide use, building works and renovations, tourist developments and tree-felling. Bats can live for over 30 years, but they reproduce slowly, so any deaths of young bats in a colony causes a rapid decline in numbers. Protection measures are urgently needed. Every local council should initiate projects to provide adequate habitats for bats. Youngsters should be encouraged to observe bats and record their numbers, to raise awareness at local level.

We need these important and fascinating creatures. Their insect-eating capacities are an invaluable service to human health. With due effort and care, we can re-create the conditions which allow bats to thrive. They will repay the favour with infinite interest.

© Mirko Crnčević and Vivian Grisogono 2017

A Croatian version of this article by Mirko Crnčević was published in the magazine 'Dobra Kob', issue 184, January 2017, pp 52-55

Media

Bats hunting their prey BBC Earth
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