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April 2003. Bats can be a problem when they live in buildings, colonising the space between roof and ceiling. They can be noisy and their dropping can stain the walls. Many solutions have been suggested, based on practical experiences.
The most common suggestion is to wait for the bats to leave for their evening foraging and block up the exist/entry holes with timber or mesh (one inch mesh is sufficient). One problem with this method is that the young are starved to death. On return, and finding the entrances blocked, the bats will find other places to spend the daytime. This of course shifts the problem elsewhere!
Spraying the colony or the general area of the roost with hot pepper or garlic extracts to repel the bats was also suggested, but was not an idea that received much support because it was liable to cause the bats harm. Other suggestions were to keep a pet owl, to put a low wattage light bulb in the roof space and to keep this on all the time, to remove or prune fruit trees that might be growing nearby, putting citrus (lime) branches on the floor as the bats do not like the small or the thorns(!).
The problem of bats in botanic gardens underlines the damage that they can do and the difficulty of managing the colonies. The situation is described in Managing Grey-headed Flying-foxes in Melbourne’s Royal Botanic Gardens on the Gardens’ website. Flying foxes (Pteropus poliocephalus) have badly damaged many trees, as they have in The Royal Botanic Gardens of Sydney.
Flying foxes have been observed in Melbourne sporadically for over 100 years and, since the mid-1980s, there has been a permanent colony in the Royal Botanic Gardens. Numbers have steadily increased since then, partly in response to the creation of a reliable food supply and changes in habitat elsewhere. There are now up to 10,000 flying-foxes roosting in the Gardens year-round, rising to over 30,000 in autumn.
Due to the increasing numbers of flying-foxes roosting in the Gardens, particular areas, such as the historic Fern Gully, are being damaged. This small area of rainforest is a sensitive, man-made, habitat that cannot withstand the stress of the large numbers of flying-foxes. At peak times, the flying-foxes inhabit trees across a fifth of the Gardens. Their roosting damages the trees, particularly the older ones, and has a long-term effect on the trees and the plants underneath.
To manage the population, The Victorian Government has adopted a plan to protect the Royal Botanic Gardens while providing an alternative roost at Horseshoe Bend in Ivanhoe. Bats are removed from the Gardens and taken there. Non-harmful measures are being introduced at the Royal Botanic Gardens to disturb the colony, for instance, the use of electronic and percussive noise in combination with visual effects using fluorescent flags on long poles and wind-blown streamers. Disturbance measures are used for 30-45 minute periods at dawn and dusk over 7-10 days. These have been designed to protect the welfare of the flying-foxes and to have minimal impact on visitors. Noises, flags and other visual effects being used in the disturbance program have been tested and meet health and safety requirements.
This type of Flying-fox management has never been attempted before and is of world significance. It is a collaboration between the Department of Sustainability and Environment (DSE), Parks Victoria, the Royal Botanic Gardens Melbourne, Zoos Victoria, Banyule Council and the community.
An article in New Scientist 29 March 2003, ‘Night of the mosquito hunter” concerns bats for mosquito (and malaria) control. An interesting, historical article about one person’s quest in about 1910 to move a colony into a custom made bat roost, near a lake where mosquitoes were a menace.
The article reads: “He decided to try music…. A brass band suggested itself. From hundreds of recordings he picked the Mexico City Police Band’s rousing rendition of Cascade of Roses, on account of the large number of reed instruments and some blatant high notes of cornets.
With a phonograph he tested his bat scarer. … at 4 am … The bats began to return from hunting. They circled the house a dozen times, then fled for good.” And the bats moved into the home specially made for them.
The website: www.batcon.org/home/default.asp (Bat Conservation International) is useful.
Later, January 2012: the value of bats is provided in a post by Plantwise – Why we should all be batty about agriculture. And in the same month there is an article on the devastation caused by the white-nose syndrome (caused by a fungus) to bat populations in the USA – nearly 7 million: summitcountyvoice.com/2012/01/18/white-nose-syndrome-has-killed-up-to-6-7-million-bats/
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