REPORT FROM TOLGA COLONY
by Jenny Maclean

(from the FFNFF Newsletter, Edition 3, October 1996)

Have you ever experienced the wonder of a colony of fruit bats flying out at dusk? They can number into many thousands and take 30 minutes to fly overhead. Watching from within the colony itself, there seems no rhyme or reason as to which bats become restless and leave first. Their wings create a breathy beating through the air and they are magnificent.

Some people have the privilege of knowing these "primate-like" mammals intimately. Like all fruit bats, the Spectacled flying fox, Pteropus conspicillatus, is protected by law in Queensland. A colony of these bats moves into the Atherton area during the birthing season each October/Novernber and occupies a remnant of rainforest beside the Tolga Industrial Estate. Unfortunately, this is also the season for adult paralysis ticks and sadly, many young flying fox are orphaned when their mothers succumb to the toxic saliva of the Australian paralysis tick, Ixodes holocyclus. We collect these orphan babies for fostering out to human carers.

With the help of friends, I try to search the colony whenever I can after or before work. Searching the colony is not usually easy, especially up the northern end of the scrub. The rainforest itself may have stinging trees (an extremely painful and long-lasting experience,), wait-a-while vines catching at your clothing or thick understoreys, and of course leeches and thunderstorms. We collect the bats in picnic baskets with lids. Orphans are often heard screeching in the trees, sometimes too high up to rescue. Others are still on their mothers lying on the ground or caught up in foliage and creepers, no longer able to hang.

The ticks are usually quite easy to find and are killed by insecticide or mutilation with tweezers. As soon as possible, preferably at the colony, the bat is given an injection of tick anti-venene, usually intravenously into a small wing vein. A small amount of anti-venene is also injected at the site of tick attachment. Measures are taken to lower the body temperature, as the toxin is then less active. We work under the supervision of local veterinary surgeons and sometimes other medical procedures are necessary.

Once back at base, first aid measures are completed. The bats are searched for maggots, fly eggs and other vermin from being down on the forest floor. The babies are marked so that they can be identified later. This is especially important if their mother survives as the babies can then usually be reunited. The babies need to be introduced to the bottle, as most haven't had a decent feed for some days. Generally, these wild bats are extremely trusting, but a hefty bite is not uncommon. Foster parents are readily recognised by the generous amount of fine scratches on the backs of hands and forearms! These usually settle down as bats and humans get to know each other.

Last year, I collected up to 4 or 5 tick paralysed bats each search totalling about 30 to 40 bats and 15 orphan babies. After treatment, I sent them on to the Zillie Falls and Whiteing Road Bat Hospitals.

The orphans that are fostered out remain on bottle feeds for at least 2 months, 4-5 feeds a day. Fruit is introduced at about 10 weeks. They are best fostered out at least in pairs. They are colony animals and need their own species. Bat babies readily bond with their foster parents, as well as to each other. It is a delight to get to know their individual personalities. We chart their growth (forearm length) and weight. I take mine to the local post office to be weighed as their scales are accurate.

The babies I've fostered over the last 5 years have initially weighed 70-100 grams and had forearm measures of 65-70 mm. Up to 4 weeks of age, bat babies cannot regulate their own body temperature and remain on their mothers. For this reason, I like to wear my babies as much as possible between 2 shirts, with a belt. At night, they are wrapped in nappies and on the Tablelands, they often need a source of warmth, such as a hot water bottle containing warm water, an electric blanket on a mid setting or a 25 W light bulb in a tin can with a wool jumper covering. By 5 weeks of age, the baby bat is too heavy for mum to fly out with, and is left in a creche tree at night with other babies. At this stage, my foster bats are hanging in the bathroom at night. They still need to come to work with me for regular feeds and usually hang on a curtain. By 10 weeks, the babies begin to hang free of mum and interact with others. By 16 weeks, the juvenile bats fly out with the colony and learn to eat fruit, but may suckle occasionally.

By the end of February, the babies go into a release cage for release back to the wild. Time is allowed in the cages for socialisation before release. The cages are then opened at night and the babies mix with the wild bats. Many will return in the morning to roost and get a feed before flying out the next night. Slowly, they learn from the wild bats to fend for themselves. The juvenile bat then, like all fruit bats, becomes extremely important for the dispersal of rainforest seed and hence, the survival of the rainforest. Foster parents know that their release back into a wild colony is the aim of the game.