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Hanging out at a bat hospital: when tragedy turns baby bats' worlds upside down, volunteers come to the rescue.

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A colony of bats hangs from tree branches in the Australian rain forest. Suddenly, a female bat loses her grip; she crashes into the underbrush with a baby clinging to her. Luckily, Jenny MacLean, coordinator of the Tolga Bat Hospital in Queensland, Australia, has been searching the ground for fallen bats. Maclean knows what knocked the bat off the tree: A tick has embedded itself in the bat's skin and paralyzed it, making the bat unable to hold on. She plucks the tiny tick off the fallen mother bat and then injects her with an antitoxin to counteract the tick's poison. Another volunteer from the bat hospital wraps the week-old baby in a cloth and sticks a rubber pacifier in its mouth to comfort

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The volunteers found the mother in time to treat her so she can be reunited later with her young pup. But for many bats, the tick's bite proves deadly. Every year, volunteers with the Tolga Bat Hospital face the challenge of raising and releasing hundreds of spectacled flying foxes (Pteropus conspicullatus) orphaned by the ticks.

PARALYZED POLLINATORS

Two hundred thousand spectacled flying foxes swoop over forests in northern Queensland, where they're listed as a threatened species in danger of dying out. In the past, the number of these fruit-eating bats has plummeted as humans cleared their rain forest habitat. In addition, farmers killed the winged mammals to keep them from feasting in orchards.

Today, laws protect both Australia's remaining rain forest and the spectacled flying fox, which plays an important role in the rain forest. They pollinate flowering trees as they move from blossom to blossom, licking the flowers' sweet nectar and inadvertently spreading pollen. The bats also disperse, or scatter, fruit seeds by swallowing them and then depositing them elsewhere through their droppings. "Those dispersal and pollination services are vital to the forest's survival," says Louise Shilton, a wildlife ecologist with Commonwealth Scientific and Industrial Research Organisation Sustainable Ecosystems in Queensland.

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A mystery arose in 1986 when these important pollinators began dying on Australia's Atherton Tablelands, an area in Queensland high above sea level. In 1990, researchers discovered the problem: paralysis ticks (Ixodes holocyclus). As these tiny parasites--which can grow as wide as the tip of a pencil's eraser--feed on spectacled flying foxes' blood, they inject a neurotoxin (see Nuts & Bolts, p. 11). This nerve poison paralyzes the bats, causing them to fall from the rain forest canopy, or second-highest tree layer. Eventually the paralysis stops the bats from swallowing or breathing. The ticks strike mostly in spring, when the bats are camped at roosting sites where they raise their pups. Researchers think the bats pick up ticks when they fly down from the trees to feed on the fruit of low-lying bushes--right into tick territory.

Because the ticks can thrive only in certain climates, the paralysis problem in bats occurs in only a couple of areas on the Atherton Tablelands. "It is a peculiar situation up here," Shilton says. Spectacled flying foxes in other areas haven't been affected.

PLAYING BAT MOM

In the tick-infested areas, it's a catastrophe. MacLean searches the rain forest roosting sites twice a day during tick season, looking for paralyzed victims. She never comes away empty-handed. "In a bad year, there was one colony we'd go to, and we'd come out of every search with 30 babies," she says. The youngest pups are found holding tight to their sick mothers, but older pups often hang alone in the canopy and cry out. The volunteers rescue the ones they can reach with ladders and poles.

Back at the bat hospital, volunteers try to imitate the way the pups' mothers would care for them. For the first few weeks, pups in the wild cling to their mothers. "They just want to be cuddled," MacLean says. "So the volunteers walk around all day with baby bats hanging off them or resting in their shirts."

They feed the orphans milk from bottles. To make sure the pups are getting enough nourishment, volunteers monitor their growth by weighing the bats and measuring the length of their forearms. They also insert a microchip containing an identification number beneath the pups' skin. A handheld scanner that can read the microchip helps the volunteers tell the bats apart.

BACK TO THE WILD

When pups in the wild reach about 5 weeks of age, they hang out in the trees while their mothers find food. To simulate this experience, MacLean puts 5-week-old orphans in a large cage, where they can hang together and learn to flap their wings. When they start flying--at around 3 months of age-it's time to go back to the rain forest.

The volunteers put 10 to 15 flight-ready orphans into a cage with food and hoist it up into the canopy. There, the bats hang for a few days to get re-acquainted with life in the forest. Then volunteers release the pups. For about 3 months, volunteers hang fruit outside the cage for the released pups to munch on.

MacLean doesn't know what percent of the released orphans survives, but at least some thrive. She knows this because she uses her handheld scanner on adult bats coming into the hospital with tick paralysis to see if they contain a microchip. If she spots a microchip, MacLean knows the bats had been caught previously. She treats them and releases them into the wild again, when she puts out the release cage, released bats from other years often come back for a meal. "That's always satisfying," MacLean says, "because you know that what you're doing can work."

nuts & bolts

A neurotoxin is a chemical that targets the body's nervous system (body system that includes the brain, spinal cord, and nerves). It specifically acts on neurons, or nerve cells, which carry electrical signals up the spinal cord to the brain. Scientists believe that tick paralysis is caused when a feeding tick injects a neurotoxin into the victim's bloodstream. The toxin keeps motor signals from reaching the brain, resulting in paralysis and possibly even breathing difficulties or death.

it's your choice

1. What organism is responsible for a potentially deadly form of paralysis in bats?

(A) poison ivy

(B) flying foxes

(C) ticks

(D) cockroaches

2. What is one reason that volunteers insert a microchip into the bats?

(A) to weigh them

(B) to coax off ticks

(C) to identify them

(D) to comfort them

3. When volunteers find a bat with tick paralysis, what do they do first?

(A) inject the bat with an antitoxin

(B) pluck the tick off the bat

(C) insert a microchip under the bat's skin

(D) measure the bat's forearm

ANSWERS

1. c

2. c

3. b

PRE-READING PROMPTS

* Sick bats have been found plummeting to tile ground from trees in Australia. What do you think is making the animals sick?

* How are bats beneficial to humans?

DID YOU KNOW?

* The spectacled flying fox got its name from the pale yellow-colored fur that circles its eyes. This fuzz makes the bat look as if it is wearing glasses, or spectacles.

* Spectacled flying foxes live in camps consisting of several thousand bats. These bat species very rarely sleep, and they are known to be vein chatty. Scientists have described their camps as being deafeningly loud with squawking noises.

* Pups rescued by the Tolga Bat Hospital are fed infant fornmla for human babies or cow's whole milk.

* Each year, the Tolga Bat Hospital takes care of between 100 and 200 orphaned pups.

CRITICAL THINKING:

* How might the extinction of certain animal or plant species affect your life? Explain your reasoning.

CROSS-CURRICULAR CONNECTIONS:

GEOGRAPHY: Australia is home to several unique species. Have each of the students pick an animal that is indigenous to Australia, and then have them create a fact sheet about the animal. Each fact sheet must include a amp showing the animal's distribution range, as well as information about the climate in which the species thrives. Be sure to include the animal's scientific name.

RESOURCES

* For information about bats in Australia, visit this Web site from the Australian Museum: www.amonline.net.au/bats/index.htm

* To learn more about saving endangered bats, visit the Web site of Bat Conservation International at www.batcon.org/

DIRECTIONS: Fill in the blanks to complete the following sentences.

1. Ticks have been found to cause--in spectacled flying foxes. When a bat is found with a tick embedded in its skin, scientists pluck the tick off and then inject the bat with--to counteract the tick's poison.

2. Baby bats are called--, and they are raised in--sites. Baby bats start flying at around--old.

3. About 200,000 spectacled flying foxes live in northern Queensland in this country:--. There, they are listed as--in danger of dying out.

4. Spectacled flying foxes--flowering trees as they move from blossom to blossom, licking the flowers' sweet--and inadvertently spreading pollen. The bats also help--, or scatter, fruit seeds.

5. A--is a chemical that targets the body's nervous system. It specifically acts on --, or nerve cells, which carry electrical signals up the spinal cord to the brain.

Answer key

1. paralysis; antitoxin

2. pups, roosting; three months

3. Australia; threatened species

4. pollinate, nectar; disperse

5. neurotoxin; neurons
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Article Details
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Title Annotation:LIFE ANIMAL ADAPTIONS
Author:Adams, Jacqueline
Publication:Science World
Date:Oct 22, 2007
Words:1540
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