Bats investigation

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Going batty for a new way of preserving animal life in Zoos

The Mysteries of Chester Zoo's 'Twilight Zone' explained.

Problem: how to balance the needs of both the bats and visitors to the Twilight Zone at Chester Zoo by keeping them both comfortable.

As a rule of thumb, nocturnal animal exhibits in zoos in the past have always been somewhat of a disappointment. Many times in the past, people have tried to peer into pitch-black glass cubes to catch glimpses of elusive dark-dwelling creatures, or into brightly lit ones, that only result in the animals doing their best to hide away in the dark parts. However, advancements in understanding of animal behaviour and design of artificial habitats means that the paying public may nowadays be able to see the night-living animals that so eluded us in the past. And what animal more defines this than the bat? Bats - order Chiroptera -are either classified as megabats (Megachiroptera) or 'microbats' (Microchiroptera). The 'microbats' are the only ones that use echolocation, contrary to most belief that this 'SONAResque' method of locating obstacles and food is common across the entire Chiroptera order. The 'megabats' use eyesight and moonlight or starlight to see at night, though 'microbats' are capable of seeing with their eyes as well, usually at dawn or dusk.

Chiefly insectivores, many bats eat fruit or a combination of the two, or as is the famous (and possibly best known example, Desmondus rotundus, the Vampire Bat, on the blood of other mammals. These two important facts about keeping bats means that quite often, if to replicate their natural environment and feeding habits, ideally a group of bats with similar feeding habits should be provided, and light akin to moonlight should be in the enclosure. To see if these could be successfully implemented, I visited Chester Zoo to see the new bat habitat, labelled to visitors as the 'Twilight Zone'. From the outside, certainly, it is an unimpressive building, just a green-painted corrugated iron. Inside however, the atmosphere changes greatly. It was a dark, grey and horrible January Wednesday when I visited the zoo, but stepping into the Twilight Zone really was a change from outside -my eyes had to spend some time readjusting, and the carrot cake I had for dessert last night hadn't helped at all. When it was possible to see further than my hand at arm's length, a sign on the wall advertised the three types of bat living in the Twilight Zone. Three ... .the tourist guide and the website had only advertised two.

The Rodriguez Fruit Bat or Rodriguez Flying Fox), Pteropus rodricensis, is possibly the most important venture of the zoo's because in the wild, like many other endangered or now-extinct species, it survives in a very small, specific area of land - in this case the Island of Rodriguez, a part of Mauritius -the island once known to be the habitat of the extinct dodo.

This island is just east of Madagascar, in the Indian Ocean, and the bats live in a single valley -'Cascade Pigeon' -which is made of dense, mature rainforest trees. Frequent cyclones and vicious tropical weather mean it is dangerous for the bats to stay out in the open, which is why they live in the dense forest. However, this habitat is threatened by human deforestation, and the lack of trees main that there is also little food for the bats now in the wild. It will be referred to as the Rodriguez Bat from now on in this article 1. 'The Seba's Short- Tailed Fruit Bat (Caronia perspicillata) is the smallest bat that the zoo keeps, and the only 'microbat', the two Pteropus both being 'megabats'. It can grow to have a six inch wingspan (15 cm) and a mass that can range from a tiny 5g to 22g for fully grown males. For the purposes of clarity in the rest of this report, it will be referred to as the Seba's bat 2. The third bat type, (the one not noted on the Chester Zoo website funnily enough), is either called the Comoro Black Flying Fox, (below) or Livingstone's Bat, is the biggest of the bats the zoo has, with a fully grown adult able to have a wingspan of around four and a half feet (130cm) and a maximum weight in captivity of nearly a kilogram. (In the wild this is slightly lower; the higher quartile of weight being about 800g, though the wingspan can be much larger, up to one and a half metres). The inside of the Twilight Zone at Chester Zoo certainly belies the rather ordinary exterior. Once one's eyes adjust to the darkness, it's clear that a lot of care went into making the area around the entrance resemble a cave. Artificial rock has been set up in a way that arches over one's head, and much like in real caves, it is necessary (or it feels necessary) to duck through some of the arches for fear of cranial injury. Double plastic curtains stop the bats from escaping from the area, though a look round makes one wonder exactly why they would want to. Though the roof is still obviously corrugated iron, but the artificial rock continues around the sides of the warehouse, even creating an entire cave for the bats to roost should they want to. Shallow blue-white light illuminates the area, making it seem like moonlight (important for the two Pteropus), and when I first entered, I had to stand still for a while just taking all the sights in. The Livingstone's bats are an impressive sight to see swooping around and blotting out the light, whilst the Seba's bats simply flit around so quickly you can barely see if they're there. Wires are hung up above the 'rock' cliffs for the bats to perch, and it is obvious many do so -the wires are almost full of the three different sorts of bat, hanging and letting out their various chirps -the higher squeaks from the Seba's and the bird- like caws from the Rodriguez bats. There is a second cave, and a very dense forest area in one corner, not for access to the visitors. According to one of the staff on duty there, many of the Rodriguez bats stay there during the daylight hours, whilst the majority of the Seba's bats and the Livingstone's roosted in the cave. The second cave, the one the brave (or mad) members of the public are allowed to walk through is habitat to the chief male of the bat brood and his 'harem' of all the females.
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The forested area and all the other examples of vegetation are an attempt to make the bats more comfortable, and many of the trees are taken from the African islands the bats come from or ones near to that point as well. The fruit trees themselves that the bats fed on, most particularly across the three bat types being Tamarinds, couldn't be kept in the UK because of the heat requirements -most of the other trees in the Zone don't require as much heat (they do not need to produce such sweet and ripe fruits). Also in the ...

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