ACU (Australian Catholic University)

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Issue 1, Spring 2011

Messing with microbats

Messing with microbats_thumb

Microbats go largely unnoticed due to their tiny size and quiet, nocturnal habits. Alisse Grafitti met with PhD student Leroy Gonsalves, and discovered that these winged creatures have found a friend.

"People don't give a lot of thought to bats. I guess they're not all that popular seeing as they only come out at night and have creepy connotations.

The bats I'm working with for my research though are tiny. Most of them weigh about 4 grams and can fit in a matchbox, so they're pretty cute.

I'm studying the diet of microbats that live on the Central Coast for a project funded by the NSW Environmental Trust.

My study area in Empire Bay has large areas of saltmarsh, which can support huge numbers of mosquitoes at different times of the year. Apart from nuisance biting, these particular mosquitoes have the potential to spread diseases such as Ross River and Barmah Forest viruses - which can cause rashes, fever and rheumatic pains.

A local residents group has been lobbying the local government to control mosquito numbers by spraying the larvicide Bti, which kills the mosquito larvae.

The larvicide doesn't eliminate mosquitoes completely, it just reduces their numbers.

However these mosquitoes may also be food for up to 14 rare insectivorous bat species. Before the government can give the go-ahead for spraying they need to know if it's going to be problematic for bats in the area, some of which are threatened species and protected by legislation.

So my research is closely examining the movements of these bats in association with the mosquito fauna of the area, and investigating bat diets to determine just how important mosquitoes are to their survival.

There are several ways I'm going about this.

One is radio-tracking the bats. We put little tags on their backs and release them, then track their movements, both when mosquito numbers are high, and when they are much lower.

Bats are pretty smart and a lot of them avoid traps, so we also record their echolocation call - which is a type of sonar that bats use to navigate and find prey. Another method is light-tagging, where we stick a little glow-stick on their stomach and observe where and how they fly in different habitats.

I've also been studying guano, or bat poo, to see what they've been eating. I'm using DNA techniques to give species-level identification of their prey, which hasn't been done before for bats in Australia.

So far I've confirmed that certain bat species do feed on saltmarsh mosquitoes. I am continuing to look at what the other bat species in the area are eating.  Next 'll be doing a feeding trial, giving bats different quantities of mosquitoes and other insects in order to get an insight into the relative importance of mosquitoes to bat diet.

I'm also looking to see if bats turn to eating different insects, or move to different areas, when mosquito numbers are reduced.

It's been an interesting research project, and pretty eventful.

I've been bitten by bats twice, and had to quickly get the rabies vaccine because they can carry Australian bat lyssavirus (ABL). The only two known people who've been infected with ABL in Australia both died, so I guess you could say it has a 100 per cent mortality rate.

The lack of sleep is definitely the worst part. When I'm radio tracking, it's two weeks straight of being out in the saltmarsh from sunset to 2am, and then back at it again from 4am till daylight.

The mossies are also a killer. I'll be covered up completely, usually with two layers of clothing and a whole can of aerogard, and they still get me. They have a nasty bite too.

When I first started my research project, bats did freak me out a little - it must have been the whole lyssavirus thing. But after having one of them in the palm of my hand, that all changed. They are fascinating little creatures, each with their own personality, and now I just love them."

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