In Casino the bat problem is so bad that the public school has to be washed down every morning before the children arrive. “There is just so much crap,” says Richmond Valley Council communications manager Sharon Davidson.

In Mullumbimby, further north, doctors are prescribing medication to people so they can get some sleep. “It is not just at night for us,” says resident Megan Drummond. “It is all-day noise. People think bats sleep all day; they don’t. The only time they sleep is for about an hour before they take off to feed at night.”

A noise measurement survey last Easter showed that the noise from bats in some northern New South Wales towns was louder than that of nearby Bluesfest. “No one is sleeping and it really impacts our lives,” Drummond says. “The anxiety is unbelievable.”

Across the Northern Rivers, windows were being slammed shut as the summer heated up. “If you are on the phone, you can’t hear yourself talk,” says Davidson. “They stink and screech.”

Bats are social creatures, says Storm Stanford, a flying fox expert for the native animal rescue organisation WIRES. “They are chatty. They wake up and have a chat to their neighbour and go back to sleep. But their noise range is exactly the same as our hearing.”

And the intolerable noise is about to get a whole lot worse. This is their mating season.

The orgies going on in backyards and along riverbanks are a problem for councils intent on moving the colonies.

“Males are very enthusiastic about sex,” says Stanford. “So enthusiastic that they will eat enormous amounts and get very big and strong. The adult males won’t leave the camp because they want to be on display and show the females how good their genes are. To display that they are genetically fit, they shout. They stand on their branch and say, ‘Come on, girls, I have got the best genes, come over here.’ They shine their testicles up so you can see them across the camps.”

The orgies going on in backyards and along riverbanks are a problem for councils intent on moving the colonies. While the little red flying foxes that are causing the problems in Casino are not protected, they are roosting with grey-headed and black fruit bats, which are.

“Little reds are very sweet,” says Stanford, “but the problem is that they only travel with their favourite 50,000 friends. They are very family oriented. When they roost, they roost on top of each other: 20 or 30 will hang off each other. Branches tend to break.”

Casino had little problem with its grey-headed fruit bat population. The difficulties began when the little red arrived from Queensland. “As in all families, it is when their rellies visit that the trouble starts,” Davidson says. “The numbers quadruple.”

Land clearing has forced flying foxes into urban locations. And attempts at moving the colonies have been less than successful, sometimes farcical.

Efforts have ranged from continuous loud noise to bird-scare guns to helicopters to spraying with water or smoke to simply destroying the habitat. But the bats just moved to nearby colonies.

“Flying foxes are mobile,” a report by the Australasian Bat Society noted, “but show a high degree of fidelity to camp sites.”

Last year, Pittwater Council attempted to move a colony of bats that was affecting residents’ quality of life at the Cannes Reserve at Avalon.

Using a mixture of noise, smoke and lights between 4am and 6am for three weeks, and pruning palm trees and removing unsafe vegetation in four subsequent maintenance operations, the bat camp was emptied. But now that breeding season is here they are back, if in significantly lower numbers.

Getting permission to do anything to bats requires locking horns with the NSW Office of Environment and Heritage. Pittwater Council ceased its dispersal operations last October because pregnant females and babies were observed in the colony. Those shining testicles.

“Last year,” says Davidson, “we were given approval to clear vegetation from private homes and the riverbank, to put a buffer between homes and bats without disturbing the bats. There is a lot we can’t do. It is with the Office of Environment and Heritage; they are the ones that are responsible.”

In 2012 Sydney’s Royal Botanic Gardens launched a determined campaign to get rid of a bat colony that was damaging heritage-listed trees. It took three years to get permission. “We had over 60 plants and trees die as a result of flying foxes roosting,” says Dr John Martin, wildlife ecologist at the gardens.

It was a nocturnal raid. Banging and crashing industrial noise was played at full volume as the bats came in to roost in the pre-dawn hours. “These guys are returning home to go to sleep after foraging,” Martin says. “They found that there was a music concert on, so they decided to go and stay at their friends’ house instead.” Disgruntled by the party at bedtime, the bats “left within a week”.

But it didn’t stop there. “The intensity and the activity decreased but there was still an active presence for 18 months,” Martin says. “There were spotlights and people walking around and moving on the ground. You can imagine if you were a flying fox colony, if you are not used to having people there and they are walking around at 5am. It was a big deterrent.”

But there are drawbacks. “It costs a fortune,” Stanford says. “A proper dispersal takes lots of staff, people doing the monitoring, it is unfun for everybody.”

Some of the evicted bats popped over to Centennial Parklands. “Others,” says Amara Glynn, environment officer at the parklands, “went all over the country. We used radio tracking to find out where they went.” Centennial Parklands has a volunteer group that counts them once a month as they fly out each night. “In February there were 17,000. But it can be anywhere between 5000 and 40,000.”

Fortunately, the parklands already had a swamp so the bats could fit right in. “It was already a stinky environment,” says Glynn. “It is not near residents.”

Glynn adds: “It is a really nice thing to come and see all the bats flying out in the evening and swoop down on the ponds to dip their bellies in the water. That is the way they drink. They flick the water off their fur on their belly.”

In Mullumbimby, Drummond is not so sure. “Having them flying over you overnight is joy compared with when you have got the camp living on your doorstep. It is smelly, hideous and disgusting.”

At Dulguigan in the Tweed, a group of people went vigilante and cut a colony’s camp down. They discovered, says Stanford, that “if you destroy a camp, you might solve your immediate problem, but it will turn up somewhere else and be a worse problem.”

One of the difficulties is the nomadic nature of bats. “It is like people,” says Glynn. “Some are homebodies and others like to move around.”

This is, Martin says, the key factor in moving colonies. “The biggest reasons dispersals do not work is because each colony is different. So the population varies annually and it varies seasonally. In a big year of flowering there will be larger numbers in a singular colony. In a small year for flowering those animals will be hundreds of kilometres away. So when we talk about the management of a colony, we need to factor in a much larger area than the local colony. That is the challenge of this species. ”

Stanford believes that instead of futile attempts to move bat colonies, people need to adapt to them. “We have created the problem. We need to support the people. Provide insulation, get double glazing. There are much better ways of managing it than dispersals. Shoalhaven [City Council, south of Sydney] is offering their residents car covers. Different councils have different ways. There are lots of things councils can do. Singleton [in the Hunter Valley] is offering to cut palm trees. It is about making them able to coexist.”

Meanwhile, the bats are still hanging in there.