In recent weeks the flying-fox colony that takes up residency along South Creek in Windsor has multiplied in size.
Literally thousands of the creatures can be seen lining the trees along the banks, and moving around during the day.
A colony has always found a home there throughout the spring and summer months, drinking from the river and setting off on their nightly quests for food, but not in such a volume.
The colony's distinctive smell and loud chirping has caught the eyes and ears of residents and passers by.
Windsor resident, Robyn Will, whose house looks out over the creek, noted that the colony had always existed but never in this size.
"They're noisy," Robyn said. "We quite like them. They've always been there ... we've lived there for about four years and there has always been a colony there.
"Each year at this time the colony grows bigger, but this year it is unprecedented.
"My husband spoke to one of our neighbours, who has lived here for sixty years and she said that she's never seen anything like it.
"It's noisy, but it's quiet during the night, so that's a bonus.
"I don't know how the bats get any sleep throughout the day ... I'd hate to be one of them."
Robyn said she had found that her and her family's schedule had aligned with the bats.
"Every summer the kids know to go to bed at bat o'clock," said Robyn.
She said that "bat o'clock" was when the bats took off, shortly after 7pm each night.
"We like watching them all fly over," Robyn said. "There is a constant blanket of bats and they all fly off to get their food I assume, flying up towards the mountains.
"There is this sort of cat wee smell in the air. But it's only when they fly off. Throughout the day you can't smell anything.
"They are flying around a lot more during the days but I find that it's usually when something startles them like a truck driving past across the Fitzroy Bridge and beeping its horn.
"Or some of the people who are camping permanently behind the Jolly Frog ... they bang and clang things ... and they fly away.
"When it starts to get hotter we see them throughout the day flying down to the water and scooping up water from the river to try and keep hydrated."
Flying-foxes are known to carry a couple of serious diseases specifically the Hendra Virus and Lyssavirus.
Hendra virus can be carried by flying-foxes, though this does not mean that all have it.
It is transferable from bats to horses and horses to humans.
Veterinarian Dr Cillian Coleman said: "It's a dangerous disease which is notifiable, meaning if it is found the government must be told".
"The disease has a huge array of possible symptoms, including colicky behaviour, respiratory signs and neurological abnormalities.
"From horses it can be spread to people. It has a very high fatality rate in people."
Henrda has been mostly reported in Queensland but has been travelling south into NSW.
"There is a vaccine and it is strongly recommended that people get their horses vaccinated," said Dr Coleman.
"In some places vets will opt to not treat some horses if they are not up to date with Hendra vaccination due to the high risk of vets coming into contact with the virus.
"It started in Queensland but has been moving further south. In June the disease was recorded in a mare in Scone.
"This is scary because it is by far the furthest south it has been diagnosed and is the hub of a large part of the horse industry in NSW."
The Hawkesbury Equine Veterinary Centre shared the Gazette's photo of the colony which was posted to Facebook on October 16.
The centre added: "Bats are an important part of our ecosystem. They unfortunately have been shown to carry the lethal virus Hendra. We would like to remind our clients to keep feed and water away from trees that bats can land in. There is also a vaccine available registered to help prevent Hendra virus in horses. Hendra virus is a zoonotic disease that can cross from horses to humans and dogs and is usually fatal for the horse and has killed people as well."
The other concerning disease, Australian Bat Lyssavirus (ABLV), was found while completing the program scanning for Hendra in the 1990s.
"It has been shown to infect humans," said Dr Coleman.
"Bites and scratches with 100 percent fatality. Very closely related to rabies."
"ABLV has also been found in horses but not in other animals, though it is very strongly recommended to keep all pets away from bats.
"Despite this, vets think it is rare that it will spill over into domestic animals regularly."
One reason that has been suggested for the large growth of the Windsor flying-fox colony, is the fact that their birthing season occurs during the spring months.
Others have made note that the colony that used to be in Yarramundi has not returned this year.
It has raised the question of whether this colony has joined Windsor's creating a super colony.
WIRES have noted that there has been a large amount of migration south from colonies that have been displaced due to heat and bushfires in Northern NSW and Queensland.
WIRES have said: "if you see a sick, injured or orphaned flying-fox please keep your distance, do not touch it or try to contain it. Please keep any pets and other people away from the animal as well".
The organisation asks that concerned residents contact WIRES and that they avoid all contact with flying foxes, injured or otherwise, if possible. The hotline is 1300 094 737.
Nina Hardy: Oh so beautiful! How lucky we are to have them here?
Dani Elle: I saw them the other day and I've never before seen bats during the day! Wow!
Jackie Evenden: I saw them yesterday at 5pm. I had to look at least twice to make sure I wasn't seeing things!
Matt Peters: I was in Woolies last night an you can smell them all the way up there all the way through Windsor.
Ingrid Layton: Bats carry the Hendra virus! Not something to have in great numbers near homes!
Tabatha Hunt: Most likely displaced from another region where they have been water cannoned or other.
Debbie Ryan-Cook: Their dropping will ruin the paint on cars, bloody nuisance.
Margaret Eggers: Filthy disgusting stinking flying rats should be extinguished. Another green thought bubble of destruction being protected.
Alison Burrell: I heard them quite loudly in my gum tree blossoms last night. Kept the dogs up too.