The number of birds with avian botulism has doubled this year - leaving council workers with hundreds of dead birds to pick up.
The disease festers in watering holes and a warmer and longer summer has seen thousands of birds infected.
Sitting still, unable to move, one duck has been paralysed from the feet up.
"They will look like they want to move but they actually can't," veterinarian Liz Murdock says.
Murdock has been treating waterfowl for botulism for years and says this season has been one of the worst.
"It started about November, the previous season, and this year it started somewhere around August, September, so we have an extra month and it's been pretty much non-stop," Murdock says.
The paralysis means birds are prone to predator attacks, parasites and drowning after they eat a toxin produced by the botulism bacteria, which thrives in warm water and is made worse by feeding them bread.
"And it's still pretty warm even in autumn, we think that's a big reason why we've had more birds with botulism," animal lawyer and charitable trust BirdCare Aotearoa spokesperson Bianka Atlas says.
Atlas says BirdCare Aotearoa has treated 600 birds so far, double the amount of last summer.
It's mostly ducks, geese and swans that are affected, but BirdCare Aotearoa says this year that's spread to native species too.
While just a handful of birds remain receiving intensive treatment, earlier this year the cages were full.
At the peak of the outbreak in January, several of the birds were caged together for emotional support.
Vets provide the birds with fluids and even physical therapy.
"This little guy has been with us for two weeks now and he's just starting to come right," Murdock says.
There is good news - BirdCare Aotearoa says with intervention they have a 95 percent survival rate for mallards.
"We just urge anyone who sees a bird and they suspect it may be suffering from botulism to bring them to us as soon as you can," Atlas says.
So these little guys can get back to doing what they doing best.
