What looks like an idyllic lake in Australia’s suburbs is the site of several disturbing finds. Over several weeks wildlife rescuers have scooped the bodies of dead ducks and other native birds from its waters.
“They have no visible injuries, cause of death unknown,” mystified WIRES volunteer Inga Tiere wrote on a community social media page.
She later told Yahoo News, “it’s been going on for weeks and there are dead birds all the time.”
Samples of two ducks and an ibis were collected from a lake at Mount Annan in Sydney’s southwest and sent to Western Australia for specialised testing. It’s suspected the birds fell victim to a serious condition caused by a toxin that disrupts the body’s nervous system.
Why are the birds dying on the lake?
Botulism is caused by a bacteria called clostridium botulinum which is naturally found in soil and water. It can fester undetected for months inside stagnant pools, or slow-flowing water, and then become flushed to the surface and unleash carnage on wildlife. Birds that frequently come into contact with water like pelicans, or soil like brush turkeys, are particularly vulnerable.
WIRES head vet Dr Tania Bishop told Yahoo News recent rains coupled with hot weather have sparked sporadic cases of suspected botulism across Sydney.
“I’m not surprised by it. We’ve had dry weather and then a lot of rain. It’s the perfect condition for it,” she told Yahoo News.
In 2023 there were suspected cases at the lake in the centre of the city, and around Brisbane’s airport. That same year over 700 birds were affected by the disease at one reserve in regional Victoria.
Bishop said bird deaths often go unnoticed by the public unless they perish in high numbers. Birds will often lose the ability to keep their heads above water and become prone to drowning.
Camden Council which has jurisdiction over Mount Annan has been contacted for comment.
Samples were taken from ducks found dead in the lake, which were sent for testing. Source: Inga Tiere
Extreme weather set to unleash disease in native animals
It’s just one of several concerning wildlife diseases that Bishop is concerned will become more prevalent due to predicted extremes in weather, caused by climate change.
“Climate change affects everything — water availability, food availability, the quality of trees,” she said.
“People often just think of climate change as things getting warmer, but it’s much more than that.”
The lake is popular with waterbirds. Source: Inga Tiere
Among her concerns are tropical diseases which are moving south as the weather becomes hotter and often more humid. Lorikeet and flying fox paralysis syndrome are two other debilitating diseases that are likely linked to extreme weather.
Koalas, which are expected to be extinct in the wild in NSW by 2050, are also increasingly impacted. And it’s not just fire and drought associated with climate change that is the problem.
“There is less moisture available in the soil, so it causes eucalyptus trees to lay down more oxalate crystals — it’s a stress response to protect the tree,” Bishop said.
“The tree is saying, hey look I can’t handle things eating me while there isn’t enough nutrients or water. These are then passed onto the koala, reducing the kidney function of the koala.”
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