Whangārei dam closed to public after more bird deaths, avian botulism suspected

Whau Valley Dam is temporarily closed to the public. Photo / WDC

A second outbreak of avian botulism in Northland is believed to have killed 25 birds.

Whangārei District Council is investigating after seven dead birds were found at the Whau Valley Dam on February 14.

The dam has been temporarily closed to the public.

Another 18 dead birds were found during checks on Monday and Tuesday.

Council water manager Andrew Venmore said testing was underway to rule out bird flu, however avian botulism was the likely cause.

“We have notified relevant stakeholders and hapū, and will work with them as more information becomes available.

“Any dead birds, predominantly paradise ducks, are being isolated before being buried.”

Avian botulism is a severe, often fatal bird disease triggered by environmental conditions that give rise to a bacteria, typically found in warm, stagnant waters.

It causes progressive muscle paralysis, often leading to drowning, with high mortality rates.

Earlier this month the Department of Conservation (DoC) confirmed an avian botulism outbreak killed up to 80 pāteke (brown teal), a threatened species endemic to New Zealand, at the Ngunguru wastewater treatment plant on the outskirts of Whangārei.

Another 170 ducks were also reported to have died, including native grey ducks and paradise ducks.

Northland bird nurse Lily Holmes and several volunteers retrieved around 70 of the dead ducks, along with some eels, from the treatment plant.

Northland bird nurse Lily Holmes and several other volunteers retrieved around 70 dead ducks from the Ngunguru wastewater treatment plant earlier this month.

Holmes, a vet nurse, treated as many birds as she could at her clinic, managing to save about 10.

Holmes hadn’t heard about the recent outbreak, but said it was “interesting” another had occurred in Whangārei.

“There must be a serious problem going on.

“It could be if the paradise ducks migrated to or from Ngunguru – they are migratory birds so that could be the reason.”

While botulism-causing bacteria rarely pose a risk to humans, pets can become ill if they eat contaminated carcasses or invertebrates.

Venmore assured the public that water from the dam is fully treated and safe.

Whau Valley Dam. Photo / NZME

Wilsons Dam had also been inspected, and there were no signs of dead birds.

The wastewater treatment plant at Ngunguru was being checked every second working day, Venmore said.

The number of dead birds had reduced, with none being found during Monday’s inspection.

“Results from water testing show algal bloom is not present in the wastewater ponds, which would otherwise indicate problematic water conditions.

“Our priority is to prevent the spread of the disease through regular checks and safe removal of any dead birds.”

Venmore said a new management plan would be worked through with stakeholders over the coming months.

Members of the public are reminded to follow safety precautions if dead birds are visible near water sources:

• Avoid contact with the ponds or dams
• Don’t handle or remove dead birds
• Keep pets away from the water’s edge or any dead animals
• Report it to Whangārei District Council on 0800 932 463.

Jenny Ling is a senior journalist at the Northern Advocate. She has a special interest in covering human interest stories, along with finance, roading, and social issues.