Northland bird nurse Lily Holmes said the Ngunguru wastewater treatment plant was a "green sea of dead birds".
A “horrific” outbreak of avian botulism in Northland has killed hundreds of ducks, including up to 80 threatened species.
The Department of Conservation [DoC] has confirmed the outbreak led to the death of between 70 and 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.
DoC representatives, Whangārei District Council [WDC], Fish and Game and local iwi Ngātiwai met last month to discuss options to prevent it happening again.
“Pāteke and other waterfowl have roosted on the ponds for many years without incident, until now,” DoC Whangārei operations advisor Nigel Miller said.
“It’s a significant blow for pāteke – the total number of deaths may represent up to 3% of the total New Zealand population.”
Pāteke are rare and restricted to coastal areas of eastern Northland, Aotea Great Barrier Island and several other locations around New Zealand.
They were listed as nationally endangered until 2008, when the conservation status was changed to “at risk – increasing” because of efforts to halt their extinction.
Northland Bird Nurse Lily Holmes said she and several other volunteers had “scooped up” around 70 dead ducks, along with some eels, from the treatment plant since early January.
They included native grey ducks, paradise ducks and pāteke, she said.
“When I first arrived on the site, my heart was completely shattered looking out over this green sea of dead birds,” Holmes said.
“It was the most horrific thing I have ever seen.
“Before we went there, a few other people were trying to collect dead ones – at one point there were hundreds.
“It’s good I managed to save a few, but it was a pretty shitty situation.
“It definitely took its toll on all of us, seeing that amount of dead birds.”
Avian botulism is a severe, often fatal bird disease triggered by environmental conditions that prompt a bacteria, typically found in warm, stagnant waters.
It causes progressive muscle paralysis, often leading to drowning, with high mortality rates.
Holmes, a vet nurse, said more than a dozen ducks were brought into her clinic for treatment: “I had so many in the clinic I couldn’t leave.”
She said she tried to save as many birds as she could.
This involved putting them on intravenous fluids, flushing out their stomachs several times a day to stop the absorption of the neurotoxin that causes botulism, and oxygen therapy.
Holmes managed to save about 10 birds, which had since been released.
She said local authorities should take action to stop another outbreak.
“The only way to stop more ducks dying is to remove the dead ones.
“Council should be doing frequent monitoring of bacteria and parasite levels in the water, or they should cover the pond and not let any animals go in there.
“It is wastewater and it’s exposed. There’s livestock in the paddock next to it, they could get affected too.”
Miller said the Department of Conservation was notified of the event on January 5 but was required to wait for the results of a highly pathogenic avian flu test before acting.
“Once a negative result was confirmed on January 9, staff visited the plant and removed three infected pāteke and one New Zealand shoveller duck so they could recover in care.”
The Department of Conservation buried the bodies of the deceased birds on site, according to guidelines to prevent further contamination, Miller said.
It intends to regularly check the ponds for any further carcasses and work with WDC to remove them, Miller said.
“DoC will work with the council to develop an agreed strategy to prevent further impact on waterfowl, particularly the threatened pāteke.”
A WDC spokesman said instances of avian botulism in council wastewater ponds were rare.
“However, we have shared water samples with both Watercare and Niwa Hamilton to check for any possible toxins that could have contributed to the outbreak.
“We are expecting results within the next two weeks.”
The council spokesman said heavy rainfall would have diluted bacteria in the ponds over the last week and a half.
“However, we will be reviewing our procedures and eagerly await water testing results.
“Should this detect toxins that could have led to the outbreak, we will assess whether any changes to treatment processes are needed.”
The council spokesman said covering the ponds was “not an option” as this would kill the oxygen producing algae, which is an important part of the treatment process.
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.