Avian botulism the likely cause of more than 100 duck deaths near Napier waterways

Hawke’s Bay Fish & Game has tested the water after dead and distressed ducks were found in Napier waterways. Photo / Paul Taylor

Experts say it’s likely that more than 100 dead ducks found around creeks and streams near Prebensen Drive in Napier died of avian botulism.

The ducks found early this month were reported to Hawke’s Bay Fish and Game, which sent them for testing.

Wendy McDonald, manager of biosecurity surveillance and incursion investigation at the Ministry for Primary Industries (MPI), said its role was to rule out exotic (introduced) diseases as a cause of death.

“Our testing has excluded HPI [bird flu] as a cause,” McDonald said.

“We think it is likely to be botulism, which we don’t routinely test for because it is a domestic and not exotic disease.

“Botulism outbreaks are not uncommon and happen frequently, particularly in the North Island.

“Avian botulism is a naturally occurring bird disease triggered by environmental conditions which prompt a bacteria, found naturally in soil, to produce a toxin that causes birds to die.”

Kerry Meehan, from Hawke’s Bay Fish & Game, said it was working closely with the Napier City Council and Hawke’s Bay Regional Council to collect any more distressed or dead birds.

“Recent rainfall should help reduce the conditions that allow botulism to spread. We ask the public to report any sightings of three or more dead or distressed birds to Biosecurity New Zealand and Hawke’s Bay Fish & Game.

“We remind pet owners to keep their dogs well clear of any dead or distressed birds,” Meehan said.

“We’re also awaiting the results of water quality testing.”

She said the public should report any deceased, distressed or noticeably lethargic ducks by calling (06) 844 2460 or email hawkesbay@fishandgame.org.nz

“Make sure not to touch or handle the birds. Staff will also be out checking other waterways.”

This week the Napier council warned people to keep their dogs out of the pond in Anderson Park.

It said recent tests showed the northern pond had high levels of blue/green algae (cyanobacteria), which can be harmful and might produce toxins.

“It’s super important to keep dogs away from the water, not just in the pond but also in other areas like Taipo and Saltwater Creek, where we’ve noticed similar algal blooms. We’re keeping a close eye on the situation and carrying out ongoing testing.”

Blue-green algae can grow quickly in nutrient-rich water, especially when it’s warm. Nutrients like phosphorus and nitrogen, which come from things like runoff, lawn fertiliser, leaf litter, grass clippings, and pet or wildlife waste, help them thrive. Changes in climate, such as higher temperatures and altered rainfall patterns, also encourage their growth.

LDR is local body journalism co-funded by RNZ and NZ On Air.