Rotorua residents are being urged to share any information they have on suspected bird-poisoning at Hamurana Reserve.
The Department of Conservation said it had received reports of birds of several species found dead or dying at the reserve, on the northern shores of Lake Rotorua.
Fish & Game NZ Eastern Region had also received reports of dead ducks and gulls found in the Hamurana area since mid-March.
The birds included several red-billed gulls – a protected species – as well as mallard ducks, black shags and a cygnet.
DOC Compliance Officer Hayden Loper said the discovery of the dead and dying birds happened through mid-May, with information provided directly by two members of the public and also by a Fish & Game staff member.
Loper said current evidence pointed toward a poisoning so DOC was investigating.
Several species found dead or dying at the Hamurana Reserve. Photo / Fish & Game
"The necropsy of one bird by a local vet has revealed an unknown substance in its gut while a Fish & Game officer has found and removed a potentially toxic paste – thought to be the avian poison alphachlorolose - has been found at Hamurana Reserve, and removed."
Alphachlorolose is a narcotic used to control birds such as sparrows, mynas, blackbirds and magpies. It sedates pest or nuisance birds so they can be culled humanely.
Non-target species can be revived after ingesting the product.
It is sold under a number of brand names and forms and when the paste form is used in public places, warning signs should be installed. There is a legal obligation under the Agricultural Compounds and Veterinary Medicines Act (administered by the Ministry for Primary Industries) to use any of alphachlorolose products as specified on the label – this includes only targeting species on the label.
The use of alphaclorolose in a public place requires authority from the landowner.
Iwi Ngati Rangiwewehi, which owns the reserve, said no one had been given permission to use the product at the site, and local councils had also confirmed they had no active bird control operations in the area.
"We have two serious concerns here," Loper said.
Rotorua residents are being urged to share any information they have. Photo / Fish & Game
"Firstly, we've got a potentially toxic substance being used in a public area without the right permission, and secondly, we've got protected native wildlife being harmed as by-kill in someone's effort to control another species of bird.
"This may be a deliberate attempt to poison birds with an endemic protected species among those affected, DOC is calling on the public for information which may prove helpful to our investigation."
Ngāti Rangiwewehi Te Tāhuhu o Tawakeheimoa Deputy chairwoman Mercia-Dawn Yates said Ngāti Rangiwewehi valued wildlife and particularly any that made Hamurana home.
"As owner and kaitiaki of the reserve we have a responsibility to care for all taonga, and have not given permission for this activity.
"We want this activity to cease, and we are supporting DOC in ending this activity. Please report any information as soon as possible."
The red-billed gulls are protected by the Wildlife Act and anyone deliberately killing or harming the bird could face a fine of up $100,000 or a two-year prison sentence if proven or admitted in court.
Any members of the public with information, including witnessing suspicious activity at the reserve, should call 0800 DOC HOT or email wildlifecrime@doc.govt.nz - or Fish & Game on 0800 POACHING (0800 762 244) OR 07 357 5501.
Although relatively common – and a species most New Zealanders will be familiar with – red-billed gulls are declining in number.
The colony at Rotorua is unusual because it is inland, rather than coastal.
