The Department of Conservation (DoC) has released images of two men suspected of killing critically endangered birds in Rotorua.
Five black-billed gulls were found dead at Rotorua's Sulphur Bay, a breeding area, during a routine check by a DoC volunteer in November last year.
The images of the two men were captured by motion-detector cameras set up in the area to monitor the colony, and the DoC released them in a bid to track the suspects down.
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"The deliberate killing by people is preventable and [an] unacceptable risk," DoC senior ranger of biodiversity, Mariana Te Rangi, said.
"And we would like to hear from anyone who has information about the incident or can identify the men in the photographs."
In the images, the men can be seen pointing a rifle at the black-billed gulls - considered by the DoC to be the "most endangered gull species on the planet".
The rifle shown in the images could have been a BB gun, as an x-ray of one of the birds revealed a BB bullet stuck in its breast.
Killing black-billed gulls is an offence under the Wildlife Act 1953, which prohibits the hunting of them. Hunting or killing protected wildlife carries penalties of up to two years in prison or a $100,000 fine.
"These special birds are a taonga to Rotorua and are threatened with extinction," Ms Te Rangi said.
Population of the gulls have rapidly declined by as much as 80 percent, according to the DoC, resulting in the species' threat status being upgraded from Nationally Endangered to Nationally Critical in 2013.
A man was jailed in 2013 for driving a vehicle through colonies, destroying nests and killing chicks and even adult birds.
The birds can mainly be found in the South Island around rivers. In the North Island they can only be found scattered across colonies in Hawke's Bay and Wairarapa, as well as Lake Rotorua and Lake Taupo.
The DoC has appealed to the public for information on the two men allegedly involved in the birds' killing, and police are making inquiries.
Those with knowledge of them can contact 0800 DOC HOT (0800 362 468).