Five of the gulls were dead when found while the other five were so sick they had to be euthanised, the Department of Conservation said.
Test results show the birds had ingested fatal levels of Alphachloralose, a rapid-acting narcotic bird control agent and hazardous substance.
Black-billed gulls are Protected Species under the Wildlife Act 1953, and it is an offence to hunt, kill, catch or possess them without authorisation.
DOC is now appealing for information on the poisoning, which was discovered on January 18.
Te Anau operations manager John Lucas said the deaths were a disappointing blow for the Te Anau population.
“Tarāpuka are New Zealand’s only endemic gull and their numbers are in rapid decline, especially in Southland.
"They primarily eat invertebrates and fish and are less likely to be found scavenging than other gull species. They can live for up to 29 years.
“People may be used to seeing colonies ranging in the hundreds and thousands but with introduced predators, habitat loss and changes in land use these avian fixtures of the south are in serious trouble, with some studies estimating up to 80 per cent decline in Southland over the past 30 years.”
DOC has launched an investigation and is asking members of the public and local businesses for any information relating to the use of Alphachloralose or any product containing this toxin in the Te Anau area around January 18 .
“Like kiwi and kākā, tarāpuka are only found in New Zealand and are part of what makes New Zealand special. If you saw or heard anything while out naturing on the Te Anau waterfront this summer that may help us get to the bottom of this please get in touch.”
People can report any information to 0800 DOC HOT, DOC case reference CLE-11463. Information can be offered anonymously.
- Allied Media
