A number of critically endangered black-billed gulls have been killed by drivers exploring a Canterbury braided river.
Images supplied to 1 NEWS from a trail cam show a number of 4WDs and a person on a motocross bike driving through the birds.
Ashley Rakahuri Rivercare Group member Grant Davey says there have been half a dozen of these incidents over the last few days.
"On at least one of these occasions birds have been killed - up to about a dozen."
Davey says this sort of behaviour often happens on braided rivers but is not caught on camera.
Chair at Environment Canterbury Jenny Hughey backed up Davey's comments, saying 10 birds were killed in one of the incidents last week at Ashley Rakahuri Regional Park.
"This is extremely disappointing and unacceptable behaviour, and we are exploring what our enforcement options are," she told 1 NEWS.
"These beautiful birds are unique to New Zealand, mainly breeding on South Island braided rivers, are ‘nationally critical’ and rapidly declining, and are the most threatened gull species in the world.
"With current trends they would further decline of around 70% over the next 30 years.
"However, this year has been a very successful breeding season in the colony, and we work closely with the Ashley Rakahuri Rivercare Group and the community to keep it safe."
Hughey says the area is monitored closely and there is signage up to alert people not to drive through the area.
"The measures we, and the Ashley Rakahuri Rivercare Group, have taken this season have been largely successful and the majority of park users have been respectful and avoided this area.
"The nesting area has been cordoned off since September to protect the colony, and will be open in two weeks when the birds have fledged.
"The nesting areas are also protected by the Wildlife Act, which is administered by the Department of Conservation."
If anyone sees anyone disturbing these colonies they can call Ecan on 0800 324 636.