Concerns 4x4 drivers are oblivious to the damage they are causing.
Endangered native birds are at risk at Canterbury's Ashley River from people driving through black-billed gulls' nests.
Ashley Rakahuri Rivercare group member Grant Davies told Chris Lynch it's deeply disappointing given the efforts made to protect the birds.
He says his group is working to educate people to not drive along braided river beds during the nesting season.
Davies says the black-billed gull is nationally critically endangered.