It may be lights out for cruise ships plying southern waters this season, following reports of unwanted passengers arriving under the cover of darkness.
Harbourmaster Kevin O'Sullivan, of Environment Southland, confirmed a cruise ship operator had approached the regional council over disoriented birds landing on the brightly-lit vessels at night.
While bird strike can be hazardous for aircraft, the birds were no match for a cruise ship, he said.
Cruise ship operators, used to sailing in "environmentally sensitive" areas such as Alaska, were keen to minimise their impact in areas they visited.
Mr O'Sullivan, in conjunction with the Department of Conservation and Cruise NZ, would aim to have protocols in place this summer for cruise ships on how to handle any bird strike.
It appeared the birds - mostly petrels and shearwaters - were attracted or disoriented by the lights of cruise ships in the dark. One possible solution was for vessels to turn off their deck lights.
Cruise NZ chief executive Craig Harris said bird strike appeared to be only a problem along Fiordland and the south coast.
A captain of Volendam raised the issue after discovering some stowaway petrels.
"I didn't even know it was a problem," Mr Harris said.
