Royal Albatross Centre staff have recorded 250 dead red-billed gulls this season, some having been squashed by visitor cars in the car park.
Most of the dead birds were chicks and at least 125 had been found dead outside the colony, including in the car park.
The native birds number just 60,000.
Centre manager of operations Hoani Langsbury said it was unclear whether the chicks had died before being run over, but there could be up to 500 birds in the car park at any one time so visitors needed to take care.
"Don't expect the bird is going to fly away. They can't fly a long distance. Flying is something they're still learning. [If] they can't fly away, they have to run. Give them time to move out of the road.''
Although staff had not seen red-billed gulls being run over, finding squashed birds was common, due to the fact that the car park was the main flat area below the colony.
"We mostly go round and pick them up because we don't want to encourage more predators,'' Mr Langsbury said.
Feeding the birds was also a problem and gulls congregated in areas where this was happening, he said.
If chicks were fed it led to them not being able to fend for themselves and in turn, staying in the car park area.
The colony was growing, which also meant more deaths.
"We still have the only gull colony in New Zealand that's not in decline,'' Mr Langsbury said.
"I think that's because we do a lot of work there with regard to predators.''
Most visitors to the centre were "trying to do the right thing'' and Mr Langsbury said staff had observed people guiding others around birds when trying to park.
The centre was working with the Department of Conservation to come up with a plan for stopping red-billed gull deaths, including new signage.
At this stage, there was no plan for creating another flat area for fledgling chicks, Mr Langsbury said.
Taiaroa Head had 2200 nesting pairs of red-billed gulls and about 4000 chicks, up from 1600 nesting pairs and about 3000 last season.
About 400 chicks did not fledge last season.
