An Aramoana resident who asked not to be named said she was concerned when she heard the bikes in the area. She took a photo of the incident at dusk during the weekend.
It appeared to be a group of young people out "having a blast" who apparently knew they were somewhere they were not supposed to be.
"As soon as they saw me taking a photo, they took off."
Three of the group of six people had bicycles and there was a dog in tow.
It appeared the young joyriders had been in the area a couple of times, she said.
It was clearly marked that vehicles were prohibited in the area, but it remained scarred by tyre marks.
She did not know if the joyride resulted in its death, but she found a dead bird with a bike’s skid mark nearby.
"It’s a shame that the young folk don’t have that connection to the land, respecting it.
"I’ve got children myself. I understand, they get bored and it’s an adventure, it’s exciting and all that sort of stuff.
"But when people are working so hard to protect that area ..."
Doc coastal Otago operations manager Annie Wallace said the Aramoana ecological area protected the most extensive area of salt marsh vegetation in Otago.
It was one of the most extensive areas of "dune slack", or wetlands lying between former dunes that were now above the high tide mark, in the country.
It was also habitat for banded dotterels, bar-tailed godwits and other birds "and is highly valued as a place to enjoy and appreciate nature".
Ms Wallace said it was an offence under the Conservation Act to enter the area with a vehicle, unless a permit had been issued for management reasons.
Doc and the local community were working together to manage the area, she said.
"This has resulted in reduced damage from vehicles as well as progressing weed control and planting programmes.
"As part of this work Doc rangers have a regular presence at Aramoana.
"Anyone who sees vehicles in the saltmarsh should report it."
