Nelson's Fifeshire Rock is lit by a sequence of 13 colours thanks to a Civic Trust project launched on Tuesday night.

Adverse effects on roosting birds at night has led to a plea to turn off the lights at Nelson's Fifeshire Rock.

Gillian Pollock of Nelson Forest and Bird has expressed her concern over the impact that the City of Nelson Civic Trust's illumination may have on the landmark's most common visitors, the spotted shag.

Pollock also queried whether all environmental considerations were looked into ahead of last week's switch-on.

MARTIN DE RUYTER The effect of light projected onto Fifeshire Rock is a concern for bird advocates who say the spotted shags who dwell there are being driven from their favoured habitat.

"There are quite a lot of people who are really concerned and quite keen to see the lights go," she said.

READ MORE: Civic Trust lights up Nelson's iconic Fifeshire Rock

She sent a letter to a number of organisations — including the Civic Trust and The Nelson Mail — outlining her issue with having the lights shining directly on them.

MARTIN DE RUYTER The rock, lit blue.

"For a very long time Fifeshire rock has been an important habitat for spotted shags... It is incomprehensible that this special wildlife rock is to be illuminated," the letter read.

The spotted shag and closely related Pitt Island shag are the only yellow-footed shag species endemic to New Zealand.

The winter months saw thousands come into Tasman Bay from breeding grounds around Banks Peninsula where they roost in breakwater and the outside of Pepin Island after a day spent fishing.

STEVEN WATKINS Fifeshire Rock at sunset.

They are entirely marine feeding birds in waters out to 16 km.

Spotted shags generally roost and nest on rocky outcrops or on cliffs but unlike other shag species they do not nest in trees.

Pollock said beyond Fifeshire Rock there were very few of these habitats in the Nelson area that are suitable because the cliffs have to be quite stable.

"It was really quite special having a roost site right within sight of the city," she said.

"You can go by that rock during the day and there may not be any shags on it at all because they all go out to feed, and just on dusk they start coming back in again - during the night the rock will pretty much be covered with spotted shags, and people who don't look at that intently would probably miss all that."

While Nelson Ornothologist Peter Gaze did not wish to be drawn on impact of lights on the birds roosting, he suggested that illuminating Fifeshire Rock over the summer months would pose little to no impact on the shag population.

"The spotted shag influx in Tasman Bay is a winter occurrence - there would be hardly any birds on the rock in summer and it would be hard to imagine an adverse affect on that half of the year," he said.

The Civic Trust chairman, Roger Nicholson, said

the trust's policy was to communicate directly with everyone who communicated with them rather than through the media.

The trust would respond directly to Pollock who wrote on behalf of Forest and Bird and also to one Rocks Road resident.

NCC group manager strategy and environment Clare Barton said the Civic Trust had to get New Zealand Transport Agency approval for a licence to occupy the road reserve but no resource consents were required from the council.

Barton added that the council did not own any of the land involved in the project.