The orange-bellied parrot, one of Australia’s rarest birds, could again up-end plans for a major project in Victoria, after a study found it likes to feed at a Port Phillip Bay site Labor is eyeing off as the place for Melbourne’s next port.

But the confidential study, commissioned by the Department of Transport and obtained by Fairfax Media, made a rosier assessment of another potential port site near the Werribee treatment ponds, concluding it would have a “low environmental impact”.

The orange-bellied parrot. Credit:Gary Sissons

Labor and the Napthine government are at odds over the best location for Melbourne’s next container port, though both want to build one before the Port of Melbourne hits capacity within the next 10 to 20 years.

Freight movements make up about 8 per cent of Victoria’s economy, but data released on Tuesday shows Melbourne lost ground to Sydney in container movements and ship visits last year, prompting one maritime expert to predict Port Botany could overtake the Port of Melbourne as Australia’s busiest within two years.