A collection of trained birds of prey has begun nightly patrols of downtown Macquarie Street, which feral starlings in their masses have made their own each autumn.

With weight of numbers on their side the pest species has roosted and wreaked havoc for a decade, leaving a foul mess that costs the city to clean up.

The arrival of the raptors this week marks the continuation of a trial of falconry Dubbo City Council is pursuing as a possible solution after water cannons, lasers and hallucinogenic drugs failed in previous years.

It's a non-lethal control measure - but no one is telling the starlings.

Victorian-based contractor Full Flight Birds of Prey has returned to Dubbo to continue the trial it began in 2014 - and this time Tilley the brown goshawk is part of the contingent that also includes owls and a peregrine falcon.

"What we're doing in Macquarie Street basically is just flying her around, so no lethal methods here, no hunting, no chasing or anything like that," raptor trainer Amber Michalak said.

"In the wild, usually brown goshawks would actually hunt upon starlings but she doesn't hunt, she just flies around and looks scary and we're hoping that's enough to chase them off."

By Wednesday Full Flight Birds of Prey had done two nights of work in Macquarie Street.

"So far we're seeing some pretty good results but we'll see what's to come," Ms Michalak said.

". . . So we're still trying to figure out the little adjustments we need but she (Tilley) has been really effective so far.

"You can definitely tell that the starlings are not happy with her around."

Council landcare services manager Lynton Auld said they had noticed a dramatic decrease in the numbers of starlings in the main street after the contractor's visit in 2014.

"We're still assessing the effectiveness of the trial but so far the signs are good," he said.

Starlings in the CBD were a concern from the perspectives of public health, retail and council clean-up costs, the manager said.

He said Macquarie Street was a "high profile area" and while they knew they would not eradicate the starlings, if they moved to a less high profile area like Victoria Park, it would minimise the risk.

The current starling control program would continue to Sunday (6 March) and there were no disruptions to traffic, the landcare services manager advised.

Mr Auld said while the contractors were in Dubbo, the council had also arranged a number of school visits to help educate local children about birds of prey and their feeding habits, nesting and flying abilities.