Council said there are reports of "substantially lower" numbers of starlings in the main street this March but it is "too early to tell" if it's permanent and if a falconry trial last year is the cause.

It provided the advice on Wednesday as it confirmed raptors were set to return to Dubbo for a second week charged with the task of scaring off the feral birds.

While the council is not yet claiming victory, it is "watching closely" the effect of what it says is a "unique" control measure.

Starlings that have roosted in the centre of Dubbo each evening in the late summer and autumn period, leaving faeces on the street, cars and anything else below, have been a costly headache for a decade.

Water cannons, laser lights, hallucinogenic drugs and other control measures all failed to permanently budge the starlings from the comforts they found in Macquarie Street.

The council resolved to undertake a two-week falconry trial last year, a recommendation from a special Charles Sturt University (CSU) study, with a contractor carrying out the first of the two-week trial in late April.

The cost of the two-week trial, which involved the raptors flying around but not striking the starlings, was last year estimated at $18,000.

Reports from staff were there were "substantially lower" numbers of starlings in Macquarie Street as there had been historically in March, council landcare services manager Lynton Auld said on Wednesday.

"We're not sure if they have moved permanently or if it's the warm weather keeping them away," he said.

"We're watching closely, it could be indicative last year's trial had an impact or it could be climatic.

"It's too early to tell, that's why we're having a second trial week of the falconry."

Mr Auld said the "microclimate" of Macquarie Street had in the past attracted the starlings.

He said the council had treated the problem scientifically, engaging CSU to conduct studies and then acting on their recommendations.

"We're doing something unique here in Dubbo, trying to eliminate the variables to see if falconry does have the effect of reducing starling numbers in a specific location."

The manager said he was yet to have a date for the arrival of the raptors and their owner.

The Victorian-based contractor, which has flown wedge-tailed eagles at the Melbourne Cricket Ground to scare away troublesome pigeons, was obtaining a permit to enter NSW, Mr Auld said.

He said they hoped the trial could be conducted earlier than it was last year.