Contractors will photograph about 20 significant and heritage listed trees in the park over coming months after the colony's numbers ballooned from an estimated 2000 to 20,000 in recent months.

The council wants to better understand how the trees cope during intermittent surges in flying fox numbers, acting manager of active and healthy lifestyles Paul Gangell said.

"We will be able to understand which trees they (flying foxes) are focusing on, but also how much damage is being caused and what is sustainable," he said.

"Each time (contractors) come in they will do an assessment of the same 'photo points' to get a greater explanation of the tree's growth nodes over the season.

"They will be here once a month doing those assessments."

The council has also increased cleaning rounds to several times a week as they deal with extra guano falling on Rosalind Park's footpaths and bridges.

"Cleaning really just depends on how the bats move through the park, where the pressure points are and the weather conditions, particularly now that we are coming into warmer temperatures," Mr Gangell said.

"We will continue to monitor that weekly over the next few months."

"We are mindful too that we are about to come into our events season at the park."

The next major event at the park is associated with the Bendigo Blues and Roots Festival, which begins next month.

"We understand there are a lot of people who are concerned about high numbers of bats there. Look, we are also concerned," he said.

"But this is a threatened species. It is a marvelous spectacle to see them fly off from the park at night, particularly in this number.

"I know there are a lot of people who come down to view them. So there's a wide variety of views in the community."

The council and the Department of Environment, Land, Water and Planning - which is also monitoring the spiking population - have no plans to purge the park of flying foxes.

"There's no options in terms of getting rid of them. It's not a permissible act and if council ended up going down that path it would require federal approval," Mr Gangell said.

"And in all honesty, it's an expensive exercise. We know the Royal Botanic Gardens Melbourne went through a dispersal program and it cost something into the millions.

"We're certainly not at that point.

"We think we can manage 'peak load events' and we are getting a better understanding about what the impacts of those are."

Related - Fair or foul: how flying foxes could make or break Rosalind Park

The colony's population has swelled periodically, reaching as high as 30,000 in 2017.

"When the numbers do spike we know it doesn't last long," Mr Gangell said.

A combination of factors have led to the latest surge, he said.

"Forests are flowering prolifically at the moment and we've also had a range of events happen interstate, with very dry conditions that have impacted available food sources."

"Once that food lessens we hope they will disperse in number."

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It's unclear where the latest waves of flying foxes had come from, Mr Gangell said.

"We know they do travel up and down the eastern seaboard. They can certainly travel 1500 or 2000km," he said.

"But they are a species we don't fully understand - at least in terms of their migratory patterns."

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