A city in northern Lithuania has installed dozens of blue and violet balloons in its park's treetops in an attempt to fight crows which have plagued local residents, officials said Thursday.

Municipal authorities in Panevezys said they reacted after repeated complaints about the birds' raucous cawing, mess and even aggression in the city park.

"I heard from scientists that crows don't like the colour blue, and they also don't like any movement in the trees, so we installed around 25 balloons," city official Antanas Karalevicius told AFP.

Earlier measures -- including destroying nests and installing a bird-scaring acoustic system -- failed to do the try.

"We had to try something new," Karalevicius said.

Locals said battling the crows was a must.

"Their cawing is just terrible and they pollute so much. I think balloons are better than shooting," Andrius Zimaitis, who hails from the city, told AFP in the Lithuanian capital Vilnius.

While the effect of the new weapon remains to be seen, Karalevicius insisted he had already noticed some "confusion" among crows on the first day of the experiment.

The helium-filled balloons should stay floating in the trees for at least 10 days, he said.