Square birdsong in full cry

‘‘Autumn is more of a problem, especially with the starlings.’’ John Brenkley, Palmerston North City Council property manager

Autumn could be to blame for the increase of flocks of starlings and sparrows returning to Palmerston North’s Square to roost at dusk.

The city council last year spent $50,000 installing bird scarers to ward off the flocks that spend the night splattering the ground beneath, footpaths, roadside and parked cars with their droppings.

But at the end of daylight saving, the hordes had settled in again, undisturbed.

Council property manager John Brenkley said the scarers were turned on, but the volumes and range of noises appropriate for summer needed to be changed with the seasons.

‘‘Autumn is more of a problem, especially with the starlings.

‘‘It’s cooling down, and they want some wind protection, and they get that with the buildings.’’

Brenkley said the birds got used to the scarers unless the noise patterns were altered. Some of that could be done remotely, but the installation contractor had to get up among the branches to change the soundtracks.

He said the challenge was to break the habits of generations of birds.

‘‘We have to provide constant agitation to put them off.’’

Brenkley was more hopeful the bird scarers were having greater effect than a range of earlier interventions, including hanging owls and CDS, and water jets.

Massey University associate professor in ecology and zoology Isabel Castro predicted the scarers would not work, or at least, not for long.

‘‘All I can say is that birds are smart and they learn.’’

Castro said the council would be better spending money hanging sails below the branches to collect the fertiliser.

Brenkley said collecting the bird poo had not been considered.

‘‘Where there are trees over lawn, and they fertilise the grass, that’s fine. It’s just where they drop over footpaths, cars and the road that it’s a problem.’’