The strange noise that has left Tauranga residents puzzled has been confirmed as a bird scarer by the Western Bay of Plenty District Council.

Compliance and monitoring manager Alison Curtis says the council is aware of the concern from some residents and has had about 14 calls from the public over the past 24 hours asking what the noise is.

'The sound is generated by bird scarers of which there are many around the district.

'They are a useful tool for orchardists to scare birds off the buds on kiwifruit orchards.”

From around mid-August to mid-October, orchardists use bird scarers frequently as that is budding time on their orchards.

'Each year council has many calls about the noise and investigates each call.

'Bird scarers are a legitimate horticultural tool and are a permitted activity in the Western Bay with some conditions surrounding their use. They can only be turned on half-an-hour before sunrise and must be turned off half-an-hour after sunset.

'They must also be located within a prescriptive distance from dwellings and boundaries.

'They are permitted to be used 12 times per hour and have a decibel limit of 65dba max. To put this in context, sound's loudness is measured in decibels. Normal conversation is about 65db, a lawn mower is about 90db, and a loud rock concert is about 120db.

'Council's compliance officer has contacted the orchardists believed to be responsible for the calls which refer the noise coming for the direction of Matakana Island.

'We have contacted the orchardist on Rangiwaea Island and have confirmed with him that he is operating his bird scarers within the rules.

'There was one instance when the scarer was mistakenly not turned off at the correct time after sunset. This was remedied quickly before it got too late in the night.

'Our advice to people is that this is part of orcharding practice. The scarers are most likely to reduce in use from mid-October.”