Hordes of highly aggressive feral geese are roaming Western Springs, harassing the public and defecating in enormous quantities.

Numbers have exploded due to overfeeding from the public, and Birds New Zealand (BNZ) is calling for a ban on the public feeding the birds - and a cull if necessary.

"Bread should never be fed to birds. It is completely unnatural and is absolute junk food for them," BNZ Auckland regional representative Ian McLean says.

"Feeding the birds changes their natural behaviours and makes them aggressive to both people and other birds.

"At Western Springs, people often park their cars on Great North Road only to be met (and harassed) by geese whilst only 10 or so metres from the road. This is because the geese are often fed by families with loaves of white bread in this area."

It's not just the geese causing problems. Ducks, pukekos, gulls and feral pigeons are also causing issues with their behaviour.

"Mallard ducks [are] highly invasive, a sexual predator and a threat to many types of native and endemic waterfowl," McLean says.

"Pukeko [are] a predator of the chicks and eggs of many birds. One of their favourite foods is ducklings and at Western Springs only the more aquatic young of scaup ducks and Australasian coots generally survive."

As a consequence of the frequent feeding, the birds create a "huge amount" of poo, which creates serious health hazards both for humans and other animals.

"The unnaturally high level of bird droppings foul the footpath, grass, and combined with rotting bread pollute the water by enriching it with nutrients," McLean says.

"The nutrification of the water contributes to botulism (caused by a soil bacteria) in the warmer summer months.

"The botulism kills many types of birds, and volunteers then spend countless hours taking sick birds to rescue centres and collecting dead birds out of the water."

McLean wants Auckland Council to ban the feeding of birds at Western Springs, both on the grass and in the water.

He also says that if enough geese can't be relocated to private owners, BNZ supports the necessary culling of the birds.

Auckland Council says it undertakes nest management during breeding season to limit the number of birds, but despite this geese numbers have "significantly increased".

"We are currently investigating methods to reduce the number of birds at Western Springs," say head of operational management and maintenance Agnes McCormack.

"We discourage feeding birds at Western Springs, as it is detrimental to them and affects water quality which can lead to avian botulism in warmer months. We have signage around the water's edge at Western Springs advising visitors not to feed the birds."

Newshub.