Senior Sergeant Steve Crawford of Central District Police said the incident, coupled with that of a 10-year-old boy near New Plymouth who was shot in the foot, was a "timely reminder" for hunters to follow the rules of firearm safety.
"On occasions when hunters momentarily drop their guard, the consequences can be absolutely tragic," Mr Crawford said.
"All hunters need to stay alert at all times when handling firearms and take extra care in the dark."
Firearms Safety Specialists NZ spokeswoman Nicole McKee was "bitterly disappointed" that the duck hunting season had begun with so many serious incidents.
"Safety messaging is being pushed to all shooters before and during the season, but not everyone is taking heed of the warnings."
She said bird shooting carried the added risk of a moving firing zone.
"There is risk that other hunters and their dogs may venture into that zone. Take a look at what's around you before you pull the trigger."
The law requires unlicensed firearms users to be under "direct supervision" from a licence holder, she added. "That means being within arms-length of that person while they use a firearm. Arms-length allows the experienced firearms user to take control of the shotgun should a dangerous situation arise, like pointing the firearm in an unsafe direction."
After some reports of homes being peppered by stray shots, Ms McKee cautioned hunters to ensure they had the land owner's permission to hunt on their land.
In new areas, shooters should be aware of homes and stock.
