Despite that, the average lifespan of kiwis in the area is about 15 years, compared to 40 to 60 years in other parts of New Zealand.
Don Robertson, DOC's acting kiwi programme manager for Whangarei, said 80 per cent of adult kiwis deaths were caused by pet dogs every year - including 30 in Whangarei alone.
He said kiwis made an ideal target for dogs because they were "nice smelling" and would run away when disturbed.
Dog owners needed to take responsibility for keeping their pets on a lead, he said.
"People believe they just have the right to keep their dogs off the lead - or they say 'my dog wouldn't do that'. Of course it would. People don't understand kiwi can be half a metre off the track sheltering under a bush.
"It is very devastating toll. It is significant."
Kiwis' lack of a breastbone meant any bite from any dog - small or large - could be fatal, Mr Robertson said.
"Any dog can kill a kiwi. It only takes the smallest nudge or crush to its chest.
"Farm dogs are generally under control. Hunting dogs, generally under control. It's the little yappy ones that are just that - little, yappy and often out of control... They can kill kiwi."
In 2008, the population of Northland brown kiwi was calculated at around 8000 birds, living in 25 clusters from Tawharanui to Whakaangi.
It is estimated that the number of North Island kiwi declined by at least 90 per cent during the 20th century.
By Hayden Donnell | Email Hayden
