New Zealand, a land of birds, had no land based mammalian predators before people introduced them. These are now the main threat to kiwi’s survival – killing chicks and adults.
Stoats are public enemy number one for kiwi chicks and are the main reason why 95% of kiwi hatched in the wild die before they reach breeding age.
For adult kiwi the biggest threat they face are dogs, wandering dogs killing kiwi is the reason why in Northland kiwi only live on average to 14 years old. Kiwi can live till they are 60 if they are kept safe from predators. The largest Mustelid in New Zealand the ferret can devastate a kiwi population. In Tongariro 56 monitored kiwi were killed by ferrets over the course of a decade. The loss of adult kiwi is especially difficult because those are the breeding birds – without them there are no eggs or chicks to keep the population stable or growing.
Other animal pests, such as cats, pigs, possums hedgehogs, rodents and weasels, may not kill kiwi, but they also cause problems. Whether they compete for food, habitat or, they are prey for the same animals that attack kiwi, helping to keep the number of predators high.
Turning the tide
In areas where kiwi predators are intensively controlled, kiwi hatching increases to 50 – 60%. In order to sustain populations levels a 20% survival rate is needed, anything over that it grows. So management is making a difference, especially when dog owners keep their dogs under control.
Find out how Kiwis for kiwi are helping dog owners care for kiwi.