Brown Kiwi

All brown kiwi livei n the North Island. Four geographically and genetically distinct forms have been identified: Northland, Coromandel, western and eastern brown kiwi.

Population Status

Brown kiwi is the second most numerous kiwi species (after tokoeka), with a total population of about 25,000. However, because populations are declining rapidly, it is classified by the Department of Conservation as  ‘threatened: nationally vulnerable’, and its future depends on active management.

Most of the many community-led kiwi conservation groups in the North Island focus on helping brown kiwi, and their efforts are making an enormous positive difference to the birds’ future.

Within brown kiwi, the Coromandel variety is the most rare, with about 1000 birds. However, the population is growing thanks to the Moehau kiwi sanctuary and the many community-led kiwi initiatives in the northern Coromandel. Numbers for the other three brown kiwi taxa are similar to each other, but dropping because many birds live in places with little or no management. Where they are actively managed, populations are flourishing.

The table below shows the estimated brown kiwi populations in 2008, and what they could be in 10 years time, assuming that unmanaged mainland populations decline by 4% each year, island populations are stable, and managed populations increase by about 7% each year.

Family dynamics

Breeding Pairs

As with other kiwi species brown kiwi pairs are generally monogamous—that is, they have only one mate at a time. Monitoring shows that fewer than 5% of eggs don’t belong to both parents.

Brown kiwi also generally mate for life. Divorces do sometimes happen, usually after failed breeding attempts or if the birds are early in their breeding career. One couple, known as Liz Taylor and Richard Burton, divorced and then came back together. Research suggests that birds that divorce once are more likely to divorce again.

Eggs and Clutches

Brown kiwi usually have two eggs in each clutch. While just one egg is not unusual, three is very rare.

 Pairs usually have two clutches a season, which means that in a good year they can raise four chicks. Some pairs have just one clutch. Some pairs will lay more than two clutches if their eggs are removed as part of Operation Nest Egg or if lost to predation early on.

Incubation

Only the male brown kiwi incubates the eggs. He loses about 20% of his body weight during this time.

Chicks

Brown kiwi chicks are never fed by their parents. They first leave the burrow to feed when 5–7 days old—up until then they are nourished by the large yolk sac, leftover from when they were in the egg. Brown kiwi chicks leave the nest fend for themselves from about 10 days of age, though some return to the nest for up to 60 days. Most finally leave their parents’ nest when about 20 days old.

While the mother stays near the nest while hatching is in progress, only the male parent stays around the young chick when it returns to the burrow each day, to share warmth and maybe protection.

Operation Nest Egg

Brown kiwi have been part of Operation Nest Egg since the tool’s earliest days, beginning in 1993. The tool is now used on all four taxa, with the Coromandel brown kiwi the latest addition.

Research has shown that when eggs are taken, adult brown kiwi lay 30% more eggs over a season. However, if a newly-hatched chick is taken the parents are less likely to lay another clutch. That means taking eggs rather than newly-hatched chicks boosts kiwi populations more quickly as the adult birds are more likely to re-lay.

Monitoring has revealed no evidence that Operation Nest Egg increases the likelihood of divorce—there had been a concern that pairs may have treated the eggs’ disappearance as breeding failure, which can cause divorce.

Kohanga kiwi

Several kohanga kiwi populations exist or are planned for brown kiwi. You can read about them here. 

Preferred habitat

Brown kiwi seem to prefer lowland and coastal native forest - their population density is highest in these areas. However, they are also found in sub-alpine areas - at the Chateau in Tongariro National Park, and near the bushline at Taranaki. Huge changes to New Zealand’s original forest cover mean they have had to be adaptable.

Today brown kiwi live in many different types of vegetation, including exotic forest plantations and rough farmland. While this may seem surprising, plants growing under Pinus radiata trees often support native species, which means the soils provide an ample supply of insects for kiwi to eat.