conservation of the north island brown kiwi (apteryx mantelli
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Conservation of the North Island Brown Kiwi (Apteryx mantelli):
current approaches, the successes and limitations, and proposals to
ensure long term continuity.
Jack Keast, Tara Kelly, Hayden Moorhouse, Jonathan Tan, & Shih-Yun Wei (2010)
School of Biological Sciences
Victoria University of Wellington, Wellington 6012, New Zealand
The kiwi (Apteryx spp.) is from an ancient lineage that has come to be uniquely and
evolutionary distinct. Endemic to New Zealand, its numbers have steadily declined since
the arrival of the first human inhabitants into the country. In the mid 1990s, a new
conservation approach, comprised of Operation Nest Egg and crching, was initiated by
the Department of Conservation in an attempt to reverse the population decline, by
artificially incubating kiwi eggs and releasing the chicks into controlled predator-free
environments where they can be monitored. Three of these key sites, at varying levels of
predator presence, were reviewed: (1) Cape Kidnappers and Ocean Beach Wildlife
Preserve, (2) Boundary Stream Mainland Island, and (3) Opouahi Pan Pac Kiwi Crche;
that focuses on recovery of the North Island brown kiwi (A. mantelli). However,
assessments showed that the kiwi populations at these sites are at risk of inbreeding
depressions and are potentially of mixed genetic makeup. Moreover, population
viability is jeopardised due to natural dispersal and movement inhibitions, calling for
continued monitoring and human intervention that involves increasing costs. A review
of current local approaches and potential to learn from international initiatives should
be undertaken to guarantee the long-term prospects of kiwi conservation.
North Island brown kiwi, taxonomy, conservation, Cape Kidnappers, Boundary Stream,
Opouahi crche, population viability, genetic management.
1.1 Objectives 5
1.2 Background 5
1.2.1 Kiwi Taxonomy 6
1.2.2 Kiwi Biology and Ecology 8
1.2.3 Plights of the Kiwi 9
1.3 History of Kiwi Conservation 11
1.4 BNZ Operation Nest Egg and Kiwi Crche 12
2.1 Methods Employed 14
2.2 Advantages 15
2.3 Disadvantages 15
2.4 Limitations 15
3.0 FOCUS SITES
3.1 Cape Kidnappers and Ocean Beach Wildlife Preserve 16
3.1.1 Layout and Initial Setup 16
3.1.2 Return of the Kiwi 17
3.1.3 Funding and Costs 18
3.2 Boundary Stream Mainland Island 18
3.2.1 Past and Current Management 18
3.2.2 Predator Control 19
3.2.3 Reintroductions of the Kiwi 20
3.3 Opouahi Pan Pac Kiwi Crche 20
4.1 Population Dynamics and Viability 23
4.1.1 Predation Risks 23
4.1.2 Reserve Size and Habitat Fragmentation 24
4.2 Phylogenetic Variation and Management 26
4.3 Cost Effectiveness 29
4.4 International vs. Local Conservation Approaches 30
5.0 RECOMMENDATIONS 33
This report has been prepared in an effort to contribute to the overall conservation
practices currently in place for New Zealands iconic national bird, specifically the North
Island Brown Kiwi (Apteryx mantelli), by aiming to:
Establish an insight into the issues and concerns affecting kiwi management,
including their biology, behaviour and conservation history.
Define and analyse the current procedures of the Bank of New Zealand (BNZ)
Operation Nest Egg (ONE) and kiwi crche, sanctioned by the Department of
Identify the current North Island brown kiwi population dynamics within three
key sites in the Hawkes Bay region of New Zealand.
Provide an assessment on the success of these key sites in kiwi conservation and
breeding through an analysis of the population viability, genetic management
and cost effectiveness.
Examine current local initiatives for kiwi in comparison to international efforts
involving other endangered species.
Explore recommendations and improvements to future kiwi conservation
Endemic to New Zealand, the kiwi is known to have evolved around 65 million years
ago (Holzapfel, et al., 2008). Before the arrival of humans in the 13th century, kiwi
populations were more widespread (DOC, 2004) and could have been as high as 12
million birds. Today, the total kiwi population is estimated to be only circa 80,000 birds.
All taxa are at risk, with some more so than others (BirdLife International, 2008). Also,
given their rarity, very few New Zealanders have ever seen one in the wild (Peat, 2006).
1.2.1 Kiwi Taxonomy
Initially, there were only three species of kiwi; the brown, the great spotted and little
spotted. Over the past two decades, the introduction and use of genetic and biological
data in the early 1990s was a major breakthrough in kiwi species classification,
especially in the revision of brown kiwi phylogeny. Genetic analysis has resulted in the
current identification of five formally recognised species, with 4 geographically and
genetically distinct races distinguished within two of these species (Sales, 2005)
(Holzapfel, et al., 2008).
Species: North Island Brown Kiwi Apteryx mantelli
Okarito Brown Kiwi/Rowi Apteryx rowi
Southern Tokoeka Apteryx australis
Great Spotted Kiwi Apteryx haastii
Little Spotted Kiwi Apteryx owenii
The North Island brown kiwi is further split into the following races: the Northland;
Coromandel; Eastern; and Western populations. Additionally, four races of the Southern
tokoeka are also recognised: the Haast; Stewart Island; Northern Fiordland; and
Southern Fiordland populations (DOC, 2004). However, ongoing genetic analysis
continues to confirm these classifications. As such, the uniqueness in the Haast
population of the Southern tokoeka is still awaiting formal description, and may be
elevated to species distinction (BirdLife International, 2008).
Figure 1. Map showing the current distribution of the various kiwi species in New
Zealand. Also featured are 5 kiwi sanctuaries set up on mainland New Zealand during
2000. Each sanctuary focuses on a specific kiwi taxon: Whangarei on the Northland
North Island brown kiwi, Moehau on the Coromandel North Island brown kiwi,
Tongariro Forest on the Western North Island brown kiwi, South Okarito Forest on the
Okarito rowi, and Haast Range on the Haast tokoeka (BNZ Save the Kiwi Trust, 2011).
1.2.2 Kiwi Biology and Ecology
The kiwi has tiny vestigial wings and no external tail (Holzapfel, et al., 2008). The birds
have a slow metabolic rate and low body temperature, which are both adaptations to
enhance energy conservation, and most likely motivated flightlessness. Dimorphism
also occurs with females generally being larger than males (Sales, 2005).
The kiwi has a highly developed sense of smell. Their bills are highly efficient at probing
for food and have specialised pressure sensing nerve endings, which help in detecting
vibrations of invertebrate in the soil (Sales, 2005). There is also evidence that kiwi
sometimes feed in rivers and streams, often indulging in freshwater crustaceans like
koura, highlighting kiwis ability to swim (Peat, 2006).
Largely nocturnal, the birds leave their burrows at dusk to forage for food (Holzapfel, et
al., 2008). However, there is evidence of Stewart Island kiwi foraging in the day, due to
several factors. For example, females incubate their eggs at night, low concentrations of
food, and/or short summer nights on the island, resulting in only five hours of darkness
during mid-summer (Peat, 2006).
Kiwi pair bonds are usually long term. Highly territorial, the paired birds employ
olfactory signals to mark territories and use far-carrying shrill and guttural calls to
communicate with each other when out foraging (McLennan, 1988) (Sales, 2005). When
not foraging, kiwi shelter and nest in burrows, hollow logs or under dense vegetation
(Holzapfel, et al., 2008). These burrows can be found all over a kiwis territory, with
some species having several entry points and others just having one (Peat, 2006).
Egg laying and incubation behaviour varies among the different species (Colbourne,
2002) (DOC, 2004). Kiwi eggs are one of the largest eggs relative to body weight of all
birds (Bassett, McLennan, & Blackwell, 2005). Female kiwi usually laid two egg clutches,
due to having two functioning ovaries, but the rarest species often lay only one egg
(Peat, 2006). In some species, the male undertakes the entire incubation process, a
period of up to two and a half months (S