Mainland populations of this species may be decreasing extremely rapidly, based on annual declines, predation and loss of habitat. However, owing to the stability of island populations, and intensive predator control in select mainland populations, the overall decline is likely to be slower, but still very rapid, thus warranting Endangered status.
Baker, A. J.; Daugherty, C. H.; Colbourne, R.; McLennan, J. L. 1995. Flightless Brown Kiwis of New Zealand possess extremely subdivided population structure and cryptic species like small mammals. Proceedings of the National Academy of Sciences of the
Apteryx australis (Sibley and Monroe 1990, 1993) has been split into A. australis and A. mantelli following Baker et al. (1995).
Distribution and populationApteryx mantelli
40 cm. Medium-sized kiwi, flightless, no visible wings. Dark greyish-brown feathers streaked lengthways with reddish-brown. Long ivory bill. Similar spp. Okarito birds distinguished from Tokoeka A. australis by slightly greyer plumage, occasional white facial whiskers. Voice Shrill, clear ascending then descending whistle (male), lower-pitched, hoarse cry (female). Note duration and inter-note interval increase during a calling bout, and there is evidence that the species may duet (Corfield et al. 2008). Hints Loud calls at night, especially first two hours of darkness.
was once widespread throughout the North Islands and northern South Islands of New Zealand
. Remaining populations are isolated and fragmented. Birds are locally common in Northland, and mostly sparsely distributed in the Coromandel Peninsula, Bay of Plenty, Gisborne to the northern Ruahine Range, and from Tongariro to Taranaki. Stable populations are present on Little Barrier (c.1,000 birds), Kawau and Pounui Islands (Heather and Robertson 1997, H. A. Robertson in litt.
1999). Hybrids are present on Kapiti Island (H. A. Robertson in litt.
1999). The total population was estimated at 25,300 birds in 2008 (Holzapfel et al.
2008), down from an estimated 35,000 (± c.25%) birds in 1996 (Robertson 2003). Numbers have probably declined by at least 90% since 1900, and are declining at 2.5% per annum in unmanaged mainland populations (Robertson et al.
2011). The previously estimated decline of 5.8% per annum (McLennan et al.
1996) is now thought to have been too pessimistic and based on a small sample size subject to several acute mortality events (Robertson et al.
2011). The total A. australis '
Okarito' population is thought to be 300 individuals (Holzapfel et al.
2008) restricted to 10,000 ha of coastal podocarp-hardwood forest between the Okarito River and the Waiho River (Tennyson et al.
2003). Population justification
In 1996, the total population was estimated to number 35,000 individuals. Holzapfel et al.
(2008) estimated a total population of 8,000 individuals in the Northland population, 1,000 in the Coromandel population, and 8,000 in both the western and eastern North Island populations in 2008. Colbourne et al.
(2005) reported that the Okarito population was at a minimum of c.160 individuals in 1995 and had increased to c.200 by 2000. It was estimated to have increased further to 300 individuals by 2008. The total population estimate is precautionarily retained as 35,000 individuals until these data are confirmed.Trend justification
Unmanaged populations are declining at 2.5% per annum owing to introduced predators, which would result in a halving of the population every 27 years (Robertson et al.
2011). The previously estimated decline of 5.8% per annum (McLennan et al.
is now thought to have been too pessimistic and based on a small sample size subject to several acute mortality events (Robertson et al.
2011). Adult mortality was 7.3% per annum and life expectancy is greatly below the expected value at 13.8 years vs. approximately 40 years (Robertson et al.
2010). Populations for which intensive conservation programmes are in place are stable or increasing (Holzapfel et al.
2008), with the Okarito population increasing from c. 160 to c. 200 between 1995 and 2000 (Colbourne et al.
2005). Overall, the species is estimated to be in very rapid decline.Ecology
It favours dense, subtropical and temperate forests, but is also found in shrublands, scrub, regenerating forest, exotic pine plantations and pasture (Marchant and Higgins 1990). Diet
Invertebrates are the primary food (Heather and Robertson 1997). Breeding
Clutch size is one or two (with single clutches more frequent in high-density populations [Ziesemann et al.
2011]) and there are up to three clutches in a year (Colbourne 2002, Ziesemann et al.
2011). The male carries out almost all of the incubation (Colbourne 2002), which is amongst the longest for any bird at between 74 and 84 days (Calder et al.
1978). Laying was recorded in every month between June and November in a high-density population in 2007 (Ziesemann et al.
2011). Chicks hatch fully-feathered, and first leave the nest unaccompanied after about a week. It is long-lived, with generation time taken to be 10-15 years (H. A. Robertson in litt.
1999). More chicks were found to hatch in reused nests than in previously unused burrows (Ziesemann et al.
The most significant threat to the survival of the species is predation of adults by dogs and ferrets Mustela furo
with predation of young kiwi by Stoat Mustela erminea
and cats also affecting populations
(McLennan et al.
1996, Basse et al.
1999, Holzapfel et al.
2008, Robertson 2010). Significant spikes of mortality can occur, for example, a single dog killed c.500 birds in six weeks (Taborsky 1988), and over 70 incidents of dogs killing kiwi in Northland occurred between 1990 and 1995 (Pierce and Sporle 1997). The smaller male kiwi may be at greater risk of predation by ferrets, resulting in a skewed sex ratio and reduced effective population size (Robertson 2010). In one population prior to management at least 94% of chicks died before reaching breeding age (McLennan et al.
1996). About half were killed by introduced predators, in particular, stoat Mustela erminea
and cats (McLennan et al.
1996). Juvenile kiwi become too large for stoats above about 800g, which takes about four months to achieve (McLennan et al.
2004). The clearance of habitat fragments continues to threaten small populations (Hutching 1995, Miller and Pierce 1995), but the rate of loss of native habitat has declined markedly and this is not currently considered a driver for population reductions (Robertson 2010). New avian diseases and pathogens are a potential threat, particularly with the importation of non-native but closely related ratites to New Zealand (Holzapfel et al.
2008). The Okarito population is at risk from stochastic events due to its small size and isolation and suffers from low fecundity (Holzapfel et al.
2008). No recruitment was observed from 12 breeding attempts monitored in this population prior to any management intervention (Colbourne 2002). Conservation Actions Underway
Monitoring is intensive and nationally coordinated, and uses call-counts, specially-trained dogs searching for banded birds, and radio-tracking (Robertson et al.
2010). Key populations are managed by controlling predators by the use of trapping and poisoned baits (Robertson 1998), with leg-hold predator traps are raised above the ground to prevent accidental trapping (H. A. Robertson in litt.
1999). Kiwi aversion training for hunters' dogs is being trialled, although there is no evidence that this is a viable long-term solution (Robertson et al.
2010). A programme of removing and incubating eggs and returning subadults once these are large enough to fend off predators has been developed since 1995 under the name Operation Nest Egg (ONE, or BNZONE as the funding has been provided by the Bank of New Zealand) (Colbourne et al.
2005, Pickard 2009, Robertson et al.
2010). A dedicated rearing facility was constructed at which 942 eggs received from the wild produced 475 young released back into the wild between 1995 and 2008 (Pickard 2009), with survival in captivity greatly improving during this time (Colbourne et al.
2005, Pickard 2009). BNZONE has been demonstrated to be the most effective tool for the species, resulting in a 12.5% annual population increase within managed sites, due to 83% chick survival (Robertson et al.
2010). Due to the cost and need to locate nests this approach is only practical within areas up to 10,000 ha and should be used to turn around declines in the most threatened and restricted populations and subspecies (Colbourne et al.
2005). Many national and overseas captive populations are held (Heather and Robertson 1997). Conservation Actions Proposed
Carry out landscape-scale pest control at sufficient intervals at the sites that are currently unmanaged, specifically for mustelids, rats, cats and dogs (Holzapfel et al.
2008). Clarify the taxonomy of the Okarito population. Conduct research into reasons for low productivity in the Okarito population. Evaluate islands for possible translocation of Okarito birds. Intensively manage the Okarito population, and at least one population of each regional taxon using the BNZONE programme to increase the population size (Holzapfel et al.
2008). Consider establishing a further population of Okarito birds in North Okarito Forest (B. Weeber in litt.
2000). Undertake population modelling for all taxa. Investigate landscape-scale remote monitoring techniques for sparse populations (Holzapfel et al.
2008). Promote legislative and policy changes to protect populations and encourage high-quality advocacy at all levels (Robertson 1998, Holzapfel et al.
2008). Educate and inform the public and encourage community involvement in Kiwi conservation (Robertson 1998, Holzapfel et al.
Baker, A. J.; Daugherty, C. H.; Colbourne, R.; McLennan, J. L. 1995. Flightless Brown Kiwis of New Zealand possess extremely subdivided population structure and cryptic species like small mammals. Proceedings of the National Academy of Sciences of the United States of America 92: 8254-8258.
Basse, B., McLennan, J.A. and Wake, G.C. 1999. Analysis of the impact of stoats, Mustela erminea, on the northern brown kiwi, Apteryx mantelli, in New Zealand. Journal of Wildlife Research 26: 227-237.
Calder, W.A., Parr, C.R. and Karl, D.P. 1978. Energy content of eggs of Brown Kiwi Apteryx australis-extreme in avian evolution. Comparative Biochemistry and Physiology 60(2): 177-179.
Colbourne, R. 2002. Incubation behaviour and egg physiology of kiwi (Apteryx spp.) in natural habitats. New Zealand Journal of Ecology 26(2): 129-138.
Colbourne, R., Bassett, S., Billing, A., McCormack, H., McLennan, J., Nelson, A. and Robertson, H. 2005. The development of Operation Nest Egg as a tool in the conservation management of kiwi. Department of Conservation, Wellington.
Corfield, J.; Gillman, L.; Parsons, S. 2008. Vocalizations of the North Island Brown Kiwi (Apteryx mantelli). The Auk 125(2): 326-335.
Heather, B. D.; Robertson, H. A. 1997. The field guide to the birds of New Zealand. Oxford University Press, Oxford, UK.
Holzapfel, S.; Robertson, H.A.; McLennan, J.A.; Sporle, W.; Hackwell, K.; Impey, M. 2008 . Kiwi (Apteryx spp.) recovery plan: 2008â€“2018. Department of Conservation, Wellington.
Hutching, G. 1995. Kiwi recovery? Attempting to save a national icon. Forest and Bird 278: 22-28.
Marchant, S.; Higgins, P. J. 1990. Handbook of Australian, New Zealand and Antarctic birds, 1: ratites to ducks. Oxford University Press, Melbourne.
McLennan, J. A.; Potter, M. A.; Robertson, H. A.; Wake, G. C.; Colbourne, R.; Dew, L.; Joyce, L.; McCann, A. J.; Miles, J.; Miller, P. J.; Reid, J. 1996. Role of predation in the decline of kiwi, Apteryx spp., in New Zealand. New Zealand Journal of Ecology 20: 27-35.
McLennan, J.A., Dew, L., Miles, J., Gillingham, N. and Waiwai, R. 2004. Size matters: predation risk and juvenile growth in North Island Brown Kiwi (Apteryx mantelli). New Zealand Journal of Ecology 28(2): 241-250.
Miller, P. J.; Pierce, R. J. 1995. Distribution and decline of the North Island Brown Kiwi (Apteryx australis mantelli) in Northland. Notornis 42: 203-211.
Pickard, J. G. 2009. The National Kiwi Trust - Kiwi encounter. International Zoo News 56(7): 388-400.
Pierce, R.J. and Sporle, W. 1997. Causes of kiwi mortality in Northland. Conservation Advisory Notes 169. Department of Conservation, Wellington.
Robertson, H. A. 1998. Kiwi recovery plan 1996--2006. Department of Conservation, Wellington.
Robertson, H.A., Colbourne, R.A., Graham, P.J., Miller, P.J. and Pierce, R.J. 2010. Experimental management of Brown Kiwi Apteryx mantelli in central Northland, New Zealand. Bird Conservation International.
Taborsky, M. 1988. Kiwis and dog predation: observations in Waitangi State Forest. Notornis 35: 197-202.
Tennyson, A. J. D., Palma, R. L.; Robertson, H. A.; Worthy, T. H.; Gill, B. J. 2003. A new species of kiwi (Aves, Apterygiformes) from Okarito, New Zealand. Records of the Auckland Museum 40: 55-64.
Ziesemann, B.; Brunton. D. H.; Castro, I. C. 2011. Nesting success and breeding ecology in a high-density population of Brown Kiwi (Apteryx mantelli). Emu 111(2): 148-154.
Further web sources of information
New Zealand Govt - Dept of Conservation - Recovery Plan
Text account compilers
Benstead, P., Mahood, S., Martin, R, McClellan, R., Taylor, J.
Robertson, H., Weeber, B.
IUCN Red List evaluators
Butchart, S., Symes, A.
BirdLife International (2014) Species factsheet: Apteryx mantelli. Downloaded from
http://www.birdlife.org on 14/03/2014.
Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from
http://www.birdlife.org on 14/03/2014.
This information is based upon, and updates, the information published in BirdLife International (2000)
Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004)
Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.
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Additional resources for this species