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Puffinus huttoni

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA AVES PROCELLARIIFORMES PROCELLARIIDAE

Scientific Name: Puffinus huttoni
Species Authority: Mathews, 1912
Common Name(s):
English Hutton's Shearwater

Assessment Information [top]

Red List Category & Criteria: Endangered B2ab(ii,iii) ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Cuthbert, R.
Facilitator/Compiler(s): Anderson, O., Benstead, P., Calvert, R., Mahood, S., Martin, R, McClellan, R., Stattersfield, A. & Taylor, J.
Justification:
Although this species has a stable population, habitat changes are still occurring through continued, although much reduced, erosion and vegetation regeneration as a result of herbivore control. It qualifies as Endangered because breeding is restricted to just two colonies which may be losing burrows.

Geographic Range [top]

Range Description: Puffinus huttoni breeds in the Seaward Kaikoura Range, north-east South Island, New Zealand. The population comprises two main colonies (Kowhai Valley and Shearwater Stream), sited 10-18 km inland. These were estimated to consist of c.125,000 and c.10,000 pairs (Sherley 1992), but reworking of the original data indicated c.94,000 pairs is more accurate (Taylor 2000). More recently Sommer et al. (2009) reported 106,000 pairs at Kowhai and 8,000 pairs at Shearwater Stream. The total population is estimated to number 300,000-350,000 individuals (Brooke 2004). Numbers and distribution within the Kaikoura Ranges have decreased, with 8 of 10 known colonies having been extirpated this century (Cuthbert 1999). Six out of eight colonies discovered in the high Kaikoura mountains were extirpated by pigs, and feral pigs remain a potential threat the remaining two colonies (Harrow 2009). Since the rapid extirpation of colonies was detected, work has been underway to establish a third population on the Kaikoura peninsula through the translocation of 290 chicks (Anon 2007, Ombler 2010), and predator-proof fencing was introduced in 2010. Individuals have been returning since 2008 (Ombler 2010). For many years this species has been considered to be in a long-term decline (Sherley 1992, Heather and Robertson 1997), but a major study has indicated that the population was stable from at least 1990-2000 (Taylor 2000). Recent evidence even points to a long-term increase in the population for the Kowhai Valley, at an annual rate of 1.7% over the last 20 years, based on burrow density (Sommer et al. 2009). In the non-breeding season birds migrate to waters off southern, western and north-western Australia (Heather and Robertson 1997).

Countries:
Native:
Australia; New Zealand
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Cuthbert and Davis (2002) estimated 106,000 breeding pairs, and Brooke (2004) estimated a total population of 300,000-350,000 individuals.
Population Trend: Stable

Habitat and Ecology [top]

Habitat and Ecology: It digs its burrows on gentle to steep mountain slopes at 1,200-1,800 m, under tussock grass or low alpine scrubland (Marchant and Higgins 1990). First breeding is thought to occur at 4-6 years of age. It feeds mostly on small fish and krill (Heather and Robertson 1997). Birds gather food for chicks as far south as the Otago Peninsula and often fish around Banks Peninsula bays (Harrow 2009). Kapiti Island and Cook Strait are common feeding areas in the north and they have been recorded near the Chatham Islands (Harrow 2009). Frequently diving to feed at c.25 m, they have been recorded as deep as 36.6 m (Harrow 2009). Burrow occupancy levels in both original colonies in 2006/2007 was found to be similar to the 1990s. In contrast, breeding success in both main colonies was thought to be due to poor at-sea feeding conditions, rather than increases in stoat predation, due to a lack of evidence pointing to the latter (Sommer et al. 2009). Annual adult survival, breeding success, and burrow occupancy averaged 93%, 47% and 71%, respectively (Sommer et al. 2009). Low levels of breeding success, particularly at Shearwater Stream colony, point to the possibility of the colony levels being maintained by immigration from the more successful Kowhai Valley colony (Sommer et al. 2009).

Systems: Terrestrial; Marine

Threats [top]

Major Threat(s): Introduced stoats Mustela erminea were thought to be the primary cause of decline (Sherley 1992, Heather and Robertson 1997). Long-term research, however, has indicated that only a very small proportion of adults is taken, and breeding success is not significantly affected (Cuthbert 1999, Cuthbert and Davis 2002). A more likely cause of current poor breeding success, and a potential threat to future population stability, is the availability of high quality prey at sea (Sommer et al. 2009). Modelling has demonstrated that colonies are most vulnerable to the loss of breeding adults and therefore maintaining high survivorship is paramount (Cuthbert et al. 2001). Habitat destruction and predation by feral pigs, along with heavy browsing by a range of introduced herbivores may have been the cause of the complete destruction of some subcolonies by erosion (Sherley 1992, Heather and Robertson 1997). Feral pigs and cats are considered the greatest potential threat, but are normally absent from the two remaining colonies (Cuthbert 1999, 2002; Taylor 2000), although it is likely that predation and habitat destruction by feral pigs may have been the key factor in the range contraction of the species in the past (Sommer et al. 2009). Heavy snowfall can crush burrows, and late snow cover can delay or prevent breeding. Birds are sometimes caught in set-nets and inshore longliners, and as many as 80 have been reported to be caught in a single net (Harrow 2009). The impact of long-term over-harvesting of some inshore fish species may be severe (Taylor 2000). The species is potentially threatened by climate change because it has a geographically bounded distribution: its altitudinal distribution falls entirely within 2,000 m of the highest mountain top within its range (2,885 m) (BirdLife International unpublished data).

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
On-going control of browsing animals has resulted in a substantial improvement in vegetation cover (Heather and Robertson 1997), and a decrease in the number of burrows destroyed by trampling. A long-term project to monitor threats, and another to study population dynamics, have been established, and are on-going (Taylor 2000). Pigs are controlled on the colony boundaries (Cuthbert 1999). A third population is being established on the Kaikoura Peninsula: 10 fledglings were transferred there in 2005, 80 in 2006, c.100 in 2007 and 100 in 2008 (Anon 2007, Ombler 2010).

Conservation Actions Proposed
Census the population every five years using burrow plots and photopoints. Monitor focal burrows annually and correlate results with climatic and marine fluctuations. Commence nest protection if present research indicates predation is having a significant effect. Assess the impact of local fisheries on food availability (Taylor 2000). Re-establish colonies at accessible sites along the flight path (Cuthbert 1999).


Citation: BirdLife International 2012. Puffinus huttoni. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 23 September 2014.
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