Document ID: chunk:federal_register_of_legislation:F2022L00775:reg:18:p53
Version: federal_register_of_legislation:F2022L00775
Segment Type: reg
Provision Reference: reg 18 (pt 53/152)
Character Range: 186717–189721

and Trends
The total population is estimated to number between 300,000-350,000 individuals (Brooke 2004) and an estimated 106,000 breeding pairs (Cuthbert and Davis (2002). Although this species is believed to have a stable population, it suffered a historical decrease in range and population size. It qualifies as endangered under IUCN criteria because breeding is now restricted to just two colonies, which remain vulnerable to feral pigs that occur in adjoining areas of the Kaikoura Mountains. The proportion of birds using Australian waters during the non-breeding season is unknown.

   Conservation Concerns and Actions
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 likely extirpated by feral pigs, which remain a potential threat to the remaining two colonies (Harrow 2009). Since the rapid extirpation of colonies was detected, a third population on the Kaikoura peninsula has been established through translocation of chicks (Anon 2007, Ombler 2010).

 84 Wildlife Conservation Plan for Seabirds
Species profiles

Introduced stoats (Mustela erminea) are known to prey on burrowing seabirds (Moors and Atkinson 1984, Lyver 2002), and their continued presence in both
remaining colonies is of major concern for the future survival of the species
(Sherley 1992). Initially, stoats were thought to be the primary cause of the species decline (Sherley 1992, Heather and Robertson 1997); however, longer-term research has shown that only a small proportion of adults are taken, and the impact on breeding success could be insignificant (Cuthbert 1999, Cuthbert and Davis 2002). Predation and disturbance by feral pigs and cats are considered a major potential threat but are normally absent from the breeding range (Cuthbert 1999, Taylor 2000, Cuthbert 2002). Habitat degradation and predation by feral pigs (Sus scrofa), along with heavy browsing by a range of introduced herbivores may have been the cause of the complete destruction of some sub-colonies, contributing considerably to habitat loss and range contraction (Sommer et al. 2009).

Incidental capture in set-nets and inshore long-liners is also a concern, with up to 80 individuals being caught in a single net (West and Imber 1985, Darby and Dawson 2000, Harrow 2009). In addition, long-term over-harvesting of some inshore fish species could compromise prey availability to Hutton's Shearwaters with adverse impacts (Taylor 2000). Modelling has demonstrated that colonies are most vulnerable to the loss of breeding adults; therefore, maintaining high survivorship is paramount (Cuthbert et al. 2001).

Climate change poses a potential threat to the species. Breeding at high altitude makes the species susceptible to detrimental effects of abnormal amounts or timing of snowfall; heavy snowfall can crush burrows, and late snow cover can delay or