Justification of Red List Category
This species has a very large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Brooke (2004) estimated the global population to number at least 100,000 individuals.
The population is suspected to be in decline owing to predation by invasive species.
This species is a common and widespread species endemic to New Zealand. The largest colonies are found in the Three Kings group, Moturoa group, Motuharakeke (Cavalli Islands), north-west Chickens, Bream Islands, Mokohinau group, Channel Island, Mercury group, Ruamahuanui (Aldermen group) and Trio Islands, as well as on several other islands in the Cook Strait. Fledglings, and possibly some adults, move towards the east and south of Australia in February, but most remain near to breeding colonies throughout the year (Marchant and Higgins 1990, Powlesland and Rickard 1992).
This species breeds on small, vegetated islands and rock stacks. It nests in colonies in burrows under grass, scrub or coastal forest, but occasionally breeds in rocky cavities (Marchant and Higgins 1990). The breeding biology of the species is very poorly known, but laying of eggs is believed to begin in early September, and chicks fledge from late January (Powlesland and Rickard 1992). Birds feed mostly on fish and some coastal krill (Marchant and Higgins 1990).
Historically, the species has been extirpated from several breeding locations by introduced feral cats Felis catus, House Rats Rattus rattus and Brown Rats R. norvegicus. Invasive rats have now been successfully removed from considerable parts of the breeding range, yet they are still present and likely to have a negative impact on breeding success. At present, the species survives mostly on islands free of introduced mammals, but some persist in coexistence with populations of Polynesian Rat R. exulans and R. rattus (Saddle Island). These populations are relatively small, and the rats may be having a significant effect on breeding success there. There is a future risk of re-invasion on currently predator-free islands (BirdLife International 2016). Other potential threats include overharvesting of inshore prey stocks, bycatch in hand and reel-lines and set-nets. Fluttering Shearwaters are frequently trapped in fishing gear in inshore waters, with unknown impacts on the global population.
Conservation Actions Underway
Polynesian Rat Rattus exulans has been eradicated from at least 14 island colonies in the last 15 years, as well as rabbits, goats and cats. A long-term experiment to establish a new breeding colony by the translocation of chicks was commenced in 1991 (Bell 1995). Pairs have since become established there, and breeding has occurred in consecutive breeding seasons since 1996 (Powlesland and Rickard 1992, B. D. and D. Bell in litt. 1999).
Text account compilers
Fjagesund, T., Ekstrom, J., Hermes, C., Butchart, S., Martin, R., Newton, P., Stuart, A.
BirdLife International (2020) Species factsheet: Puffinus gavia. Downloaded from http://www.birdlife.org on 29/01/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 29/01/2020.