Justification of Red List Category
Previously assumed to have been Extinct following the lack of records since three specimens were collected in the 1800s. However, the species was rediscovered in 2003, with multiple annual records in subsequent years. Although there is very little information on which to base an assessment, the species has been precautionarily classified as Critically Endangered on the basis of an extremely small population which could be susceptible to the impacts of introduced predators. Tentative population estimates (based on recaptures on land and re-sightings of banded birds at sea) indicate a bigger population than was thought, which may well lead to a revision of the Red List criteria and category to which it is assigned.
Seen at sea in small numbers, with ‘flocks’ of 10-20, 11 and 10-30 birds have been recorded during chumming sessions (Flood 2003, Gaskin and Baird 2005, Rayner et al. 2013).
The population may be increasing, but the evidence is scarce and the current population trend remains largely unknown.
Fregetta maoriana was known only from putative fossil material (Holdaway 1999), and from three specimens collected in the 19th century; two from the East Coast of the North Island, New Zealand (Bourne et al. 2004), and one of unknown provenance, but suggested to be from Banks Peninsula, South Island (Medway et al. 2004). However, one individual was observed and photographed off the Mercury Islands, North Island, in January 2003 (Saville et al. 2003). Subsequently 10-20 individuals attracted to ‘chum’ were observed and photographed north of Little Barrier Island, North Island, in November 2003 (Flood 2003). Since then, birds have been observed in the Hauraki Gulf each summer (October to April) (Gaskin and Baird 2005). A review of previous petrel sightings and specimens suggests the New Zealand Storm-petrel may have been present in the Hauraki Gulf for at least the past four decades (Stephenson et al. 2008). A programme of at-sea capture begun in 2005 and culminated in the discovery of breeding burrows on Little Barrier Island in February 2013, following the capture of 31 individuals, DNA analysis, monitoring of breeding condition of individuals, and deployment of tracking devices (Stephenson et al. 2008, Gaskin 2013, Rayner et al. 2013, 2015). Confusion of identification with an undescribed Fregetta taxon (the ‘Coral Sea Storm-petrel') (Walbridge 2014) has seen a re-evaluation of reported sightings off Queensland, New South Wales and Victoria, Australia. Photographs from sightings off Victoria and New South Wales would appear to be New Zealand Storm-petrels (Lester 2012).
The species is present in the Hauraki Gulf and northern New Zealand waters. Its movement patterns are largely unknown, although it is likely that a significant part of the population is resident in northern New Zealand waters throughout the year, with some birds (possibly immatures and/or non-breeders) migrating to Australian waters from March. Sightings and burrow attendance confirm presence from September to July. It probably feeds on small crustaceans and plankton associated with this water, and it is readily attracted to chum slicks (Gaskin and Baird 2005). The breeding season has been confirmed from February (egg-laying) through to June-July (fledging). Nesting burrows are crevice-like in crumbly, rocky, litter-covered ground under forest, and contained downy chicks fledglings in June and July (Tennyson et al. in litt.).
New Zealand Storm-petrel was rediscovered after more than a century without any records, and subsequently found breeding on islands upon which invasive predators, notable Polynesian Rat Rattus exulans and feral cats Felis catus, had been eradicated (Gaskin 2013). It appears likely that the species was reduced to perilously low numbers due to the impacts of invasive species, though there is no data on previous population sizes or breeding locations.
Conservation Actions Underway
The species has benefited from cat and rat-eradication programmes on Te-Hauturu-o-Toi/Little Barrier Island. Determining the likely breeding timing (Rayner et al. 2013) led the discovery of breeding grounds in February 2013 after ten years of searching using radio transmitters fitted to birds captured at sea (Rayner et al. 2015). Maintaining the predator-free status of Te-Hauturu-o-Toi/Little Barrier Island (one of the world’s premier nature reserves) is paramount and a high level of biosecurity measures is in place (maintained by Department of Conservation rangers permanently on the island). A trial artificial colony site using nest boxes and acoustic attraction (ie. using recordings of New Zealand Storm-petrel calls) has been established in 2016 with birds visiting, but so far without breeding.
Conservation Actions Proposed
Due to the fragile nature of known breeding sites, the surveillance of these sites will be kept to a minimum. Searches for breeding sites on other islands will be conducted using techniques successfully employed on Te-Hauturu-o-Toi/Little Barrier Island (Ismar et al. 2015). A successful chick-feeding trial with White-faced Storm-petrels (Young 2013) showed that storm-petrels could be fledged successfully in artificial conditions opening the possibility of future storm-petrel translocations if deemed necessary.
17 cm. A medium-sized storm petrel with noticeably large head, long legs and long feet, the latter projecting well beyond the square tail. Head, neck and upperparts blackish-brown except for pale carpal bar, white rump and uppertail coverts. Breast blackish-brown grading into blackish streaks on white belly, flanks and undertail coverts, but the amount of streaking highly variable. On the dark underwing, there is a pale central patch. Bill, eye, legs and feet black. Toes extend well beyond the tail in flight, which is swift-like with alternating flapping and glides. Similar spp. Black-bellied Storm Petrel Fregatta tropica, much larger, lacks the streaked flanks, generally has a black belly stripe and has broader, more rounded wings. White-bellied Storm Petrel Fregetta grallaria lacks any streaking on the normally white upper breast and belly (some populations have dark bellied forms) and also has broader, more rounded wings, and toes do not project beyond tail. Wilson's Storm Petrel Oceanites oceanicus is all dark ventrally, but does have a similar, but not the same, flight progression.
Text account compilers
Hermes, C., Lascelles, B., Martin, R., Miller, E., Moreno, R., Stuart, A., Symes, A., Taylor, J., Benstead, P., Ashpole, J, Bird, J., Anderson, O., Brooks, T., Butchart, S., Calvert, R., Fjagesund, T.
Scofield, P., Ismar , S., Stahl, J.-C., Baird, K., Szabo, M., Hitchmough, R., Saville, S., Gaskin, C., Rayner, M., Fitzgerald, N., Stephenson, B., Weeber, B., Taylor, G.A., Tennyson, A.
BirdLife International (2020) Species factsheet: Fregetta maoriana. Downloaded from http://www.birdlife.org on 31/10/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 31/10/2020.