Justification of Red List category
This species has been declining at an accelerating pace on its breeding islands, principally as a result of depredation by introduced predators, habitat deterioration and hurricanes. Therefore, it is listed as Critically Endangered.
There have been several population size estimates for this species (see Griesemer and Holmes 2011), but the most recent gives a minimum population estimate of 27,011 individuals (Joyce 2016), which roughly equates to 18,000 mature individuals. However, given the decline on Kauai and near extirpation from Maui, the population size could now be far smaller (D. Ainley in litt. 2016). The population size is therefore precautionarily placed in the band 10,000-19,999 mature individuals.
Once abundant, the species has undergone rapid declines in historic times due to overhunting and predation by introduced mammals and was believed to be extinct by 1908, before it was rediscovered in 1947 (Ainley et al. 1997). Radar survey data has shown that, since the hurricane Iniki hi Kaua'i in 1992, the number of individuals on the island may have declined by as much as 93.5% between 1993 and 2013, driven by key threats such as introduced predators, light attraction, collisions with powerlines and habitat alteration (Raine et al. 2017). It is considered that potentially 90% of the global population is from Kaua`i (see Griesemer and Holmes 2011). Using the minimum population estimate of 27,000 individuals (Joyce 2016), and assuming that trends for individuals breeding on other islands are stable, the population declines at >99% over three generations (46.5 years). It is uncertain whether the rate of decline has been consistently that high over the past three generations, though. Without targeted conservation work against the key threats to the species, it is plausible though that such declines may continue into the future.
Puffinus newelli nests principally on the mountains of Kaua`i in the Hawaiian Islands (U.S.A.). Small colonies exist on Moloka'i, Hawai`i and possibly Maui, with unconfirmed records from Lana`i. After not having been recorded on Oahu since the 1700s, a survey carried out in 2016-2017 located the species in two sites at Mount Kaala and at Poamoho, suggesting that it regularly visits or even breeds on the island (Young et al. 2019).
The species breeds in steep and extremely rugged terrain at 160-1,200 m. It usually nests in burrows associated with the root structure of trees, including Ohia lehua (Metrosideros polymorpha) and a dominant understory of densely matted uluhe fern (Dicranopteris linearis) in montane mesic forests on steep slopes (Ainley et al. 1997, N. Holmes in litt. 2007). In general, it can nest in any habitat that is free of predators (Troy et al. 2016, D. Ainley in litt. 2016).
The breeding season begins in April, when birds return to prospect for nest sites and, following an exodus in late April, egg-laying in early June is highly synchronised (NSWG 2005). Pairs produce one egg, which is incubated for an average of 53-54 days, followed by a fledging period of 81-94 days (NSWG 2005). Most young fledge by November (Mitchell et al. 2005). The age at first breeding is around six or seven years (Mitchell et al. 2005). The species's diet is not well known, although it likely consists of fish and squid, particularly flyingfish and Purpleback Flying Squid (Mitchell et al. 2005, Ainley et al. 2014). It forages for hundreds of kilometres offshore, often in large, mixed species flocks associated with schools of large, predatory fish that drive prey species to the ocean surface (Mitchell et al. 2005, NSWG 2005).
The main threat to this species is thought to be predation by non-native species (D. Ainley in litt. 1999, Mitchell et al. 2005, NSWG 2005). Predation of adults and juveniles by feral cats Felis catus and Barn Owls Tyto alba has been documented on almost every colony on Kaua'i, including the most remote sites (NSWG 2005, Griesmer and Holmes 2011). Polynesian Rats Rattus exulans, Black Rats R. rattus, Brown Rats R. rattus and House Mice Mus musculus were inadvertently introduced to the Hawaiian islands as a result of human activity and shipwrecks (Duffy 2010) and may depredate eggs and chicks (NSWG 2005). Brown Rats appear to be more associated with human settlement and do not appear to be as severe a threat as the other two introduced rat species (Raine et al. 2017). Another potential predator, the Small Indian Mongoose Herpestes auropunctatus, has recently been discovered on Kaua'i (NSWG 2005), and could potentially be a greater threat than cats as its smaller size means it may be able to enter breeding burrows more easily (Duffy and Capece 2014). It is yet to establish a permanent presence on the island (D. Ainley in litt. 2016), although it has a history of incursions onto Kaua'i and one was trapped there in 2016 (N. Holmes and A. Raine in litt. 2016). When the Two-spotted Leafhopper Sophonia rufofascia first established on the Hawaiian Islands, it led to habitat loss through feeding on the Uluhe Fern Dicranopteris linearis which provide cover for shearwater burrows (Cooper and Day 1998). The leafhopper was a cause for great concern not only for shearwaters, but also for agricultural crops and native flora; hence a biological control programme was initiated and the insect is now hard to find on Hawai'i (Coll and Wajnberg 2017). Dogs have been shot at Ka'ena Point, while attacking nestling albatrosses and shearwaters (Duffy 2010), but the scale of their impact is unknown. Habitat loss due to conversion and introduction of herbivores like domesticated goats and pigs pose another threat on the Hawaiian Islands (Reed et al. 2012), and have been suggested as a contributing factor for the recent abandonment of some colonies (Troy and Holmes 2008, N. Holmes and A. Raine in litt. 2016).
On Kaua'i, hurricanes Iwa and Iniki devastated the forests in 1982 and 1992, dramatically reducing available nesting habitat and reducing breeding attempts for Newell’s Shearwaters (Ainley et al. 1997, Griesmer and Holmes 2011). Given that a large proportion of the population breeds on Kaua'i, catastrophic events, like hurricanes, represent a serious threat (Mitchell et al. 2005).
During the 1980s and 1990s an estimated 70 adults and 280 subadults each summer, and at least 340 fledglings each autumn, died as a result of collisions with power-lines and communications towers, or indirectly because of light attraction (Podolsky et al. 1998, Anon. 2007). In the surveyed areas on eastern and southern Kaua'i, 350 adults are reported dead each year from collisions with power lines (Podolsky et al. 1998). Fledglings on their first flight to the ocean are particularly susceptible to attraction to artificial light. The birds are attracted and disoriented by coastal street lights and once grounded, unable to fly and often killed by cars, cats or dogs, or die from starvation or dehydration (Mitchell et al. 2005). Between 1978 and 1981, more than 5,000 individuals were grounded on Kaua'i, and more than 30,000 have been found as victims of fallout since 1971 (Anon. 2007, Griesemer and Holmes 2011). Intense rescue programmes have been initiated to find grounded birds and return them to the sea (Everett and Pitman 1993). On Kaua'i, approximately 1,500 fledglings are recovered annually after becoming grounded (Mitchell et al. 2005), although with the suspected steep population decline on Kaua'i, the number of grounded birds is expected to have decreased proportionately (D. Ainley in litt. 2016). Collision with artificial structures (such as powerlines and wind turbines) is another key threat to the species, particularly in flight corridors for subadult and adult birds accessing inland colonies. Nine communications towers have recently been constructed on the Hawaiian Islands without proper consultation, and these are now the subject of an ongoing lawsuit (Anon. 2007). A field of wind generators was planned for Kaua'i and Lana'i (Department of Business, Economic Development and Tourism 2009 in Duffy 2010), without accounting for the potential impacts on this species. Although wind farms have been shown to have only minor effects on other bird species elsewhere, night-flying Shearwaters may be particularly vulnerable and the cumulative effects of construction and maintenance, erosion, vegetation clearing and noise should be accounted for (Duffy 2010). It is not confirmed whether the wind farm projects will be realised (T. Holmes in litt. 2007, A. Raine in litt. 2016).
Plastic pollution poses yet another threat. On Kaua'i, 50% of Newell’s Shearwater fledglings necropsied during 2007–2014 contained plastic items in their digestive tract and there is evidence that the mass and the number of items ingested per bird have also increased since the 1980s (Kain et al. 2016). It is thought that consumption of even small quantities of plastic, including fibres and small fragments, exposes birds at all stages of the breeding cycle to plastic-associated co-pollutants and associated impacts survival (Kain et al. 2016).On Hawai'i, cinder mining has resulted in habitat loss at several colonies (US Fish and Wildlife Service 1983 in Reynolds and Ritchotte 1997, Mitchell et al. 2005) and together with other causes of habitat degradation (invasive vegetation, agriculture and urbanisation) contributes to the exposure and increased predation of ground-nesting birds (Reynolds and Ritchotte 1997). The species is also likely to be impacted by the commercial fishery through bycatch and indirect ecosystem effects resulting from overfishing of tuna Tunnus spp. (Mitchell et al. 2005, Waugh et al. 2012).
Conservation Actions Underway
In the late 1970s, a cross-fostering experiment was carried out at Kilauea Point National Wildlife Refuge (Kaua'i), in which 90 eggs were placed in nests of the Wedge-tailed Shearwater (Ardenna pacifica) (Anon. 2007). Subsequently, 30 young were fledged. Four breeding pairs nesting in 2006 were believed to be descendents of fostered birds (Anon. 2007). Between 2006 and 2013, colony calls were played at the Kilauea Point National Wildlife Refuge and artificial burrows constructed to attract nesting pairs, as there is a low threat from alien predators or collisions with artificial structures (Anon. 2007). Subsequently, up to 13 pairs have been recorded there (N. Holmes and A. Raine in litt. 2016). After the construction of a predator-proof fence in 2015 within the Refuge, 8 chicks were translocated to the site from montane colonies and were raised to fledging (N. Holmes and A. Raine in litt. 2016). It is planned to translocate up to 50 chicks to the Refuge over a five year period (N. Holmes and A. Raine in litt. 2016). Also since 2015, social attraction has also been employed in an attempt to save the population on Maui. While the results are looking favourable, it is too soon to evaluate success (D. Ainley in litt. 2016).
In total, predator control and monitoring activities are in place at six colonies on Kaua'i, which involve the control of cats, rats, pigs and Barn Owls as well as monitoring the effectiveness of these activities through the use of cameras and acoustic monitoring devices (N. Holmes and A. Raine in litt. 2016). On Kauai', Barn Owl control is also carried out at another five colonies located along the Na Pali coast, Kalaheo/Kahili and Hanalei valley (N. Holmes and A. Raine in litt. 2016). The effectiveness of Barn Owl control is being monitored through the deployment of acoustic recording devices via helicopter in management areas (N. Holmes and A. Raine in litt. 2016).
There is an active programme to control lights across Kaua'i. Building's lighting has been effectively re-designed to reduce collisions (Ainley et al. 1997). A ruling brought by the U.S. Fish and Wildlife Service in 2006 under the U.S. Endangered Species Act has enforced a campaign, in which all non-essential lights on Kaua`i are required to be turned off or shielded between 15 September and 15 December when young birds leave their nests (Appel 2006). In the course of the campaign, also street lights are darkened or turned off by the island's electricity company.
Moreover, the electricity company of Kaua'i has started incorporating a range of measures to reduce powerline collisions, including moving lines underground, lowering them, fitting diverters and testing a ‘laser fence’ on key lines to make them more visible to birds moving at night (Griesmer and Holmes 2011, N. Holmes and A. Raine in litt. 2016). Several lawsuits have already been brought forward for violations under the Endangered Species Act (Harrison 2009), including against a hotel which was responsible for over one quarter of all birds downed as a result of light pollution. However, there is still a considerable amount of infrastructure that needs to be modified. It is not expected that the threat posed by artificial lighting will ever be completely eliminated (N. Holmes in litt. 2007). Yet overall, significant improvements have been made to reduce light attraction and collision (N. Holmes in litt. 2007). Over 30,000 downed birds have been rescued and released through the Save Our Shearwaters programme since 1979 (Raine et al. 2017), although few of these birds have subsequently been found again (NSWG 2005, D. Ainley in litt. 2016).
33 cm. Medium-sized shearwater, generally black above and white below. Undertail-coverts white basally, black distally, therefore appearing white (the last is the most useful field character). Similar spp. Townsend's Shearwater P. auricularis, but little or no range overlap. Hints Feeds at ocean fronts along the Equatorial Counter Current. Typical low fast flight of smaller shearwaters, but wingbeat slower than Audubon's Shearwater P. lherminieri.
Text account compilers
Fjagesund, T., Symes, A., Stuart, A., Stattersfield, A., Hermes, C., Taylor, J., Benstead, P., Anderson, O., Ashpole, J, Martin, R., Isherwood, I., Westrip, J., Butchart, S., Calvert, R., Stuart, T.
Ainley, D., Holmes, N & Raine, A.
BirdLife International (2023) Species factsheet: Puffinus newelli. Downloaded from http://datazone.birdlife.org/species/factsheet/newells-shearwater-puffinus-newelli on 02/12/2023.
Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://datazone.birdlife.org on 02/12/2023.