Biology
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Like other shearwaters, this species flies fast and often low over the ocean (2). Here it forages, often in association with wedge-tailed shearwaters, sooty terns and boobies, for small fish and squid (2). It dives into the water to pursue and capture its prey, often exploiting the actions of tuna and cetaceans, as they drive shoals of small fish to the surface (2).
In the last week of April, adult Newell's shearwaters arrive at their island nesting grounds. During the first two weeks of June, they lay a precious, single egg into a burrow which has been dug under matted ferns or tussock grass (2), often at the base of a tree (4). The egg is thought to be incubated for around 51 days by both parents (2), who continue their parental care when the egg hatches, spending the daylight hours foraging in the ocean surrounding the island, travelling up to 1,200 kilometres from the colony, and returning at night to feed the chick (2) (4). By November, the young will have fledged and the parents provide no further care, leaving the young to start life on the open oceans (4). During the first year of life, Newell's shearwaters do not visit breeding islands, but as they age, they will visit colonies for progressively longer periods, until they first breed at the age of six (2).
Conservation
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Several conservation actions have been initiated for this Endangered bird. In 1978, a campaign to rescue and rehabilitate fallen fledglings began (4). Entitled Save our Shearwaters, this campaign recovers and releases around 1,500 disorientated shearwaters each year (2) (4). Since the early 1980s, efforts have been made to reduce the amount of glaring lights that attract and disorientate shearwaters (4). In 2006, a law was passed which requires all non-essential lights to be turned off or shielded between September and December on Kaua'i, when young shearwaters leave their nests (6), and recently, hoods (to prevent lights shining into the sky) have been installed on all lights on the island (4).
These are fantastic efforts, but yet more needs to be done to ensure the future survival of this species. Future recommended management measures include controlling introduced predators, eradicating invasive plants from the sites of shearwater colonies, and continuing to identify areas where the use of artificial lights and powerlines can be minimized (4).
Description
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Newell's shearwater is called the 'A'o in Hawaii, a name given for the moan-like call this seabird emits when in its burrow, which Hawaiians once believed sounded like an omen of death (3). This attractive bird and magnificent flier is undeserving of such an association, and is now so rare, one would be lucky to hear its nesting cry (3). It has dark, sooty brown plumage on its upperparts and white underparts, with the white extending up the throat and to the sides of the rump (2) (4). It has a dark bill (4), with a hooked bill and sharp blades, enabling it to deal with slippery prey with ease (5).
Habitat
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Newell's shearwaters are oceanic birds, found north of the equator over waters deeper than 2,000 metres (2). It nests on steep, mountain slopes, typically between 160 and 1,200 metres above sea level and up to 14 kilometres from the coast (2).
Range
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Newell's shearwater breeds only on the Hawaiian Islands: principally Kaua'i, but also Hawai'i and Moloka'i, and possibly also on O'ahu, Maui, and Lana'i (6). At other times of the year, this oceanic bird wanders far over the central Pacific Ocean (2).
Status
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Classified as Endangered (EN) on the IUCN Red List (1).
Threats
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Since 1992, numbers of Newell's shearwaters on Kaua'i have been declining. Although this decline is thought to be associated with the impacts of Hurricane Iniki, which hit the island in 1992, numerous other factors could also be implicated. Artificial lighting on the breeding islands, such as street and resort lights, is affecting large numbers of Newell's shearwaters. Lights disorientate fledglings as they depart the island for life at sea, causing them to crash into powerlines, communication towers or other structures, or fall to the ground exhausted. Once on the ground, the small birds are vulnerable to cars, cats, dogs, starvation and dehydration, resulting in thousands perishing each year (4).
When nesting, Newell's shearwater is vulnerable to predation from introduced mammals (4). Feral cats have been recorded killing nesting birds in their burrows (4), and rats are believed to prey on eggs and chicks (6). Also of concern is the small Asian mongoose (Herpestes javanicus), another potential predator that has recently been discovered on Kaua'i (6). Newell's shearwater is likely to be impacted by the loss and degradation of suitable nesting habitat. Already 75 percent of Kaua'i's natural forest has been lost in the last 150 years (4), and the remaining forest is now being impacted by introduced plants, pigs and goats (4) (6). Out at sea, overfishing of tuna species, which aid the shearwater by driving prey to the surface, may eventually affect this bird (4).
Finally, given that the majority of Newell's shearwaters breed on a single island, this makes them highly vulnerable to the impacts of catastrophic events, such as hurricanes (4). The declines observed in this species since the hurricane of 1992 illustrate this sobering situation only too well (6).
Newell's shearwater
provided by wikipedia EN
Newell's shearwater or Hawaiian shearwater (ʻaʻo), (Puffinus newelli) is a seabird in the family Procellariidae. It belongs to a confusing group of shearwaters which are difficult to identify and whose classification is controversial. It was formerly treated as a subspecies of the Manx shearwater (Puffinus puffinus) and is now often placed in Townsend's shearwater (Puffinus auricularis). It is endemic to the Hawaiian Islands.
Description
It is a fairly small shearwater, 33 centimetres (13 in) in length. The wing is 223–249 millimetres (8.8–9.8 in) long and the tail is 78.9–88.8 millimetres (3.11–3.50 in). The bird weighs 0.340–0.425 kilograms (0.75–0.94 lb).[2] The upperparts are black with a brown tinge while the underparts are white. The dark colouration on the face extends below the eye and is sharply separated from the white throat. There is a white patch on the flanks, extending onto the sides of the rump. The underwings are mainly white with a dark border. The undertail-coverts have a black and white pattern and appear white in the field. The bill is dark grey or brown and the legs and feet are mainly pale pink. The bird flies low over the water on stiff wings with a mixture of short glides and periods of rapid flapping. It utters a donkey-like braying call around the breeding areas. Townsend's shearwater (P. auricularis) is very similar but has dark undertail-coverts, a shorter tail and a less sharp boundary between the black and white on the face.
Systematics
It was described as a new species Puffinus newelli in 1900 by the American ornithologist Henry Wetherbee Henshaw using specimens obtained by Brother Matthias Newell from residents of Maui. It was later included by some authors in the Manx shearwater (Puffinus puffinus) as was Townsend's shearwater (Puffinus auricularis).[3] Later, Townsends's shearwater was raised back to species status with Newell's shearwater as a subspecies of it. This taxonomy was followed by the American Ornithologists' Union from the sixth edition of its checklist onwards.
However Newell's differs from Townsend's shearwater in various measurements and has a different breeding season and marine habitat.[4] It is now often treated as a separate species, e.g. by BirdLife International following Brooke (2004).[5] In 2004, a study of mitochondrial DNA sequences suggested a close relationship between Rapa shearwater (Puffinus myrtae) and Newell's shearwater and the authors proposed that Rapa shearwater be treated as a subspecies of P. newelli pending further study.[6] The Rapa shearwater is now treated as a full species.
Distribution
It breeds in at least 20 colonies on mountain slopes in the Hawaiian Islands. The main colonies are on Kauaʻi, on slopes around the Alakaʻi Plateau and probably in the Mokolea Mountains.[7] Its distribution on the other islands is uncertain but it is known to breed on Molokaʻi and the island of Hawaiʻi and may breed on Oʻahu, Maui and Lānaʻi.[8] From April to November it can be seen in the waters around the Hawaiian Islands, particularly around Kauaʻi. Outside the breeding season it disperses into the tropical Pacific Ocean. Its distribution at sea is little known but many move south and east into the waters of the Equatorial Counter Current. It has been recorded as far west as the Mariana Islands. In the south there are records from Samoa in September 1977 and American Samoa in January 1993.[9]
Behaviour
Feeding
It feeds far from land, in areas of deep water (at least 2000 meters). Its diet is little known but includes squid and small fish. It dives into the water to catch its prey, swimming down to a depth of up to 10 meters using its wings to move forward. It is attracted to schools of tuna and gathers in flocks with other seabird species to catch prey driven to the surface by the tuna.[10]
Reproduction
By 1908, it was thought to be extinct but was rediscovered in 1947 and found breeding on Kauaʻi in 1967. The nest site is a burrow dug into a steep slope, usually sheltered by uluhe (Dicranopteris linearis ferns). A single white egg is laid during the first two weeks of June. Both parents incubate the egg and an incubation period of 62 days has been recorded. The young birds leave the nest in October, 88–100 days after hatching. They fly out to sea and are no longer dependent on their parents.[11]
Conservation
It was formerly a much more common bird with a wider breeding distribution in the islands. It has declined due to habitat loss and predation by introduced species such as mongooses, rats, cats and barn owls.[12] Young birds in particular are attracted to the lights of urban areas at night and many die in collisions with power lines and buildings. The population was estimated at 84,000 birds in the mid-1990s. A severe decline has occurred in recent years which may be associated with the effects of Hurricane Iniki in 1992.[5]
Footnotes
References
- Ainley, D. G., T. C. Telfer, and M. H. Reynolds (1997). Townsend’s and Newell’s Shearwater (Puffinus auricularis). In The Birds of North America, No. 297 (A. Poole and F. Gill, eds.). The Academy of Natural Sciences, Philadelphia, PA, and The American Ornithologists’ Union, Washington, D.C. Accessed 20/09/07. [subscription required]
- Austin, Jeremy J., Bretagnolle, Vincent & Pasquet, Eric (2004). A global molecular phylogeny of the small Puffinus shearwaters and implications for systematics of the Little-Audubon's Shearwater complex., Auk, 121(3):847-864.
- Beolens, Bo & Watkins, Michael (2003). Whose Bird?: Men and women commemorated in the common names of birds, Christopher Helm, London.
- BirdLife International (BLI) (2007). Species factsheet: Puffinus newelli. Downloaded from http://www.birdlife.org on 20/9/2007
- Melgar, Christian (2002) Newell's Shearwater (Puffinus newelli). Accessed 20/09/07.
- Murphy, Robert Cushman (1952). The Manx Shearwater, Puffinus puffinus, as a species of world-wide distribution. American Museum Novitates, 1586:1-21.
- Pratt, H. Douglas; Bruner, Philip L. & Berrett, Delwyn G. (1987). A Field Guide to the Birds of Hawaii and the Tropical Pacific, Princeton University Press, Chichester.
- The Ornithological Society of Polynesia. Birds of Rapa. Accessed 20/09/07.
-
Watling, Dick (2001) A Guide to the Birds of Fiji & Western Polynesia, Environmental Consultants (Fiji), Suva.
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Newell's shearwater: Brief Summary
provided by wikipedia EN
Newell's shearwater or Hawaiian shearwater (ʻaʻo), (Puffinus newelli) is a seabird in the family Procellariidae. It belongs to a confusing group of shearwaters which are difficult to identify and whose classification is controversial. It was formerly treated as a subspecies of the Manx shearwater (Puffinus puffinus) and is now often placed in Townsend's shearwater (Puffinus auricularis). It is endemic to the Hawaiian Islands.
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- Wikipedia authors and editors
