Hawaiian petrel (Pterodroma sandwichensis)

Description

Hawaiian petrel fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Hawaiian petrel description

A large, oceanic bird, the Hawaiian petrel (Pterodroma sandwichensis) is confined to just a few of the Hawaiian Islands. Both the male and female Hawaiian petrel have a dark blackish-brown head, with white below the eyes and on the forehead. The upperparts of the body are also black, while the underparts are white, and some individuals also have white patches on the side of the rump. The underwings are white with black tips and trailing edges. The Hawaiian petrel has a hooked black bill, and pink legs and feet that end in black toes ^{(2) (3) (4)}.

The Hawaiian petrel has a very distinctive call during the breeding season that sounds like 'oo ah oo' ⁽⁴⁾. It also produces a range of other calls, including a low-pitched gurgling noise ⁽²⁾ and calls that sound like a yapping dog ^{(3) (4)}.

Size

Length: 43 cm ⁽²⁾

Wingspan: 90 cm ⁽³⁾

Hawaiian petrel biology

The breeding season of the Hawaiian petrel begins between March and April, when it returns to its nesting site from a life out at sea. Generally the Hawaiian petrel will only start visiting its breeding colony from three years of age, and will not start breeding until it is five to six years old ⁽⁵⁾.

The Hawaiian petrel is a monogamous species, and the male and female will take shifts during the nearly two month incubation period, with each shift lasting an average of 12 days. While incubating the egg, the bird does not have access to food and water, so it usually spends the whole time sleeping in order to minimise the loss of energy. The female lays only one egg per year ⁽²⁾. The Hawaiian petrel chick hatches around the end of July, and the adults will briefly stay and protect the chick before beginning a routine of extended ocean foraging trips to gather food. During this time, both adults are absent from the nest except for visits to deliver regurgitated food to the chick ⁽⁶⁾. Most chicks leave the nest by December ⁽²⁾.

The Hawaiian petrel mainly forages for food at night, flying in flocks with other species of marine birds. Its prey includes fish (such as the lanternfish and goatfish) and squid, the latter representing the majority of the bird's diet ^{(2) (7)}. Unlike some seabirds, the Hawaiian petrel does not dive into the water to feed ⁽⁵⁾. It usually feeds by seizing prey whilst sitting on the water or picks it off the water’s surface while flapping just above, often pattering the water with its feet ⁽⁶⁾.

Hawaiian petrel range

Historically, the Hawaiian petrel was abundant and widely distributed across Hawaii ⁽⁵⁾. It ranges in the central Pacific for most of the year and returns to the Hawaiian Islands for breeding. However, today populations of the Hawaiian petrel are restricted to breeding on just five islands in Hawaii: Maui, Hawai‘i, Kaua‘i, Moloka‘i and Lana‘i ^{(2) (5) (6)}.

Hawaiian petrel habitat

The nesting sites of the Hawaiian petrel may be found at various elevations, depending on the specific island. Where soil is dry and vegetation is scarce (such as on the islands of Hawai'i and Maui), the Hawaiian petrel nests in cavities in the volcanic terrain, such as cracked lava tubes and crevices. It also tends to inhabit wet forests, like those found on Kaua'i, where the nest is built inside burrows or amongst vegetation ^{(2) (6)}.

Hawaiian petrel status

The Hawaiian petrel is classified as Vulnerable (VU) on the IUCN Red List ⁽¹⁾.

Hawaiian petrel threats

The Hawaiian petrel is now limited to a very small breeding range and its population is suspected to have declined severely over the past few centuries ⁽²⁾. The historical decline of this species is likely to be due to hunting by humans, which eliminated the Hawaiian petrel from many of the Hawaiian islands ^{(2) (6)}. Like other seabirds, the Hawaiian petrel is also suffering from the introduction of non-native species. Over the years, dogs, pigs, rats, cats and the small Indian mongoose (Herpestes javanicus) have been introduced to the islands. Predation by these animals affects both adult petrels and their eggs and chicks ^{(2) (6) (7)}. 

Another kind of threat is posed to this species by feral goats and pigs, which may trample nesting burrows ⁽⁶⁾. Urbanisation has also meant a severe decline in nesting sites for the Hawaiian petrel ⁽²⁾.

On the island of Lana`i, the habitat is also being degraded by the spread of the invasive tree strawberry guava (Psidium cattleianum), threatening the long-term survival of the island’s Hawaiian petrel colony ⁽²⁾.

Flying mostly at night, the Hawaiian petrel is often disoriented by artificial lighting, and fledglings may become grounded after flying into lights. Once grounded, the young birds are vulnerable to predators and cars, or can die from starvation ^{(2) (6)}. Collisions with artificial objects, such as power lines and buildings, are also cause for concern ⁽⁶⁾.

The Hawaiian petrel may also be negatively affected by environmental changes in its oceanic feeding grounds, which can alter prey availability ⁽²⁾.

Hawaiian petrel conservation

Efforts to control introduced predators are being made at accessible colonies of the Hawaiian petrel. Fencing the nesting sites has proved a successful way of protecting eggs and chicks from being trampled by goats and pigs, and trapping of cats, mongooses and rats, both inside and outside fenced areas, is also taking place. On Maui, there is a long-term monitoring programme aimed at protecting the Hawaiian petrel in the Haleakala National Park ⁽²⁾.

Regulations brought in by the U.S. Fish and Wildlife Service in 2006 have enforced a campaign that has been running since 2005, in which all non-essential lights on Kaua’i are shielded or turned off between September and December, when young birds leave their nests. Power lines are also being made more visible in order to reduce the rate of collisions and subsequent grounding. For example, on the island of Kaua’i, the main electricity company has fitted large balls to the power lines and is helping to darken or shield all of its 3,000 street lights ⁽²⁾.

The Hawaiian people are very active in the retrieving of grounded birds, thanks to a programme named “Save our Shearwater” that raised public attention on the matter. Several “shearwater aid stations” have been built where birds receive medical attention, if necessary, and are later released ⁽⁶⁾.

Further research and conservation activities for the Hawaiian petrel must be aimed at locating more of its colonies, many of which are situated in remote places or in areas that are difficult to survey ^{(2) (6)}. It will also be important to assess the potential impacts of environmental changes and human-caused mortality of Hawaiian petrels at sea ⁽²⁾.

View information on this species at the UNEP World Conservation Monitoring Centre.

Find out more

Learn more about the conservation of the Hawaiian petrel:

• Hawaii’s Comprehensive Wildlife Conservation Strategy - Hawaiian petrel:
  http://www.state.hi.us/dlnr/dofaw/cwcs/files/NAAT%20final%20CWCS/Chapters/Terrestrial%20Fact%20Sheets/Seabirds/Hawaiian%20petrel%20NAAT%20final%20!.pdf
• Hawaiian Endangered Seabirds - Hawaiian petrel:
  http://hawaiianendangeredseabirds.org/hawaiian-petrel/
• Save Our Shearwaters:
  http://www.kauai-seabirdhcp.info/
• BirdLife International - Hawaiian petrel: 
  http://www.birdlife.org/datazone/speciesfactsheet.php?id=3896

Authentication

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

Glossary

Feral

Previously domesticated animals that have returned to a wild state.

Incubation

The act of incubating eggs, that is, keeping them warm so that development is possible.

Monogamous

Having only one mate during a breeding season, or throughout the breeding life of a pair.

References

1. IUCN Red List (May, 2011)
   http://www.iucnredlist.org/
2. BirdLife International (May, 2011)
   http://www.birdlife.org/datazone/speciesfactsheet.php?id=3896
3. Center for Biological Diversity - Hawaiian petrel (September, 2011)
   http://www.biologicaldiversity.org/species/birds/Hawaiian_petrel/natural_history.html
4. U.S. Fish and Wildlife Service: Pacific Islands Fish and Wildlife Office - Hawaiian petrel species profile (September, 2011)
   http://www.fws.gov/pacificislands/fauna/uau.html
5. Hawaiian Endangered Seabirds - Hawaiian petrel (September, 2011)
   http://hawaiianendangeredseabirds.org/hawaiian-petrel/
6. Mitchell, C., Ogura, C., Meadows, D.W., Kane, A., Strommer, L., Fretz, S., Leonard, D. and McClung, A. (2005) Hawaii’s Comprehensive Wildlife Conservation Strategy. Department of Land and Natural Resources, Honolulu, Hawai‘i. Available at:
   http://www.state.hi.us/dlnr/dofaw/cwcs/files/NAAT%20final%20CWCS/Chapters/Terrestrial%20Fact%20Sheets/Seabirds/Hawaiian%20petrel%20NAAT%20final%20!.pdf
7. National Park Service: Haleakalā National Park - Hawaiian petrel (May, 2011)
   http://www.nps.gov/hale/parknews/upload/UauInformation-NPS.pdf