Pterodroma sandwichensis

Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

Conservation Actions

Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
ANIMALIA	CHORDATA	AVES	Procellariiformes	Procellariidae

Scientific Name:

Pterodroma sandwichensis

Species Authority:

(Ridgway, 1884)

Common Name/s:

English

–

Hawaiian Petrel

Assessment Information [top]

Red List Category & Criteria:

Vulnerable B2ab(iv,v) ver 3.1

Year Assessed:

2008

Assessor/s

BirdLife International

Evaluator/s:

Butchart, S. & Taylor, J. (BirdLife International Red List Authority)

Justification:
This species qualifies as Vulnerable because it has a very small breeding range. It is known from five locations in the main Hawaiian islands, and the future of at least two are in jeopardy (Mauna Loa and West Maui). Its limited distribution and declines primarily result from predation by introduced mammals and urbanisation.

History:

2007	–	Vulnerable
2006	–	Vulnerable
2004	–	Vulnerable
2000	–	Vulnerable
1994	–	Vulnerable
1988	–	Lower Risk/least concern

Geographic Range [top]

Range Description:	Pterodroma sandwichensis ranges in the central Pacific and breeds on the Hawaiian Islands (USA), where an estimate, supported by pelagic surveys, put the total population at 19,000 (range 10,600-34,400), including a best estimate of 4,500-5,000 breeding pairs^1,10. However, the discovery of previously unknown colonies in 2006-2007 may bring the total population closer to the upper estimate of 6,500-8,300 pairs¹⁰. The observation of birds' movements by radar suggests that the total number on Maui exceeds the current estimate of 1,800 individuals¹². Approximately 1,200 burrows are known in Haleakala Crater, Maui, although not all of these are used every year¹⁷, and two small colonies are present in the West Maui Mountains^12,17, but they are so far unquantified¹⁷, with numbers perhaps in the tens or low hundreds¹⁹. On Hawai`i, small numbers breed on Mauna Kea and 40-50 pairs were present on Mauna Loa prior to 1995^1,9. On Kaua`i, 1,600 pairs are indicated by observations of birds at a rafting site¹. On Moloka`i, 5-10 birds were heard calling in 1980, suggesting small numbers⁹, but there has not been a concerted effort to estimate numbers on this island¹⁹. Surveys in 2006-2007 located a colony in the cloud forests of Lanaihale on the north side of Lâna`i^11,21. This population probably numbers several thousand birds, based on the volume of calling during night time listening surveys in April and May along the Lana`ihale ridge at the highest point in the uplands, although only 14 burrows had been found by October 2007¹⁷. Surveys have so far been hampered by weather conditions and the risk of habitat disturbance¹⁷.
Countries:	Native: French Polynesia; United States Vagrant: Indonesia; Japan; Philippines
FAO Marine Fishing Areas:	Native: Pacific – eastern central
Range Map:	(click map to view full version)

Population [top]

Population:	Spear et al. (1995) give a best estimate of 3,750-4,500 breeding pairs based on at-sea surveys. However, the discovery of possibly several thousand birds breeding on Lâna`i during terrestrial surveys in 2006-2007 and two small colonies on West Maui (J. Penniman in litt. 2007), probably in the tens or low hundreds of birds (D. Ainley in litt. 2007), brings the estimated breeding population close to the upper estimate of 6,500-8,300 pairs calculated by Spear et al. (1995).
Population Trend:	Decreasing

Population:

Spear et al. (1995) give a best estimate of 3,750-4,500 breeding pairs based on at-sea surveys. However, the discovery of possibly several thousand birds breeding on Lâna`i during terrestrial surveys in 2006-2007 and two small colonies on West Maui (J. Penniman in litt. 2007), probably in the tens or low hundreds of birds (D. Ainley in litt. 2007), brings the estimated breeding population close to the upper estimate of 6,500-8,300 pairs calculated by Spear et al. (1995).

Population Trend:

Decreasing

Habitat and Ecology [top]

Habitat and Ecology:	On Maui, Mauna Kea and Mauna Loa, nesting takes place mainly between 2,000 and 3,000 m, in lava cavities with little vegetation nearby¹⁹. Elsewhere, for example West Maui¹⁷ and Kaua`i¹⁸, it nests at lower elevations, amongst dense shrubs and ferns¹⁹, or in native grasslands with bracken^1,3,9. On Haleakala, Maui, birds nest in rock crevices and tunnels that are over 0.5 m deep, often exceeding two metres¹⁷. Generally, the nest chamber can be from one to nine metres deep²⁰. Pairs nest in cavities in the volcanic terrain, in burrows beneath rocks or at the base of clay cliffs¹⁸. At lower altitudes, they excavate burrows or nest in cavities often at the base of trees^3,9,18, although many burrows on Lâna`i are not at the base of trees¹⁷. It takes each bird five to six years to reach maturity¹⁶. Most eggs are laid in May and June, with most young fledging by December²⁰. The diet comprises mostly fish and squid, with squid constituting c.50-75% of the food ingested⁹. The species ranges in the north Pacific to around 50^{N when foraging for chick provisioning17}. It has been found that at least some birds nesting on Lâna`i feed in waters around the Aleutian Islands, as shown through the use of tracking devices on several breeding individuals²¹. The species usually forages in mixed species flocks, typically over schools of predatory fish species²⁰.
Systems:	Marine

Habitat and Ecology:

On Maui, Mauna Kea and Mauna Loa, nesting takes place mainly between 2,000 and 3,000 m, in lava cavities with little vegetation nearby¹⁹. Elsewhere, for example West Maui¹⁷ and Kaua`i¹⁸, it nests at lower elevations, amongst dense shrubs and ferns¹⁹, or in native grasslands with bracken^1,3,9. On Haleakala, Maui, birds nest in rock crevices and tunnels that are over 0.5 m deep, often exceeding two metres¹⁷. Generally, the nest chamber can be from one to nine metres deep²⁰. Pairs nest in cavities in the volcanic terrain, in burrows beneath rocks or at the base of clay cliffs¹⁸. At lower altitudes, they excavate burrows or nest in cavities often at the base of trees^3,9,18, although many burrows on Lâna`i are not at the base of trees¹⁷. It takes each bird five to six years to reach maturity¹⁶. Most eggs are laid in May and June, with most young fledging by December²⁰. The diet comprises mostly fish and squid, with squid constituting c.50-75% of the food ingested⁹. The species ranges in the north Pacific to around 50^{N when foraging for chick provisioning17}. It has been found that at least some birds nesting on Lâna`i feed in waters around the Aleutian Islands, as shown through the use of tracking devices on several breeding individuals²¹. The species usually forages in mixed species flocks, typically over schools of predatory fish species²⁰.

Systems:

Marine

Threats [top]

Major Threat(s):	Historically the species suffered declines through harvesting by Polynesians after they arrived c.1,800 years ago¹³. The species was eliminated from many islands in the archipelago, and it may already have been restricted to its current breeding range when Europeans arrived¹³. Nesting habitat has since been lost to urbanisation and degraded by feral goats and pigs. Nest burrows are trampled by feral goats, mouflon sheep and potentially chital Axis axis²⁰. The most serious current threat is predation by introduced vertebrates including feral cats, Barn Owls Tyto alba, rats, dogs, pigs and the small Asian mongoose Herpestes javanicus (although the latter is not yet established on Lâna`i). Nestlings are very susceptible to predation, as they cannot fly for more than 15 weeks after hatching¹⁶. The population on Hawai`i is probably declining as a result, and the south-east Mauna Loa colony may soon be lost⁹. The species is currently threatened with habitat disturbance by goats, pigs and cattle¹³. On Lâna`i, habitat degradation caused by the invasive tree, strawberry guava Psidium cattleianum, may be the biggest threat to the long term survival of the colony¹⁷. On occassion, fledglings become grounded after colliding with lights⁸, and mortality sometimes results from collisions with fences and powerlines^4,9. Once on the ground, fledglings are unable to fly and are killed by cars or cats and dogs, or die from starvation or dehydration²⁰. The species may be threatened by plans for a field of wind generators on Lâna`i¹¹, although following the discovery of large numbers nesting on the island measures to minimise and mitigate any impact on the species are being developed¹⁷. The species may be adversely affected by declines in the populations of large predatory fish that drive prey species to the surface¹⁷. In addition, a significantly lower percentage of birds come ashore to nest during El Niño years (c.40% compared to c.65% normally)¹⁴, suggesting that the species is sensitive to such disturbances in environmental conditions¹³.

Major Threat(s):

Historically the species suffered declines through harvesting by Polynesians after they arrived c.1,800 years ago¹³. The species was eliminated from many islands in the archipelago, and it may already have been restricted to its current breeding range when Europeans arrived¹³. Nesting habitat has since been lost to urbanisation and degraded by feral goats and pigs. Nest burrows are trampled by feral goats, mouflon sheep and potentially chital Axis axis²⁰. The most serious current threat is predation by introduced vertebrates including feral cats, Barn Owls Tyto alba, rats, dogs, pigs and the small Asian mongoose Herpestes javanicus (although the latter is not yet established on Lâna`i). Nestlings are very susceptible to predation, as they cannot fly for more than 15 weeks after hatching¹⁶. The population on Hawai`i is probably declining as a result, and the south-east Mauna Loa colony may soon be lost⁹. The species is currently threatened with habitat disturbance by goats, pigs and cattle¹³. On Lâna`i, habitat degradation caused by the invasive tree, strawberry guava Psidium cattleianum, may be the biggest threat to the long term survival of the colony¹⁷. On occassion, fledglings become grounded after colliding with lights⁸, and mortality sometimes results from collisions with fences and powerlines^4,9. Once on the ground, fledglings are unable to fly and are killed by cars or cats and dogs, or die from starvation or dehydration²⁰. The species may be threatened by plans for a field of wind generators on Lâna`i¹¹, although following the discovery of large numbers nesting on the island measures to minimise and mitigate any impact on the species are being developed¹⁷. The species may be adversely affected by declines in the populations of large predatory fish that drive prey species to the surface¹⁷. In addition, a significantly lower percentage of birds come ashore to nest during El Niño years (c.40% compared to c.65% normally)¹⁴, suggesting that the species is sensitive to such disturbances in environmental conditions¹³.

Conservation Actions [top]

Conservation Actions:	Conservation actions underway: CMS Appendix I. On Maui, there is a long-term monitoring programme in the Haleakala National Park⁹ and efforts are made to control introduced mammals. In 1976, a perimeter fence was put up around the main colony to exclude feral goats and pigs from the habitat¹³. The predator exclosures placed around the national park may have facilitated an increase in the number of birds in eastern Maui¹². The trapping of rats started in 1968, and since 1997 rodenticides have been used¹³. Cats and mongooses have been controlled since 1981, and trapping of these species and rats continues to be carried out year-round¹³. On Lâna`i: colony delineation surveys are continuing¹⁷, and as burrows are found they are included in basic breeding biology study; feral cats are being trapped and removed; studies on Tyto alba are being designed; a rat population assessment was due to begin in 2007, with control by rodenticide to be carried out subsequently; habitat restoration work may begin in January 2008; and public education projects will be implemented in 2008¹⁷. In 2006, a fence was completed to encircle a large portion of the breeding habitat on Lâna`i; the purpose was to exclude ungulates that damage the vegetation thus impacting the island's water supply¹⁹. Simultaneously, a limited cat-trapping programme has been initiated in the fenced area¹⁹. On Maui, Lâna`i, and Kaua`i, grounded fledglings are collected and released, although the benefit of doing this has yet to be confirmed as very few banded individuals have subsequently been encountered¹⁹. Fencing erected for forest conservation has been modified to reduce collisions⁹. On Kaua`i, auditory surveys to detect colonies are ongoing, and have included documenting the first known nesting sites on Kaua`i in the Upper Limahuli Preserve¹⁸. Also on Kaua`i, street lighting is shielded in critical areas and lighting on some buildings has been modified to reduce collisions^2,9. A ruling brought by the U.S. Fish and Wildlife Service in 2006, under the U.S. Endangered Species Act, has enforced a campaign running since 2005, 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 nests¹⁵. The island's electricity company is helping by darkening all of its 3,000 street lights, and shielding or turning some of them off. The company has also fitted large balls to power lines in an effort to reduce the number of birds that collide with the cables¹⁵. Significant improvements have beem made in reducing light attraction and collision, although there is still a considerable amount of new and existing infrastructure that requires modification¹⁸. Methods are currently being developed to quantify the population on each island¹⁷; surveys for colonies on West Maui are being carried out¹⁷ and surveys on Moloka`i were planned to begin in Spring 2008¹⁷. Conservation actions proposed: Improve radar sampling for use as a population monitoring technique^17,19. Use passive integrated transponder (PIT) tags to study colony attendance by breeding pairs¹⁷. Reduce collisions with power lines by making them more visible, burying them or moving them further inland where birds fly higher⁴. Ensure lighting does not attract petrels². Control predators in known colonies⁵, and improve measures for the declining colonies at Mauna Loa, Hawai`i¹³ and West Maui¹⁹. Monitor breeding success¹³. Continue to retrieve grounded birds¹³, but conduct research to assess the effectiveness of rehabilitation methods¹⁹. Continue to search for additional breeding areas¹³. Carry out further research into foraging range and feeding behaviour¹³. Investigate the species's vulnerability to human-induced mortality at sea¹³. Investigate the impact of the loss of tuna schools that the species depends upon for foraging¹⁹. Undertake research into the potential effects of climate change on the species¹³.

Conservation Actions:

Conservation actions underway:

CMS Appendix I. On Maui, there is a long-term monitoring programme in the Haleakala National Park⁹ and efforts are made to control introduced mammals. In 1976, a perimeter fence was put up around the main colony to exclude feral goats and pigs from the habitat¹³. The predator exclosures placed around the national park may have facilitated an increase in the number of birds in eastern Maui¹². The trapping of rats started in 1968, and since 1997 rodenticides have been used¹³. Cats and mongooses have been controlled since 1981, and trapping of these species and rats continues to be carried out year-round¹³. On Lâna`i: colony delineation surveys are continuing¹⁷, and as burrows are found they are included in basic breeding biology study; feral cats are being trapped and removed; studies on Tyto alba are being designed; a rat population assessment was due to begin in 2007, with control by rodenticide to be carried out subsequently; habitat restoration work may begin in January 2008; and public education projects will be implemented in 2008¹⁷. In 2006, a fence was completed to encircle a large portion of the breeding habitat on Lâna`i; the purpose was to exclude ungulates that damage the vegetation thus impacting the island's water supply¹⁹. Simultaneously, a limited cat-trapping programme has been initiated in the fenced area¹⁹. On Maui, Lâna`i, and Kaua`i, grounded fledglings are collected and released, although the benefit of doing this has yet to be confirmed as very few banded individuals have subsequently been encountered¹⁹. Fencing erected for forest conservation has been modified to reduce collisions⁹. On Kaua`i, auditory surveys to detect colonies are ongoing, and have included documenting the first known nesting sites on Kaua`i in the Upper Limahuli Preserve¹⁸. Also on Kaua`i, street lighting is shielded in critical areas and lighting on some buildings has been modified to reduce collisions^2,9. A ruling brought by the U.S. Fish and Wildlife Service in 2006, under the U.S. Endangered Species Act, has enforced a campaign running since 2005, 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 nests¹⁵. The island's electricity company is helping by darkening all of its 3,000 street lights, and shielding or turning some of them off. The company has also fitted large balls to power lines in an effort to reduce the number of birds that collide with the cables¹⁵. Significant improvements have beem made in reducing light attraction and collision, although there is still a considerable amount of new and existing infrastructure that requires modification¹⁸. Methods are currently being developed to quantify the population on each island¹⁷; surveys for colonies on West Maui are being carried out¹⁷ and surveys on Moloka`i were planned to begin in Spring 2008¹⁷.

Conservation actions proposed:

Improve radar sampling for use as a population monitoring technique^17,19. Use passive integrated transponder (PIT) tags to study colony attendance by breeding pairs¹⁷. Reduce collisions with power lines by making them more visible, burying them or moving them further inland where birds fly higher⁴. Ensure lighting does not attract petrels². Control predators in known colonies⁵, and improve measures for the declining colonies at Mauna Loa, Hawai`i¹³ and West Maui¹⁹. Monitor breeding success¹³. Continue to retrieve grounded birds¹³, but conduct research to assess the effectiveness of rehabilitation methods¹⁹. Continue to search for additional breeding areas¹³. Carry out further research into foraging range and feeding behaviour¹³. Investigate the species's vulnerability to human-induced mortality at sea¹³. Investigate the impact of the loss of tuna schools that the species depends upon for foraging¹⁹. Undertake research into the potential effects of climate change on the species¹³.

Citation:	BirdLife International 2008. Pterodroma sandwichensis. In: IUCN 2009. IUCN Red List of Threatened Species. Version 2009.2. <www.iucnredlist.org>. Downloaded on 21 November 2009.
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