IUCN threat status:

Vulnerable (VU)

Distribution

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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 (Spear et al. 1995, Ainley et al. 1997a). 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 pairs (Spear et al. 1995). The observation of birds' movements by radar suggests that the total number on Maui exceeds the current estimate of 1,800 individuals (Cooper and Day 2003). Approximately 1,200 burrows are known in Haleakala Crater, Maui, although not all of these are used every year (J. Penniman in litt. 2007), and two small colonies are present in the West Maui Mountains but they are so far unquantified (Cooper and Day 2003, J. Penniman in litt. 2007), with numbers perhaps in the tens or low hundreds (D. Ainley in litt. 2007). On Hawai`i, small numbers breed on Mauna Kea and 40-50 pairs were present on Mauna Loa prior to 1995 (Ainley et al. 1997a, Simons and Hodges 1998). On Kaua`i, 1,600 pairs are indicated by observations of birds at a rafting site (Ainley et al. 1997a). On Moloka`i, 5-10 birds were heard calling in 1980, suggesting small numbers (Simons and Hodges 1998), but there has not been a concerted effort to estimate numbers on this island (D. Ainley in litt. 2007). Surveys in 2006-2007 located a colony in the cloud forests of Lanaihale on the north side of Lna`i (P. Baicich in litt. 2007, A. Wilson in litt. 2007). 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 2007 (J. Penniman in litt. 2007). Surveys have so far been hampered by weather conditions and the risk of habitat disturbance (J. Penniman in litt. 2007).

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© International Union for Conservation of Nature and Natural Resources

Source: IUCN

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