Ardenna creatopus

Formerly (AOU 1983, 1998) Ardenna was considered part of Puffinus, but now treated as separate on the basis of genetic data (Penhallurick and Wink 2004, Austin et al. 2004, Pyle et al. 2011), which indicate that species in Ardenna and Puffinus form two deeply divergent clades that may not be sister groups. Analyses of morphology and biogeography (Oberholser 1917, Kuroda 1954) had previously recognized species of Puffinus, Ardenna, and the extralimital Calonectris as distinctive groups. Linear sequence of species follows Pyle et al. (2011) (AOU 2016).

Breeds only on a few islands off Chile, where predation by introduced mammals is a concern, and illegal harvest by humans may be causing a decline in the largest occurrence; species ranges widely at sea in the Pacific Ocean, where it may be negatively affected by commerical fisheres; total breeding population is roughly 20,000-30,000 pairs, with recent trend probably relatively stable or slowly declining.

Breeding range is restricted to islands off Chile (Más á Tierra [Robinson Crusoe] and Santa Clara in the Juan Fernández group, and Isla Mocha in Arauco Bay) (AOU 1998). Away from nesting islands, the species ranges at sea off the Pacific coast of the Americas, north at least as far as south-coastal Alaska (AOU 1998).

Coded range extent refers to the terrestrial breeding range, which is less than 150 square kilometers, based on the sizes of the nesting islands..

Breeds at only three locations (AOU 1998, COSEWIC 2004, BirdLife International 2008).

Threats include mortality from introduced predators (coatis, rats, and feral cats on Isla Robinson Crusoe; rats on Isla Santa Clara; rats and probably feral cats on Isla Mocha) (Collar et al. 1992, Guicking 1999, IUCN 2000); illegal harvest of chicks for food on Isla Mocha (Guicking 1999); likely incidental mortality in commercial fisheries; habitat degradation by goats, rabbits, and cattle on Robinson Crusoe (IUCN 2000, BirdLife International 2008); and burrow destruction by chick harvesters on Isla Mocha (Guicking 1999). The species is also vulnerable to mortality from oil contamination (COSEWIC 2004). Predation by coatis may be the biggest threat on Isla Robinson Crusoe (Guicking and Fiedler 2000). Chick harvest may be causing a decline on Isla Mocha (Guicking 1999). The effect of introduced predators on population size and trend on Isla Mocha is unknown (Hodum and Wainstein 2002). The level of incidental mortality in commercial fisheries is unknown, but there is substantial overlap between fishing areas and shearwater locations (e.g., Guicking et al. 2001).