Writing in Notornis, journal of the Ornithological Society of New Zealand, P.A. Fraser reports sighting over 1200 Westland Petrels Procellaria westlandica, many in primary moult, in November 2005 among the fjords and channels of southern Chile.
With the annual breeding population of this New Zealand winter-breeding endemic estimated as 4000 pairs in 2008 (see the ACAP Species Assessment), and an earlier assessment of the population visiting South America as of the order of 3500 birds in the austral spring (Spear et al. 2005) it is clear that Chilean waters are now confirmed as being important for the species (see also Brinkley et al. 2000 for historical South American records).
Conservation of the Westland Petrel thus requires efforts both by New Zealand, on its breeding grounds, and Chile, primary site of its non-breeding distribution.
References:
Brinkley, E.S., Howell, S.N G., Force, M.P., Spear, L.B. & Ainley, D.C. 2000. Status of the Westland Petrel (Procellaria westlandica) off South America. Notornis 47: 179-183. http://www.notornis.org.nz/free_issues/Notornis_47-2000/Notornis_47_4_179.pdf
Fraser, P.A. 2009. Westland Petrels (Procellaria westlandica) off the coast of Chile. Notornis 56: 98-99. http://www.notornis.org.nz/contents.php?volume_issue=n56_2
Spear, L.B., Ainley, D.G. & Webb, S.W. 2005. Distribution, abundance, habitat use and behaviour of three Procellaria petrels off south America. Notornis 52: 88-105. http://www.notornis.org.nz/free_issues/Notornis_52-2005/Notornis_52_2_88.pdf
John Cooper, ACAP Information Officer, 10 January 2009