1. Evolution & Ecology Research Centre; School of Biological, Earth and Environmental Sciences; University of New South Wales; Sydney New South Wales 2052 Australia
2. Bioacoustics Research Program; Cornell Lab of Ornithology; Cornell University; Ithaca New York 14853 U.S.A.
3. Cooperative Institute for Marine Resources Studies; Oregon State University; Hatfield Marine Science Centre; Newport Oregon 97365 U.S.A.
4. Pacific Marine Environmental Laboratory; National Oceanic and Atmospheric Administration; Hatfield Marine Science Center; Newport Oregon 97365 U.S.A.