Acknowledgments

We thank S. Alexander, B. Andres, G. Beyersbergen, S. Billerman, P. Brown, W. Campbell, C. Collins, T. Crocker, R. Dias, T. J. Doyle, L. Espinosa Gallegos, D. Gibson, R. Gill, C. Gratto-Trevor, P. Hockey, E. Ieno, J. R. Jehl, Jr., J. Johnson, T. Johnson, K. Krijgsveld, W. Lin, C. Machtans, B. McCaffery, J. McGowan, G. Morrison, M. North, D. Parmelee, M. Peck, G. Peltola, T. Piersma, W. Renaud, P. Sinclair, S. Skagen, B. Skinner, M. Spindler, L. Tibbitts, T. Tobish, L. Underhill, and S. V. Wilson for answering numerous questions and providing us with unpublished information or draft manuscripts. R. Dias helped enormously by translating several articles. D. Parmelee generously offered use of his wonderful illustration. Access to collection specimens was kindly provided by P. Whitehead at Yale University, P. Sweet at the American Museum of Natural History, and D. Long and K. Berge at the California Academy of Sciences. S. Gaunt and the staff at the Borror Laboratory for Bioacoustics, The Ohio State University, and the Cornell Library of Natural Sounds kindly provided sonograms from their collections. JK thanks J. R. Jehl, Jr., for valuable help and advice in the field and K. Krijgsveld for sharing information about a Hudsonian Godwit nest location and providing unpublished data. JK's and Senner et al.'s work at Churchill has been facilitated by logistic support from the Churchill Northern Studies Centre and financial support from the Northern Research Fund and the Arctic Institute of North America. Senner et al.'s work has also received substantial support from the U.S. Fish and Wildlife Service, the Faucett Family Trust, the David and Lucile Packard Foundation, the American Museum of Natural History, and the Arctic Audubon Society. The manuscript benefited considerably from detailed reviews by C. Gratto-Trevor, E. Ieno, J. R. Jehl, Jr., D. Kroodsma, A. Poole, P. Pyle, K. Russell, L. Tibbitts, and S. V. Wilson.