Acknowledgments

We are grateful for support from the Biological Resources Division of the U.S. Geological Survey. The following people kindly provided measurements and label data of specimens in their collections (see Appendix 1 for explanation of abbreviations): E. Bauernfeind (NMW), L. R. Bevier (ANSP), K. R. Cebra (CAS), P. R. Colston and M. Adams (Bird Group, BMNH), R. Dekker (NNM), K. L. Garrett (LACM), B. J. Gill (AIM), J. G. Hinshaw (MZ), F. Hertel (UCLA), N. Hyde (MNZ), G. Murphy (ROM), R. K. Panza (CMNH), E. Pasquet (MNHN), F. G. Sibley (PM), R. J. Symonds (UMZC), G. A. Tunnicliffe (CAM), D. E. Willard (FMNH), and C. Wood (UWBM). Collection materials were made available and help provided to PWS by G. F. Barrowclough, C. Blake, M. K. LeCroy, R. Sloss, and P. Sweet (AMNH); C. H. Kishinami and R. L. Pyle (BPBM); R. A. Paynter, Jr. (MCZ); and R. C. Banks (NMNH). Further assistance was provided by M. Adams, P. C. Banko, D. Boynton, M. S. Collins, S. Conant, J. M. Diamond, C. Dove, S. G. Fancy, L. J. Garrett, A. W. Ingersoll, T. Ivison, J. D. Jacobi, A. L. Kaeppler, M. K. LeCroy, J. K. Lepson, W. Manning, S. L. Olson, T. K. Pratt, R. L. Pyle, N. Rollinson, R. J. Shal-lenberger, P. Sweet, T. L. Telfer, C. van Riper III, and L. Walton. D. R. Herbst identified plant materials in nest cup of Kaua'i 'Ö'ö; A. L. Priori (Library of Natural Sounds, Laboratory of Ornithology, Cornell University) furnished copies of original recordings of Kaua'i 'Ö'ö; G. E. Hough II (Borror Laboratory of Bioacoustics [BLB], Ohio State University) interpreted the spectro-grams and offered suggestions for presentation; and S. Gaunt (also BLB) provided sonograms of Kaua'i 'Ö'ö. S. Conant granted permission to use tables from one of her publications. D. G. Krementz and J. M. Meyers (U.S. Geological Survey, Patuxent Wildlife Research Center, Athens, GA) ran the computer programs to generate linear regression for mass estimates and the statistics presented in Appendix 3 . We thank S. Conant, M. P. Morin, A. Poole, H. D. Pratt, K. Russell, and anonymous reviewers for helpful suggestions for improving the manuscript. Cover painting of the 5 Hawaiian honeyeaters is by H. D. Pratt (Pratt et al. 1987 Pratt, H. D., P. L. Bruner, and D. G. Berret (1987). A Field Guide to the Birds of Hawaii and the Tropical Pacific. Princeton University Press, Princeton, NJ, USA. Close ) and is used with his and the Hawai'i Audubon Society's permission. We thank B. J. Fancher for typing the manuscript.