During 1982-1997, I have been involved in a multifaceted study of flightlessness in birds, supported by the National Science Foundation. The work began during my doctoral research on the steamer-ducks (Anatidae: Tachyeres) of southernmost South America (1982, Auk 99:368–372; 1986, Evolution 40: 540–558), and continued with studies of flightlessness in dabbling ducks (1990, Condor 92:639–673; 1993, Wildfowl 44:74–99), seaducks (1989, Wilson Bulletin 101:410–435; 1993, Journal of Vertebrate Paleontology 13:185–199), auks (1988, Auk 105:681–698), penguins (1989, Journal of Zoology 219:269–307), grebes (1989, Evolution 43:29–54), cormorants (1992, Zoological Journal of the Linnean Society 105:155–224), parrots (1992, Journal of Morphology 213:105–145), and the dodo and solitaire (1993, Journal of Zoology 230:247–292). Flightless birds are known from throughout the world—the best-known examples being the penguins and ostrich—and inhabit a great diversity of ecological environments.

The most comprehensive work examines the evolution of flightlessness in rails (Gruiformes: Rallidae), a cosmopolitan, ecomorphologically diverse family in which 58 species (roughly one-third of its members) are (or were, as many are extinct) weakly flighted or completely flightless. Flightless rails range from tiny crakes (Porzana) on the Hawaiian Islands to extinct, giant coots (Fulica) from New Zealand. Major objectives are: (1) a phylogenetic analysis of modern and subfossil rallids; (2) determination of the morphological bases of flightlessness; (3) diagnosis of associated developmental mechanisms; and (4) synthesis of the ecogeographic correlates of flightlessness. See: Philosophical Transactions of Royal Society of London (Ser. B) 353: 1-72; and Ornithological Monograph 53: 1-654.

Methodologies employed include: cladistic analysis of morphology; univariate, allometric, and multivariate morphometry and descriptive comparisons of external anatomy, skeletons, and pectoral musculature; diagnoses of heterochrony; and evaluation of ecogeographical correlates using new methods for comparative biology. Already completed are: compilation of 550+ characters for the reconstruction of the phylogeny of the group; collection of mensural data from 2,000 skin specimens, 950 skeletons, and numerous subfossil elements; and several of the myological dissections. The study examines the evolutionary loss of a morphologically constraining, ecologically vital locomotor mechanism, addresses several biological controversies concerning phylogenetic constraint, ontogeny, adaptation, and interrelationships among anatomical changes, functional reduction, evolutionary rates, cladogenesis, and extinction, and will provide a paradigm for phylogenetic patterns of repeated evolutionary reduction or loss of typically advantageous, anatomically complex characteristics.