PROC. BIOL. SOC. WASH. 103(2), 1990, pp. 432^51 TAXA OF NORTH AMERICAN BIRDS DESCRIBED FROM 1957 TO 1987 M. Ralph Browning Abstract. —Ninety-nine names proposed from 1957 to 1987 for North Amer-ican birds are evaluated. Of these, 35 are judged taxonomically distinct; seven are recognized provisionally; 54 are considered synonyms of established names; and three forms cannot be identified positively. Five names are taxonomic changes, providing new names for forms previously described. Since the publication of the fifth edition of the A.O.U. Check-list (American Orni-thologists' Union 1957), more than 800 forms of birds, world-wide, have been new-ly described; 99 of these are from North America (sensu A.O.U. 1957). About half the names of these North American forms already have been considered, by various authors, to be synonyms of previously ex-isting names, but others have received little or no taxonomic attention. In the following accounts I summarize the taxonomic status of the taxa of North American birds for which names have been proposed since 1957. With minor excep-tions I evaluated each form using the com-parative material available to the original author, including, where possible, the ho-lotypes and paratypes. In evaluating the forms I emphasized the range of variation more than the average difference in any giv-en character. My standard for recognizing subspecies primarily on color has been more stringent than the so-called "75 percent rule"; statements in the accounts that a pop-ulation differs from another means that at least 95 percent of the specimens I com-pared could be identified. Each account includes the original name with the authority and year; complete ci-tations are given in the Literature Cited. The type locality, modified when required, follows. The depository of holotypes or syn-types, when known, is abbreviated and ap-pears in parentheses if I examined the spec-imens or in brackets if not. Abbreviations are: California Academy of Sciences (CAS); Cleveland Museum of Natural History (CMNH); Delaware Museum of Natural History (DMNH); Field Museum of Natu-ral History (FM); Louisiana State Univer-sity Museum of Natural Science (LSUMNS); National Museum of Canada (NMC); pri-vate collection of Amadeo Rea (AMR); Mu-seum of Vertebrate Zoology, University of California at Berkeley (MVZ); Royal On-tario Museum (ROM); San Diego Museum of Natural History (SDMNH); Texas Co-operative Wildlife Collection, Texas A&M University (TCWC); James Ford Bell Mu-seum of Natural History, University of Minnesota (UMM); University of Michigan Museum of Zoology (UMMZ); Utah Mu-seum of Natural History (UMNH); and U.S. National Museum of Natural History (USNM). The present taxonomic status of each new name is next. References with the present name include sources that have provided data or an opinion on the taxonomic status of that name. I summarize characters and ranges, including a more detailed charac-terization as warranted by my study. Com-ments are omitted for forms discussed in my earlier papers (Browning 1974, 1977, 1978, 1979a). Names of genera (except Pi-
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