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A zoogeographic analysis of the South American chaco avifauna. Bulletin of the AMNH ; v. 154, article 3

Show simple item record Short, Lester L. en_US 2005-10-06T14:25:07Z 2005-10-06T14:25:07Z 1975 en_US
dc.description p. 165-352 : ill., maps ; 26 cm. en_US
dc.description Includes bibliographical references (p. 349-352). en_US
dc.description.abstract "The South American chaco is centrally situated on the border of the tropics and is xeric-adapted woodland with some open areas, wet places, and savanna. Driest in the center and wettest in the eastern pantanal savanna, the chaco experiences occasional frost throughout. About 409 avian species, including 22 that barely reach its borders, are resident or breed in the chaco. These number 218 nonpasserine birds, 100 suboscine passerines, including 52 tyrant flycatchers, 20 oscine passerines of Old World groups, and 71 New World nine-primaried oscines. Each species is treated taxonomically (based on a systematic reappraisal of each taxon), ecologically, and distributionally. There seem to be more superspecies in the chaco and in the tropics generally than in temperate North America. Most chaco species (252) are endemic in South America, but 28 percent reach Middle America, 12 percent attain North America, and 3 percent reach the Old World. A transatlantic distributional history is possible for as many as one-seventh the number of chaco species reaching North America. Only one species (Eudromia formosa) is endemic to the chaco; 11 others mainly occupy that area; five subspecies are endemic. Such low endemicity reflects the central location and accessibility of the chaco, and probably rather drastic historical changes in its extent and location. Major range disjunctions in chaco species and superspecies frequently involve northern South America, with Amazonia the apparent barrier. Isolates in the Andes and in the coastal Peru region are fewer, but well differentiated. The caatinga is another area of differentiation. Zones of avian interaction (70) and narrow range disjunctions (28) involving chaco birds show isolates and former isolates mainly in southeastern Brazil, in the campo-caatinga region, and in the Andes, indicating that barriers (e.g., grassland, water) exist or formerly existed between the paired forms. Significantly more nine-primaried oscines and fewer nonpasserine birds show interactions and narrow disjunctions compared with proportions of these species in the chaco avifauna. This perhaps reflects greater speciation and radiation in the nine-primaried oscines, a group still relatively new to southern South America. Primary intergradation in the 276 polytypic chaco species indicates the coincidence of racial borders with major environmental features such as the Amazon and Paraguay rivers, and with certain regions (campo cerrado, Andean base). Major size differences among races of 81 chaco species generally agree (69 cases) with Bergmann's Ecogeographic Rule, larger forms occurring south of smaller races. The chaco avifauna largely is derived from elsewhere, particularly from other xeric regions, savanna formations and edges or ecotones involving forested regions. The chaco nevertheless has been important in furthering range extension and the ultimate isolation of some xeric-adapted birds and species favoring edges and ecotones. There is a need for further in-depth taxonomic-zoogeographic investigations of particular Neotropical avian groups and regional South American zoogeographic analyses"--P. 167. en_US
dc.format.extent 53535790 bytes
dc.format.mimetype application/pdf
dc.language eng en_US
dc.language.iso en_US
dc.publisher New York : American Museum of Natural History en_US
dc.relation.ispartofseries Bulletin of the American Museum of Natural History ; v. 154, article 3 en_US
dc.subject.lcsh Birds -- Gran Chaco -- Geographical distribution. en_US
dc.subject.lcsh Birds -- South America -- Geographical distribution. en_US
dc.title A zoogeographic analysis of the South American chaco avifauna. Bulletin of the AMNH ; v. 154, article 3 en_US
dc.title.alternative Chaco avifauna en_US
dc.type text en_US

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  • Bulletin of the American Museum of Natural History
    The Bulletin, published continuously since 1881, consists of longer monographic volumes in the field of natural sciences relating to zoology, paleontology, and geology. Current numbers are published at irregular intervals. The Bulletin was originally a place to publish short papers, while longer works appeared in the Memoirs. However, in the 1920s, the Memoirs ceased and the Bulletin series began publishing longer papers. A new series, the Novitates , published short papers describing new forms.

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