The Paraguay River divides the Republic of Paraguay into two distinct regions: the Chaco to the west and the Orient to the east. The relatively flat Chaco is characterized by thorn scrub forests in the west, sub humid forests in the northeast and palm savannas in the southeast. The topographically diverse Orient is characterized by campos cerrados in the northeast, savannas in the west and southwest, and humid forests elsewhere. Paraguay's climate is subtropical, with rainfall increasing roughly fourfold from west to east.

Previous studies of the birds of Paraguay have focused primarily on the distribution and taxonomy of resident species. There have been no thorough reviews of the country's avifauna since 1940. This dissertation summarizes the status and distribution of the birds of Paraguay, documents patterns of bird distribution, and attempts to analyze the factors affecting bird distribution in Paraguay. It is based on a review of the literature, examination of specimens in major American museums, and extensive field work in Paraguay during 1987-1989.

The avifauna of Paraguay includes 641 species. An annotated checklist summarizes the status, habitats and relative abundance of each species in seven geographical regions. Distributional notes are provided for the more unusual bird records and taxonomic notes are provided for species represented by two or more forms in Paraguay that may represent distinct species.

Species richness in Paraguay increases from west to east. Faunal similarity between regions is best explained by habitat similarity, with the avifauna of the Chaco-like southwestern Orient being more similar to that of Chaco regions than to other Orient regions. The avifauna of each region has high affinities with adjacent areas of South America. No species is endemic to Paraguay. The forestsavanna transition, which roughly coincides with the upper Paraguay River but shifts eastward in the southern Orient, appears to be the most effective barrier to bird dispersal in Paraguay. There is little evidence that the relatively broad Paraguay River is an effective dispersal barrier. The Pilcomayo River likely formed a forest bridge between Yungas and Paranense forests.during more humid interglacial periods, and subdivided the Chaco avifauna.

LLU Discipline





Graduate School

First Advisor

H. Thomas Goodwin

Second Advisor

Leonard R. Brand

Third Advisor

Ronald L. Carter

Fourth Advisor

David L. Cowles

Fifth Advisor

L. James Gibson

Degree Name

Doctor of Philosophy (PhD)

Degree Level


Year Degree Awarded


Date (Title Page)




Library of Congress/MESH Subject Headings

Birds -- South America -- Paraguay; Birds -- Research -- South America -- Paraguay; Birds -- Geographical distribution; Birds -- Nomenclature (Popular)



Page Count

x; 415

Digital Format


Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.


Loma Linda University Electronic Theses and Dissertations

Collection Website



Loma Linda University. Del E. Webb Memorial Library. University Archives

Included in

Biology Commons