Acta Biotheoretica

, Volume 19, Issue 1, pp 37–44 | Cite as

On territorial behavior and other factors influencing habitat distribution in birds

II. Sex ratio variation in the Dickcissel (Spiza americana Gmel)
  • Stephen Dewitt Fretwell
  • James Stevan Calver


This example is provided so that non-theorists may see actual applications of the theory previously described. The Dickcissel sex ratio is employed as an indirect index of suitability. A sex ratio index was found to be correlated positively with density. This is consistent with the hypothesis that territorial behavior in the males of this species limits their density. This study provides a valid example of how the problem can be approached and offers a first step in the eventual identification of the role of territorial behavior in the habitat distribution of a common species.


Common Species Eventual Identification Actual Application Territorial Behavior Ratio Index 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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  1. Graber, R. R. &J. W. Graber (1963). A comparative study of bird populations in Illinois. 1906–1909 and 1956–1958. - Illinois Natural History Survey Bulletin, 28, Article 3, 302–328.Google Scholar
  2. Zimmerman, J. L. (1966). Polygyny in the Dickcissel. - Auk, 83, 534–546.Google Scholar

Copyright information

© E. J. Brill 1969

Authors and Affiliations

  • Stephen Dewitt Fretwell
    • 1
  • James Stevan Calver
    • 1
  1. 1.Biomathematics Program, Department of Experimental StatisticsNorth Carolina State UniversityRaleighUSA

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