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Phenotypic variation of the Mexican duck (Anas platyrhynchos diazi) in Mexico

Condor

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Abstract

A collection of 98 breeding Mexican Ducks (Anas platyrhynchos diazi) was made in Mexico from six areas between the United States border with Chihuahua and Lake Chapala, Jalisco, in order to study geographic variation. Plumage indices showed a relatively smooth clinal change from north to south; northern populations were most influenced by the Northern Mallard (A. platyrhynchos) phenotype. Measurements of total, wing, and culmen lengths and bill width were usually significantly larger in males at any one site, but showed no regular geographic trends. Hybridization between platyrhynchos and diazi phenotypes may or may not be increasing in the middle Rio Grande and Rio Conchos valleys; available data are insufficient to decide. A spring 1978 aerial census yielded an estimate of 55,500 diazi -like birds in Mexico. Populations of diazi appear to be as large as the available habitat allows; management should be directed towards increasing and stabilizing the nesting habitat; and the stability of the zone of intergradation should be investigated.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Phenotypic variation of the Mexican duck (Anas platyrhynchos diazi) in Mexico
Series title:
Condor
Volume
86
Issue:
3
Year Published:
1984
Language:
English
Contributing office(s):
Patuxent Wildlife Research Center
Description:
266-274
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Condor
First page:
266
Last page:
274
Number of Pages:
9