Search USGS⌕ Search

Geology topics

N.J. Scott

Publications and source records attributed to N.J. Scott.

At least 55 records · Page 3Linked to original sources
USGS1984

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

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.

Condor↗
USGS1984

Trimorphodon

Explore the source record for details and available documents.

Catalogue of American Amphibians and Reptiles↗
USGS1984

Trimorphodon biscutatus

Explore the source record for details and available documents.

Catalogue of American Amphibians and Reptiles↗
USGS1984

Trimorphodon tau

Explore the source record for details and available documents.

Catalogue of American Amphibians and Reptiles↗