The use of dams by the Mexican duck (Anas diazi Ridway, 1886) was documented between September 1994 and March 1995, in the region of El Llano, located in Mexico between Aguascalientes and Jalisco. The objective of this study was to determine which type of dam is more frequently used by this species, based on a use-availability water analyses. The results point out a superior use than expected of the reservoirs used as water storage which are pumped for irrigation, throughout fall and part of winter. These dams can be vital for the breeding of ducklings in Mexico. The identification and evaluation of the dams which are more frequently used by the Mexican duck will allow developing strategies for their conservation and sustainable use.
