MEXICAN DUCK Anas diazi (Ridgway) 



Order: ANSERIFORMES Family: ANATIDAE 



Distinguishing characteristics : A large dabbling duck, most closely resembling the 

 black duck but lighter colored and with white-bordered speculum like a female mallard. 



Present distribution : Extremely localized in southeastern Arizona, southern New Mexico 

 and central western Texas, south in Mexican Highlands to Puebla and Michoacan. 



Former distribution : Same , and farther north in the Rio Grande Valley to northern 

 New Mexico . 



Status : Extremely vulnerable although it still has a fairly large population in Mexico. 



Estimated numbers : Possibly 500 in the United States; 14,760 in Mexico according to 

 "Winter Surveys January 1970" in Mexico Winter Waterfowl Survey of Bureau of Sport 

 Fisheries and Wildlife . 



Breeding rate in the wild : Five to seven young . 



Reasons for decline : Drainage of wetlands. Also hybridization with the common mallard 

 (Anas platyrhynchos ) is taking place with the southward spread of this species. This 

 may be a result of changing remaining wetlands to a condition more suitable to the mallard 

 than to the Mexican duck. 



Protective measures already taken : The New Mexico Department of Game and Fish and 

 Bureau of Sport Fisheries and Wildlife are developing habitat on refuges and conducting 

 captive propagation. From progeny obtained by captive rearing, breeding pairs have 

 been distributed to New Mexico State game farms, refuges, zoos, and private propagators. 

 Restocking of former breeding areas has begun. Penned flock of brood stock established 

 at Bosque del Apache National Wildlife Refuge in 1965. Habitat is being restored at 

 San Simon Cienega by Bureau of Land Management. 



Measures proposed : Research to determine if there is a specific type of habitat required 

 by Mexican ducks, distinct from that required by mallards, which may separate the 

 forms reproductively . Reestablishment and protection of suitable habitat in the former 

 breeding areas; restocking suitable habitat with pure strain birds reared in captivity. 



Number in captivity : Present number unknown. Mostly in possession of private 

 propagators . 



Breeding potential in captivity : Good . 



References : 



Aldrich, J. W. and K. P. Baer. 1970. Status and speciation in the Mexican duck 



(Anas diazi ), Wilson Bulletin, 82:63-73. 

 Huey, W. S. 1960. Restoration of the New Mexican duck. December job completion 

 report. Federal Aid Project No. W-91-R-3, Job No. 9. New Mexico Department 

 of Game and Fish. 10 pp. 



. 1963. New Mexican duck's return. New Mexico Wildlife 8(2): 18-19. 



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