Mexican Duck Life History

Habitat

Mexican Ducks inhabit nearly all aquatic habitats—both natural and human-made—available in their semiarid-to-arid range. These include both permanent water bodies where they spend the lengthy dry season (lakes, reservoirs, and large streams) and seasonal water features where they breed (small reservoirs, farm ponds, temporary marshes, and intermittent streams).

Food

Mexican Ducks are largely vegetarian during the dry/nonbreeding season, which lasts from October to early June in Mexico. In many areas they feed in agricultural fields, where major food items include garbanzo beans, wheat, barley, and oats. In large wetlands, such as the Lerma marsh in the state of México, they feed largely on aquatic plant seeds, weed seeds, corn seeds, and aquatic plant tubers. It is thought that Mexican Ducks eat more invertebrates during the breeding season to provide protein for eggs and chicks.

Nesting

Nest Placement

Mexican Duck nests are very difficult to find, but the few known nests were generally placed on the ground among dense vegetation about 200 meters (650 feet) from the closest water.

Nest Description

Nest is a shallow cup lined with down feathers. A 2019 nest study from Guanajuato, Mexico, found the primary material for seven nests to be wheat stubble, with sorghum used as a secondary material.

Nesting Facts

Behavior

Mexican Ducks are monogamous, but there is little information about how long pair bonds last. These ducks breed during the rainy season from June to October, and then gather into large flocks that grow in size as the dry season progresses and small seasonal habitats dry up.

Conservation

The U.S. Fish and Wildlife Service listed Mexican Duck as an endangered species in 1967, due to a small population and habitat destruction in its limited U.S. range. However, the USFWS removed Mexican Duck from the Endangered Species List in 1978, after the duck was reclassified as a subspecies of Mallard.

Because Mexican Duck was lumped with Mallard for so long, neither Partners in Flight nor the International Union for Conservation of Nature currently have a conservation assessment for this species. The overall breeding population was estimated at 55,000 individuals in 1978, with 98% of the population occurring in Mexico. Much of the natural wetland habitat in Mexican Duck’s range has been destroyed, but the species has adapted to the new wetlands and reliable food sources provided by agricultural landscapes. A 2002 assessment of Mexican Duck population trends concluded that the species was not under any serious threat and had likely never been much more abundant than it currently is.

Credits

Baldassarre, G. (2014). Ducks, Geese, and Swans of North America. Fourth edition. Wildlife Management Institute, Washington, DC, USA.

Chesser, R. T., S. M. Billerman, K. J. Burns, C. Cicero, J. L. Dunn, A. W. Kratter, I. J. Lovette, N. A. Mason, P. C. Rasmussen, J. V. Remsen, Jr., D. F. Stotz, and K. Winker (2020). Check-list of North American Birds. American Ornithological Society. http://checklist.americanornithology.org/taxa

Colón-Quezada, D (2009). Composición de la dieta de otoño del pato mexicano (Anas diazi) en el vaso sur de las ciénegas del Lerma, Estado de México. Revista Mexicana de Biodiversidad 80: 193- 202, 2009.

Drilling, N., S. O. Williams III, R. D. Titman, and F. McKinney (2020). Mexican Duck (Anas diazi), version 1.0. In Birds of the World (P. G. Rodewald and B. K. Keeney, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.mexduc.01

Pérez-Arteaga, A., Monterrubio-Rico, T., Huacuz-Elías, D. C., & Herrerías-Diego, Y. (2019). Nidos y nidadas de pato mexicano (Anas diazi) en Pénjamo, Guanajuato, México. Acta Universitaria, 29, e1910. doi. http://doi.org/10.15174.au.2019.1910

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