About Anas diazi Ridgway, 1886
This bird, the Mexican duck (scientific name Anas diazi Ridgway, 1886), measures 51 to 56 cm in length. Both sexes resemble female mallards, but have slightly darker bodies. The species is mainly brown, with a blue speculum edged with white that is visible whether the bird is in flight or at rest. Males have bills that are a brighter yellow than those of females. Most of the Mexican duck population is non-migratory and resident, though some northern birds migrate south to Mexico during winter. The species is also widely present, but in low numbers, in Colorado across all seasons, and there are photographically documented records of birds identified as this taxon from Utah, Wyoming, Nebraska, and Montana. Mexican ducks inhabit most types of wetlands, including ponds and rivers. They typically feed by dabbling for plant food or grazing. They usually build nests on river banks, though nests are not always located particularly close to water.
