Movement patterns and breeding characteristics of Arid Zone ducks.
Most arid zone ducks are nomadic or display a combination of movement patterns. Arid zone ducks that breed in the southern hemisphere (but not those that breed in the northern hemisphere) lay in more months of the year than do non-arid zone ducks. Clutch sizes of ducks that breed in dry environments are higher than those of sedentary ducks that nest in mesic lands, and similar to clutch sizes of migratory ducks that breed in non-arid habitats. Durations of incubation and fledging in arid zone ducks approximate those of sedentary species, but exceed those of annually migratory anatids that breed in mesic lands. Thus, incubation and fledging times in waterfowl that nest in arid country do not conform with the brief periods of flooding of many wetlands in these low rainfall areas.
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