Habitat: Black-bellied whistling ducks (tree ducks) are found regularly in southern Texas and erratically elsewhere. Open woodlands, groves or thicket borders where ebony, mesquite, retama, huisache, and several species of cacti are dominant in freshwater habitat are preferred (Oberholser 1974, Meanley and Meanley 1958). Range extensions have been facilitated by flooding and impoundments. Nest: Natural cavities in trees such as live oaks, ebony, willow, mesquite, and hackberry are preferred, but ground nests and nest boxes are sometimes used. The nest can be over land or water, but herbaceous vegetation under “land-bound” nests may be preferred to brush (Bolen et al. 1964). A perch near the cavity entrance may also be a factor in nest tree selection. Open and closed cavities are used. Nest cavities average 8.7 feet above ground or water and 23 inches deep, with 7.0 × 12.5 inch openings (Bellrose 1976). Nesting boxes should be 11 × 11 × 22 inches high at the front and tapered to 20 inches in the rear, with entrances 5 inches in diameter (Bolen 1967). Nest boxes should not be erected unless they are predator proof. Food: Black-bellied whistling ducks are predominantly grazers (Rylander and Bolen 1974), but they can dabble and dive for aquatic food. Of 92 percent plant materials, sorghum and Bermudagrass predominated, with smartweeds, millets, water stargrass, and corn also occurring in one study (Bolen and Forsyth 1967). In some areas corn and oats are more important in the diet. Wood duck _Aix sponsa_ L 13½″ W 28″ [Illustration] Habitat: Wood ducks are associated with bottomland hardwood forests where trees are large enough to provide nesting cavities and where water areas provide food and cover requirements (McGilvrey 1968). Requirements may be met in several important forest types, all of which must be flooded during the early nesting season: (1) southern flood plain, (2) red maple, (3) central flood plain, (4) temporarily flooded oak-hickory, and (5) northern bottomland hardwoods. Nest: Optimum natural cavities are 20 to 50 feet above the ground with entrance holes of 4 inches in diameter, cavity depths of 2 feet, and cavity bottoms measuring 10 × 10 inches (McGilvrey 1968). Management for cavities more than a half mile from water is not recommended, and dead trees, other than cypress, do not usually contain usable cavities. Good densities of suitable wood-duck cavities have been recorded for many timber types (Bellrose 1976). Nest boxes are readily used by wood ducks, and their use may increase breeding populations, even if natural cavities are abundant, if predators are excluded. Measurements and placement of wood duck boxes have been well described (U.S. Fish and Wildlife Service 1976, Bellrose 1976, McGilvrey 1968).