Yellow-billed storks, Congo (Democratic Republic)

Yellow-billed storks make irregular migratory, partially migratory or nomadic movements within Africa to areas where changing water levels increase fish availability. Some populations are also largely sedentary. Breeding is seasonal and starts whenever food is most abundant according to local ecological conditions (e.g. when fish become concentrated in small wetlands or marshes), this may either be towards the end of the rains or during the dry season. The species breeds colonially, often with other species, usually in small groups of 10-20 pairs. It is a gregarious species but never aggregates into very large flocks, being more often observed in pairs or small flocks of up to 50 individuals. At night it forms communal roosts in favoured roosting sites (e.g. sandbanks or trees), which may attract individuals from a wide area. The species inhabits a variety of wetlands with shallow water 10-40 cm deep for feeding and sandbanks or trees for roosting. It frequents large swamps, the margins of rivers and lakes, lagoons, large marshes, small pools, flooded grassland, alkaline lakes, reservoirs, waterholes and rice-paddies. The species generally avoids areas of large-scale flooding and is rare in forested areas (although it may occur in wooded savanna). Its diet consists of small aquatic prey such as frogs, small fish, aquatic insects, worms, crustaceans and occasionally small mammals and birds. The nest is constructed of sticks and is positioned in small trees over water or high up in larger trees on dry land. The species nests colonially in single- or mixed-species groups with up to 10-20 pairs per tree, neighbouring nests usually spaced 1-3 m apart. This photograph was taken when Eliot Elisofon traveled to Africa from early March 1951 to July 1951.