International audience The avifauna of the Lamto area has been studied during a two year period. 263 species have been recorded and the habitat prefe rences, diet, breeding periodicity and fecundity of the major species studied. 43 % of the birds are forest species. Only very few of them are abundant, eight species accounting for half of the total numbers of birds counted. Migrants are numerous in the savanna ; one third of them are palearctic passerines, while local migrants are represented mainly by non-passerine families. 90 % of the species are more or less omnivorous, but all migrants show a distinct preference for insect food. Breeding occurs throughout the year : among the 124 commoner species, 62 % breed during the rains and 23 % during the dry season. Fecundity is low and the same female seldom reproduces twice during the year. Counts have been made regularly on a line-transect 12.5 km long and 40 m wide. Monthly variations of numbers and biomasses are given in tables V and VI. Contrary to the situation further North, seasonal variations are small in the forest-savanna mosaic. There are two peaks : the first one, from February to May, corres ponds to an intlux of northern migrants ; the second, from July to September, is attributable to the natural increase of sedentary species and an intlux of fruit-eaters. Minimum values are found in December, at the beginning of the dry season. The average yearly biomass of birds for the Lamto savanna is in the order of 1 kg/ha (fresh weight).