Fig. 1

Map with West African study sites in The Gambia, Senegal and Mali. The purpose of this map is to localize the four West African study sites. Traveling west from the Atlantic Ocean in Senegal, the first study site is Madina Fall (a peri-urban site in Thiès, Senegal) 70 km east of Dakar, which is indicated by an asterisk on the map for the name of the study site (Madina Fall). Gambissara in The Gambia is southeast of Madina Fall and 310 km east of Banjul at the eastern end (Upper River Region) of the Gambia River and is also marked by an asterisk. The two Mali study sites are both on the Niger River which flows to the east for 3360 km after leaving Bamako on its way to southeast Nigeria (Port Harcourt). Dangassa is 70 km south of Bamako in the savannah region of Mali and has extensive seasonal rainfall. In contrast, Dioro is 290 km northeast of Bamako in the much drier Sahelian region of Mali. As with Madina Fall and Gambissara, Dangassa and Dioro are also marked by asterisks