Observations about Rhynchonycteris naso and Noctilio albiventris were carried out in the Jaíba region, northern Minas Gerais State, Brazil. Colonies of these bats were found in association with watercourses in areas under considerable antropic influence. The night activity of both species began about half an hour after sunset during approximately one hour. A second period of activity was noted in R. naso, and in the majority of N. albiventris. These bats used temporary night roosts, observing formation of clusters in the later. Capture, with mistnets, of lactating females in April and October suggest that in this area both species present a bimodal poliestric reproductive pattern, with peaks of births at the beginning and the end of wet season (October to March). The occurrence in sympatry of these species must be facilitated by the greater opportunism of N. albiventris in relation to the foraging areas and due to its capacity of exploring aquatic insects.
Chiroptera; Rhynchonycteris naso; Noctilio albiventris; activity pattern; reproduction
