HOW DO DAUBENTON BATS, MYOTIS-DAUBENTONII , USE THEIR DAY ROOSTS

Daubenton's bats, Myotis daubentonii, in the area of the Rhinefalls (S witzerland) use up to seven day roosts. On an average, they change roo sts every second day. Some individuals visited two or more day roosts within 24 hours, others used exclusively the same day roost for more t han two weeks. Males change roosts twice as often as females. A newly used day roost is some 600 m away from the old roost. All day roosts i n a forest are connected with one another by individual roost changes. Such day roost networks are restricted to one forest. The never found roost networks with day roosts in different forests. Following rainy days, Daubenton's bats have a higher tendency to change roosts than af ter dry days. Our knowledge is too small for a functional description of day roosts of Daubenton's bats. We distinguish the following day ro ost types: Type A day-roosts have high animal numbers without much cha nge from day to day. These day roosts are favourite, based on the numb er of changes at these roosts. Their entrances are two to five m above the ground. Bat groups in Type A day-roosts vary during the hunting s eason. Type B day-roosts have entrances ten m or more above the ground . 30 to 100 individuals stay together in type B1 roosts. Group size ch anges daily. Only single animals or a few animals stay in Type B2 day- roosts, but they use these roosts exclusively for two or more weeks. T ype C day-roosts have entrances two to five m above the ground. The nu mber of bats slaying together is small, usually less than 15, quite of ten less than 6 animals. They stay longer in a Type C roost than in a Type A roost.