By trapping a bat in a mist net, one can find out
What kind of bat is it?
Is it male or female?
Is it pregnant and/or lactating?
Is it genetically related to other bats in the area? (take blood sample)
weighing a bat.
How much does it weigh?
Does its weight change?
(recapture various times)
How big is it?
What does a bat do all night long?
To find out, a tiny transmitter is attached to the body of the bat with surgical glue
Elisabeth Kalko following a bat
How much time does it spend looking for food?
How much time does it spend eating?
How much time does it spend sleeping?