2 bats, flying, Gålö

Date of Observation
Sighting Details
What did you observe?
Other (What did you Observe)
One larger and one smaller bat. Flying. During dusk. Period about 45min. At least 2 bats, One significantly larger compared to the other one. (Did not see them in the air together).
Can you give further details on the observation e.g. behavior, habitat etc:

2 bats flying. Hunting? During a 40 min period. 

How many bats did you see?
2-10
How did you identify them
Visually Identified Bat