A very interesting activity we did this summer in Sweden was a "bat Safari".
The safari goal was, after making a mini lecture on these exciting, unknown and harmless animals, walking in search of bats of different species and customs.
The instruments that we had was a flashlight to see the road and especially an ultrasonic sound transducer, bats emit to navigate and hunt sounds impercetibles ultrasonic and therefore for us, these devices can translate into audible inaudible frequencies, so we can hear the funny noises these animals emit!. Each species makes a different noise characteristic. Here you can hear some sounds as they are heard with this gadget
The tour was organized by Pelles Viltsafari, in their page you can find information if you are interested in doing this or other animal safaris in the Swedish nature