Well I'll be.

At least two of the authors are also avid chiropterologists, with an understood penchant for bunkers and other such spaces.

One summer in my late teens I sat with two of them in an urban park in NW Poland drinking beer, watching bats getting caught in a net half-submerged in water near a bridge and engaging in impromptu comedy with passers-by asking questions like "good catch? any fish?". Good times.

Engaging in field research is a wonderfully rewarding experience, a great way to spend time, meet people and do something meaningful at the same time. If you've never done it - do it. There are plenty of volunteering opportunities - you don't need to be a scientist. Birding, insects, marine life, whatever. Citizen science is also great, but if you get a chance to work alongside scientists, it gets even better. 10/10 good walk, unspoilt.