The bat detector is used to hear the echolocation signals to determine what bats are in the area. You can record their signals and
'make" them discernible as to what bats are around since their signals cannot be heard. It is interesting stuff.
Screw he fishing - lets talk about bats. I didn't catch any bats.
My brother in law works for Cascadia Research and is one of the local bat experts. He actually found the nursery colony under a pier at Woodward Bay in Olympia. He provided the bat detector. Who knows, it may even end up in the Oroville area.
It was interesting that a pair of peregrine falcons made a nest in a tree - which is unsual - by the colony, and they would hunt them at dusk when the females headed out for the night foraging. Too bad for the pups when mom didn't come back.
When I first moved to the Island I went to a Bat Seminar. The woman who put it on had a "bat detector" and we used it to find some in the area. I later looked into getting one but if I remember they were pretty pricey. We have a bat house I made up on the southern side of our roof. They come back every year and "hang out" until it gets cold. Most likely Small Browns as best I can tell. They migrate like some bird species. I have the the pieces for another bat house if your interested Rick.