Hero Arts; inks come from a variety of manufacturers.)
Learning bird calls can definitely enhance the enjoyment of your geocaching hunt (or your walk back to the car). Some other tools I use to memorize bird calls are mentioned in this post, where I identified a coot.
I recently saw a coot, identified by a bird expert, by attending a Meetup at Gray's Lake. While I love love love being outside alone and as a family, I also enjoy more social experiences.