Seventy-six percent of the bird species I've seen in North America I found myself. Maybe not the first sighting, but eventually.
What does that mean? Not much really. It's a quirk, which my Apple dictionary defines as a peculiar behavioral habit. I suppose that refers to keeping such a thing, a self-found list.
A few hundred more species were seen at the end of a guide's pointed finger. Not quite the same.
I have a booklet from the American Birding Association (ABA) titled "Birds of the Continental United States and Canada." It's a fat checklist. The ABA is mostly about lists. It publishes a fine magazine devoted to helping you find and/or identify birds for your lists.
When actively keeping that list up to date I marked the year and sometimes the state or province where I saw the bird. The list is a scrapbook, an album, a home movie, a box of slides, a memory jog to decades of unforgettable (for me) stories.
For instance, Antillean nighthawk, May 2003, Florida. My wife, Jude, and I are at the Key West airport with a birding friend and her non-birding husband. The nighthawks were circling high above the far side of the fenced grounds, identified by their faint but distinct calls. It was a target bird on that trip, a lifer for all of us, seen not an hour after an Englishman, working on his lists, kindly showed us our first mangrove cuckoo.
I can see those nighthawks as I type, bright day in Key West.
Razorbill, New Brunswick, Canada, 1992, flying over the harbor. I was on a business trip, taking my usual business-trip break to look for local birds. It looked like a football with wings.