Lists
The Birds of Panama: A Field Guide by George R. Angehr and Robert Dean (Illustrator) has a useful checklist.
The Avibase Checklist section. Select country and taxonomy source (I use Clements latest Edition).
The Audubon Panama Website has a good complete list of Panama Birds at this download PDF link.
The Wikipedia List of Birds of Panama is useful to find information about specific birds.
A complete list of All the birds featured in my 1 hour YouTube video Some Panama Birds.
Birders Building Lists
Following birders I quickly learned that what they are really up to is collecting birds to add to their lists. They love to make long lists of all the birds they have seen for the day and during their lifetime.
These 3 guys are some of the best birders I have ever known and they have very long lists but they mostly love to find birds and are very good at it. In the photo they were looking at some type of warbler about a half mile away and arguing over which one it was!
My wife is a bidrder and a lister. In fact, she has a very long list of things I need to get done for her! It is longer than her birding list.