Organize and transfer files using proprietary PC software

(iTunes, Sony SonicStage, etc) or simple drag and drop from your PC?

The proprietary software lets you organize and retrieve files using
three or four tags.  While these have labels like "genre, "artist
name," and "song," you can use them to categorize bird song by genus,
species, subspecies, location, and date.

Simple drag and drop organizes alphabetically by file name.  This
works OK, but it will probably require a separate printed list to help
you decide which file you want to play.  Also, some MP3 players limit
the number of directories, and files in a directory.