To create a custom list:
Find the bird you would like to add to a list
Tap on the bookmark icon
Tap on the "+" in the top right hand corner to create a new custom list
Name the new custom list and tap "Save"
Then tap on the custom list you just created and a checkmark will appear
Tap the "<" back button in the top left hand corner and it will navigate you back to the bird species page where the bookmark icon will be filled
To access your custom lists and add more species to the list:
Navigate to "My Audubon" in the bottom navigation menu
Tap on "My Custom Lists & Alerts"
Then tap on the custom list of your choice
To add more species to the custom list tap "+ Add Species to List"
Search or scroll to add more species and tap "Save" in the top right hand corner
The species added should appear in the custom list