When viewing checklists from other birders, checklists that the eBirder has opted to hide will display this message:
Hidden checklist. This checklist has been hidden from public view by the owner of the checklist: this checklist and its observations are only visible to the checklist owner and do not appear in public eBird outputs. More information.
Any eBirder can "hide" their own checklists from public view via the Hide/Unhide button on the right side of any checklist as viewed on ebird.org. Hidden checklists do not appear in any public output (including scientific use) and are not reviewed by eBird reviewers. In order for them to be scientifically useful, they need to be Unhidden and reviewed by eBird editors. If applicable, we encourage users to Unhide checklists after the reason for using the Hide Checklist option has passed.
Checklists that do not appear in public eBird output are also not used for science. To learn more please see our Public and Non-public Checklists for more information on how checklists are displayed.