If  you enter zero (0) for a sighting E-bird assumes the species was 
present and shows it as an X in the summary table. This happened with marsh 
wrens at Hughes Hollow yesterday.  If you answer the question at the start 
of data entry Are you reporting all species seen as Yes then if the species 
isn't on the list then as far as you are concerned it wasn't present.
       BTW I didn't see the Snowy Egret at Hughes Hollow this am.  There was 
only one Great Egret.

Paul Woodward
Fairfax City, VA