Bummer...sorry to hear about your card. I have had cameras stolen too --- from private land! I often wonder if the culprits do this because they know they were 'caught' on camera. On private land this would make sense, I guess...because they could have been trespassing. Not sure about public though?
Thats great that he only took that. But what do expect? i think anyone who puts a trail cam in puplic woods is foolish. Its sad but its the truth. That would be like putting a nice pocket set in by a bridge. your just asking for johny sneekum to take your trap.
I hate to hear that. My guess is he was up to no good. I can't see any other reason for someone to only take the card, unless they plan on hunting that area and are letting you do the scouting for them.
FYI, covert cameras are pricey, but they have built in GPS that can be travked if stolen.