As many people have pointed out by now, there is a bug in Birdfeed 1.0’s multiple accounts support. If the username you specified when signing up for Twitter has uppercase letters in it (e.g. “BirdFeedUser”), Birdfeed will consistently forget that account and require you to login again on relaunch. This is the result of a boneheaded coding error that unfortunately we didn’t catch pre-launch because, apparently, no one out of the 50 or so people in our beta has uppercase letters in their username. D’oh.
Unfortunately, the only workaround to this problem currently is to change your Twitter username to all lowercase. To do so, go to the “Settings” link in the bar at the top of your Twitter account, then change the name listed in the “Username” field to all lowercase. Once this is done, try logging into Birdfeed again and everything should be fine.
We sincerely apologize for our error and the resulting confusion. We plan to have a 1.0.1 update that fixes this problem submitted to Apple very soon.
Update: If you still are having problems after following the above steps, you will need to delete Birdfeed off your phone, re-download it (which will be free if you already bought the app), and then log in with your lowercase username. Once again, we realize how much this sucks. Fortunately we already have a fix ready to submit. Apologies, and many thanks for your patience.
Update 2: Birdfeed 1.0.1 is out, and it fixes the Account Amnesia problem. -Neven