Flag unlikely birds against the known distribution of the bird
Bird Journal does many things that eBird and associated apps can't do. That's the brilliance of Bird Journal! However, a critical problem with Bird Journal is that it let you record that you saw a Siberian Jay in Central Australia. The data that Bird Journal holds contains the distribution of birds according to users. I think Bird Journal needs to use this to flag to users, "Are you sure?" If someone says, "Yes!" to seeing a Siberian Jay in Central Australia, then that observation can easily be ignored as an outlier until sufficient user sighting have to received to varify a very unlikely population of the species has made the brave move to emigrate to Australia! This doesn't require moderators. It can be based purely on statistical likelihood.