Say ye've been picking through a standing flock of gulls for an hour or two and then took a photo of them, for what ever reason.
A week later, ye showing this shot to a friend when he gasps and blurts out;
" OMG! Look at the secondary's on that one ~ third from the left. Two lines down! That's a Larus catcharat! Mongolian Spratgobbler Herring Gull! It's a MEGA for East Slough!!! "
What do ye do? It is Indeed a catcharat. It's a First. You'd obviously have laid eyes on it that day, because ye eyeballed every bird in that group ~ even if ye didn't happen to suss what it was ..... Now ye have enough evidence for it to sail past the BBRC. It's rock solid. The bird was there. Ye even have the local branch of Etams, clearly visible in the background, clinching the location.
Moral dilemma: Do ye Tick it?