Decorah Eagles, Ustream.TV: 1 Questions of the Week How soon can you tell if they are male or female? Humans won't be able to tell gender unless a blood t... An adult is at the nest right now but the nestlings are old enough that the parents leave them alone for longer periods of time. The camera operator will often zoom in on tiny details and this morning, I notice they're getting their first blood (flight) feathers. I used to work with raptors so enjoy leaving this up to watch off and on if I'm at my desk. Hope you all enjoy.