The female peregrine falcon was seen early this evening perched somewhat forward at the nest ledge.  She was showing her silver federal leg band along with just a clear look at her bi-colored black over green (32/BC) leg bands.  It was mostly cloudy with winds at 10 MPH out of the north and the temperature around 77 degrees and moderate humidity.  She remained perched for over 30 minutes with moments of eye closing drowsiness. Peregrine Falcons can sleep with one eye open, as half of their brain is alert while the other is asleep. This is called unihemispheric slow-wave sleep (USWS) and it allows the sleeping falcon to spring into action quickly from rest if a threat approaches while still being able to satisfactorily rest if no threat arises!