Three, Two, Then One
An eyass died over the last few days at St. John the Divine, and it looks like we have only a single surviving eyass. The remains of the second eyass are visible at the front of the nest. The parents will remove the eyass after a few days.
Some hawk watchers have suggested removing the eyass to have it tested. However, with two healthy parents and a difficult location, this seems to be impractical. There is the danger that the healthy eyass might prematurely fledge and be injured if the nest is approached. This is also the possibility that anyone who attempts to remove the dead eyass will be attacked by the parents. Either the rehabber or the parents could be injured if this happens! Furthermore, unless the cause of death was obviously frounce (a disease caught from pigeons), any test results would take too long to aid in the treatment of the surviving eyass.
So, the best course of action in this case, seems to be no action.