my guess is that it went up in there looking for a place for a nest. and then it saw the quarters, i've heard that birds like shiny things, my birds used to love playin with a small mirror.
How would it be shiny though? is there a light up in therrrr...? no... so the quarters would be dark, not shiny?? maybe they saw a human grab quarters out of there and drop one so they new it was shiny and then got an idea to go up in there and search around for the shiny objects...