How about...
put an *active* RFID tag on the bird (the active ones have a big range, like 100m) and set up readers around the Garden (and elsewhere). No need to rely on unreliable humans to do the bird-spotting.
Sydney’s Royal Botanical Garden is using Facebook to track its population of sulphur-crested cockatoos. John Martin, Wildlife Officer at the Garden and Ph.D candidate at the University of Wollongong, explained to The Register that he hopes to study the birds, which are infamously loud and destructive, the better to understand …