gosh you sure are right, the birds do hide symptoms so we need to be extra watchful all the time, my parrot did get sick here in monsoon season a few times many years ago with a cold like thing , he was never sick for all the 42 years i had him , but during monsoon a few time he got this cold thing , so i called the local zoo in Douglas, they sold me an antibiotic, , and told me that all their birds & reptiles were all coming down this this cold like thing to..? , but that antibiotic only worked that year and it came back , so since i dont like drugs , i decided to feed my BURT raw garlic , he loves it any way & i also gave him some raw ginger root , and that has kept him well for the last 5 years , and thank goodness for that since we don't have any bird vets around here.! so that took care of that.