One of the main factors that make the chirping lethal is that it intermittently interrupts the afflicted's thought process. Patients have been observed to frequently walk out of bed, mumbling that the Bird is calling them, only to return right after. This often obstructs them from getting the rest and treatment they need. There is no known way to prevent this at the moment other than incapacitating the afflicted, so minimizing the length of the chirping becomes crucial.
Third, the Bird's influence is spreading very slowly throughout the planet. It will take approximately three years for it to devour all life at the observed rate, and for some odd reason it seems to not affect humanlikes at the moment. However, one of the colony seers felt something ominous growing within the Bird. It seems that it will reach maturity within roughly twenty days. It must be eradicated before then.
Though the seer's prediction brought a deep sense of dread, knowing that they are capable of doing noticeable damage to their archnemesis has put the colony's morale at an all-time high. From here on, it's a race against time.