From The Heretic Knowledge Vault
Carrier parrots are the medium by which player character Sister Rose, in her secondary role as "Major Rose Nuria-Lucas, Veracian Special Forces," communicates with her higher-ups when out on the road in the boonies of Veracia. Basically, they're equivalent to carrier pigeons, with the added feature that they can carry verbal messages as well as written ones. This is a handy little feature that allows them to transmit Secret-level information by voice, so that there are no written records that might lead to a security problem. From the parrots' point of view, however, it comes with a down side: after delivering a Secret message, the parrot proceeds to drop dead -- another security feature, since dead parrots tell no tales. Presumably they'd rather carry the unclassified messages that go in written form, but nobody asked them.
All manner of messages, classified and un, get passed in the game via this medium, helping to drive plot developments, etc. PC Brother Timothy, a recent addition to the Veracia-roaming entourage, has the misfortune to become attached to one of the parrots that shows up to deliver a classified message (regarding the mysterious Father Blaise and the late, not particularly lamented Sister Bree), not realizing that it's just a matter of time until the bird keels over. When it does so, he's crestfallen. Normally this would be no big deal, as the carrier parrots aren't exactly noted for their warmth and friendliness, quite the contrary in fact. However, this particular bird was just friendly enough to leave the good brother quite upset by its demise. Well, it's a hard world out there.