There are many data regarding life tables and life expectancies of many
species of birds (e.g. see Birds of North America species accounts) .
There also are maximum gaes of birds determined from mark recapture
(e.g. a series of papers by Kathy Klimkiewicz of the Bird Banding
Laboratory, Patuxent, MD) in Journal of Field Ornithology some years
ago).

Birds do not scent mark with their bills as some mammals do in various
ways.