Elder roostros are the senior-aged roostros who have retired from the otherwise bustling life of their younger counterparts. 'Young roostros crow too much, they move too fast, and frankly have no respect for their elders,' an elder roostro might say of youths; as they make a gross, smacking sound with their lips. Though this is of course impossible, as roostros do not have lips.
An elder roostro can no longer sire chickadoos and serves no other purpose than becoming a slightly tough chicken dinner.