“a hundred days of sermonizing, one fart” → a metaphor for how something that one has put great effort into can come to nothing after even a slight mistake, much as a hundred days of serious spiritual study can be lost to the winds

kill two birds with one stone, do one task and finish two or more goals (literally, “one stone, two birds”)

an Atlantic puffin

(idiomatic) in the land of the blind, the one-eyed man is king

a northern cassowary (Casuarius unappendiculatus)