Relationship between life and death. inside, outside: No information about this but it is two different photographs put together to create a half skull, half face image. That heavily relates to the theme of inside, outside and in between.
There have been over 400 species if these little birds identified over north and South America. These birds get up to about cm in length, from their bill to tail. They can weigh anywhere from 2 and 20 grams. (A penny is grams)