The key to this puzzle is to notice that all the supplied words are synonyms of certain types of birds. This link is confirmed by the title Layers: We are looking at words with different layers of meaning, while birds themselves are layers (they lay eggs). Furthermore, the presentation in the form of a taxonomic tree suggests we are looking at a list of biological names.
Working out the bird-related synonyms to each word then, we get:
Next we need to work out what to do with these new words. It should be clear that the first three bird-words, corresponding to the top three words in the image, are terms used to describe golfing scores: A birdie is one under par, an eagle is two under par, and an albatross is three under par. We can then use these numbers to index into the words attached to each corresponding term, so taking the first letter of 'quail' (cower) since it's attached to 'shuttlecock' (birdie=1), then the second letter of 'duck' (avoid) since it's attached to 'US coin' (eagle=2), etc. These are highlighted in bold above.
Doing so in order gives the incomplete sentence QUOTH THE RAVEN, a partial quote from the famous Poe poem named after another bird, The Raven. It features the repeated line "Quoth the Raven, 'Nevermore.'", which gives us the solution.
|The answer is: nevermore|