Figure 3.

Box plots of (a) # unit types per year, (b) # themes per year, and (c) song duration (s) per year. Plots represent all songs in each year to show the variability per year (table 1). 2004 had two song types present: the Blue song type was recorded at the start of the season (2004a: Blue box plot); all other recordings that year were of the Dark Red revolutionary song type (2004b: Dark Red box plot).