Simplification: Animal signals like bird songs are costly in terms if time and vulnerability to predators but most discussed is the energy cost. The evidence gives rise to various interpretations
Main Idea: There is discussion on the Energy cost of birdsong
P2-
Simplification: Thomas’s experiment suggests a relationship between song rate and body reserves of male nightingales; when song rate is high they lose more mass overnight
Main Idea: Evidence suggests energy cost of singing in Male Nightingales
P3(I found it difficult)-
Simplification: There are other associated costs like metabolic cost, regulation cost which arise from building additional body reserves, activities in different surroundings. The metabolic cost may or may not be important but there is significant energy cost specially with birds like nightingales
Main Idea: There may be other costs but Energy cost is important