Male peacocks have tail feathers that make up about 60% of their body length. During the mating season they shake these feathers in front of females. Longer feathers produce a larger volume of rustling sound for a given shaking rate, but they are also heavier, and thus require more energy to shake at a given rate than shorter feathers. This suggests that:

Question

Quizplus · Accepted Answer

There are conflicting selective pressures on peacock tail feather length - longer feathers produce a larger volume of rustling sound but require more energy to shake, while shorter feathers require less energy to shake but produce a smaller volume of sound. This suggests that there is a balance or compromise between these two selective pressures, resulting in an intermediate feather length that is optimal for attracting mates while minimizing energy expenditure. Therefore, selective pressures will not always result in longer or shorter tails, but rather a balance between the two pressures.

Male Peacocks Have Tail Feathers That Make Up About 60