A researcher recently filmed 5 Indian peacocks to work out what price male birds pay for carrying the magnificent plumage they use to display in order to attract females and found that it doesn't slow them down during flight.
The spectacular iridescent feathers they use might not be quite the sacrifice to love that it appears to be.
Dr Graham Askew, from the University's School of Biomedical Sciences, said that these feathers weigh about 300g and can exceed 1.5m, so it's expected that the male birds would be making a significant sacrifice in their flight performance for being attractive, possibly giving up their lives if the train restricts escape from predators such as tigers and leopards in their natural environment.
Researcher filmed the take-offs of birds carrying full plumage in 3D, and then filmed the same birds taking off without their trains. The display feathers, which naturally moult at the end of the breeding season, were cropped to judge the change in take-off performance between the two states. But he found there was no significant difference.
The position of each bird's centre of mass was observed, their wing motions and the movement of the train in take-off and then calculated the amount of power used by the birds to accelerate and gain height over the first two wing beats and found that it was essentially the same, regardless of the presence or absence of the train.
The research also looked at how much drag the train created during take-off by mounting a detached train in a wind tunnel. Although the drag doubled, overcoming that drag is only a tiny part of the power used by the birds during take-off. Therefore, the impact of the train on the overall take-off performance is negligible, allowing birds with and without trains to invest the same amount of power in the ascent.
The results do not mean that having an ornate train carries no costs for peacocks. Dr Askew pointed out that the feathers might adversely affect flight stability and the birds' ability to run. Just creating the ornate plumage was a costly exercise; male birds invest about 3 percent of their daily metabolic energy budget in train growth.
