Why do some birds have brightly coloured feathers?

Brightly coloured feathers in birds often serve as a means of attracting mates or as a warning to predators. In species like peacocks, vibrant colours are a sign of good health and genetic fitness, making them appealing to potential mates. For other birds, like parrots, bright plumage helps them blend into colourful environments, such as tropical forests. Additionally, the colours result from pigments or structural changes in feathers, creating iridescence that enhances their visual impact in sunlight.