In May, the first cygnets of the year begin to hatch. The mute swan, the most common swan in the UK, will incubate its clutch of four to 10 eggs for up to six weeks. When they emerge, the cygnets weigh just 7-11oz (200-300g). They have a charcoal-coloured bill and feet, and their downy plumage is white or dove grey, sometimes with a faint rusty tinge. Within 24 hours, cygnets are able to leave the nest and are encouraged into the water, where they quickly learn to dive and swim. Here, they are safer from mammalian predators, and within two weeks, they are able to feed themselves on a protein-rich diet of insects and crustaceans. When fully fledged at 2-3 months old, they will have switched to their adult, plant-based diet and will weigh approximately 18lb (8kg); half their adult weight. They will retain their mottled grey and white colouring through the juvenile phase. Though now able to fly, the cygnets will stay close to their parents until the following spring, when they are chased away so that the parents can begin the nesting and breeding process again.