______________ have less distinct plumage until they reach adulthood.

The correct answer is: Immature birds

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• Immature birds are those which are not properly developed
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• These birds are called sub-adult birds
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• The maturation takes place in these birds very lately
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• Raptors and gulls are classic examples of birds which mature late
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• The color of plumage appears less distinct and grows slowly
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• Understanding bird plumages: 
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