Complex sentence: It has pointed wings and plumage that varies by season, the non-breeding plumage is typically white underneath with a black crown, nape, wings and back and an all over mottled brown barring in the breeding plumage.
Split into simpler sentences: It has pointed wings and plumage that varies by season. The non-breeding plumage is typically white underneath with a black crown, nape, wings and back, and an all-over mottled brown barring in the breeding plumage.