The Warblers of North and South America. They are small, very active, brightly colored songsters with needlelike bills. Many flit and hop through foliage as they search for insects. Most have some yellow in their plumage. There are over 50 species widely spread across N. America. Because males are the most colorful and sing as they migrate in spring and during early summer, they are usually the easiest to know. The females are often pale versions of the males. Identifying fall warblers can be a challenge. Highly migratory.