I bought a book on Birds for imagery and chose a couple to illustrate from. The black one on top is called an American Redstart (Found in North America, obviously) and the yellow one is called an American Yellow Warbler.
I have been wanting to get back in to illustrating and birds have always been a common theme for me in my work. They come in so many shapes, sizes and colors. You see them everywhere, not just in person, but on clothing, company logos, tattoos, accessories, etc.