Plumage Phases in Orioles Feathers are a bird's only protection from the elements, and they do not last forever. Because plumage wears out, birds periodically molt some or all of their feathers and grow new ones. When you try to identify a bird, it is important to be aware of this, because molting can cause birds to have different plumages at various ages and seasons. This is particularly true with orioles. This section explains how molts occur in orioles and is essential background for the identification information that follows.
All orioles are featherless when they first hatch, but they quickly grow a set of downy feathers.
These feathers are kept until late summer and fall, when the bird undergoes what is known as the first prebasic molt . The bird may molt just some body feathers, or it may molt all of its body feathers and some wing and tail feathers as well. What grows in afterward is called the first basic plumage . In the next spring, many orioles go through another variable molt, which again may include just some body feathers, or as much as all body feathers and some wing and tail feathers. This is called the first prealternate molt .