Orange-crowned Warblers are a hard bird to identify because most of the time you can’t even see their orange crown. They usually look all gray to olive green colored. They have virtually no markings… Just a black stripe through the eye and a small white area above, but even this is not always very well defined. They have a thin bill and are about the size of a chickadee (or a little shorter).
So if you have a small gray or green mystery bird visiting your suet feeders, you may consider that he’s an Orange-crowned Warbler. They are also more common in the west than the east, so if you live in Washington State like me, you might be more likely to see them. The ones I’ve seen are always solitary. And hungry for suet!