Have you made money off your original image, and as RDKirk asks, have you copyrighted your image? If you had your image filed for copyright, you might be able to seek legal action. But before, doing that, you have to ask yourself if it's worth pursuing financially: if your image can make you revenue and you're clearly losing revenue from the other person. RDKirk also brings up another point in that having a composite of a bald eagle on a landmark can be considered an easily conceived theme (and that the other artist might have thought of it also). If you try pursuing infringement to court, then you have to clearly show that it's a derivative work. Sometimes infringers just reflect an image the other way, or take your image and add something else. If this work is in a different style, and different composition, then it would be hard to show how they derived their work from yours. I have known artists that have had to spend a lot of time and money (years and thousands of dollars) taking print firms to court for directly copying their work. You need to weigh your options.
I have known animation firms decide not to do anything with an infringer since their original animation had made them a lot, and it was clear the derivative work (which had the exact same composition and animation but not rendered as well) was not making the infringer much to seek damages. If you just wanted an infringer to cease publishing their work, and you were sure they did copy from you, a common suggestion is to write them a letter with copy of your work and evidence of their work being derivative. Then kindly ask them to cease publication of their work.