Stupid Cowbird

I found out today that the one spotted egg in my nest was a cowbird egg. Some lazy mama bird ditched her egg in my nest and is relying on this other bird with her 5 eggs to take care of it for her. Of course, it hatched first, is the biggest, and now will possibly cause the other hatchlings to die. Which of course might explain why there are only 4 or 5 birds instead of 6. I am seriously bummed out about this. I don't know if I should/am legally allowed to take out the bird (apparently it may be protected by some bird act) but I don't want it to force the other birds to die either. I will probably choose to let nature take its course. Even if I could remove the bird, I don't want to touch it in any way, and I feel bad getting rid of one bird even to let other birds live. I was reading a little bit about them and in some ways they are kindof cool (like how they are genetically programmed to be cowbirds, they don't learn how to be that specific kind of bird because they don't have anyone to teach it to them, yet they act distinctly as their own species despite being raised by other ones) but it's just sad that the other birds might die because of it. Like I said, I will probably just let nature take its course.