There is nothing about what is shown in this photo that says you need to put the bird down immediately without at least taking a closer look and assessing what is actually happening. 1st step is to take the bird and give her a good soak so that you can clean that area and very well visualize what you're dealing with. Prolapse is not an automatic reason to put them down as in many cases it can quite easily be corrected. Get the bird cleaned up and post some photos of the area at that point so we can help you determine what's going on and how best to proceed