If it's very hot where you are then the runny droppings could be from drinking a lot of water trying to stay cool. Lots of things can cause runny droppings, it may or may not be something to worry about. If she's laying, eating, drinking, acting normally, then if you can get a fecal float test done, that will check for internal parasites. Alternately you could just worm her (it's very safe) and see if it helps clear it up. Internal parasites are much more common that many people realize, they are constantly digging up and eating things off the ground, and you will most often not every see anything in a dropping. Runny or mucousy dropping, or increased intestinal shed in the droppings can be an indication of parasites. I would try to clean her up if it's real messy, particularly if you have flies. If flies find her they can lay eggs in the droppings built up around the vent feathers, and when they hatch the larvae (maggots) will feed on the live bird. That is called fly strike and it's life threatening. If she's chronically dirty back there you can trim the feathers back with a small pair of scissors to help keep it from getting as bad.
