Why is my conures droppings have blood in them?

His food has some red color? If you have not seen any major signs of adverse health in him (such as acting lethargic/tired/forcing himself to molt) then it may be worth it to hold off on the vet trip and see if its a dye on the seeds, not him bleeding. Change his food to something without the red seeds and pellets and see how he 'goes' in a couple of days.