I understand your logistical constraints. The toe you're referring to is not uncommonly injured. Green Lantern's toe was traumatized to the point that the vascular supply to it was interrupted. Dry gangrene, then, arose resulting in the necrosis (tissue death) you're now seeing. You don't need to do anything because I expect it to fall off at some point and there shouldn't be any bleeding associated with that happening.
I do want to talk to you a little about their diet because nutritional imbalances are a common cause of illness in our pet birds. What has your birds' diet consisted of, please? Seeds should compose less than 20% of their diet. Ideally, a balanced pelleted diet such as can be found here: www.harrisonsbirdfoods.com or here: www.lafeber.com/pet-birds should be fed as well as hard boiled egg yolk, pancakes and cornbread, the tops of fresh greens, dairy products such as yogurt and cheese, fresh fruits such as apples, pears, melon, kiwi, and berries, vegetables such as broccoli, carrots, beets, asparagus, cabbage, sweet potato, and squash, and even tiny pieces of meat.
Please respond with further questions or concerns if you wish.