It's time to talk to her about this, and yes, this is disgusting. Such as, "I don't mind them in the living room so long as the poop is cleaned promptly and with an actual cleaner or in your bedroom, but not in the kitchen ever, especially when food is present."
Also, remind her that bird poop can spread diseases and bacteria and needs to be cleaned and sanitized with more than just water, and very regularly, as fungus can grow in dried poop and spread illness.
Bird poop isn't just poop, it is a mixture of poop, urine and urates... eww.
Do you have a rental contract you can show her about pets? Pet feces, no matter the type of animal shouldn't just be laying around the house and in the kitchen, that is so unsanitary, for any amount of time. There are more than 60 types of diseases people can get from bird droppings by the way, maybe she needs a reality check:
http://www.medicalnewstoday.com/releases/61646.php
Even if the birds are not carriers of any of the above diseases, the poop and floating feathers can still carry bacteria and other disgusting things that can make you sick.
If she doesn't take the hint, then you can go find some dog poop in a yard and put in on her pillow. Then say, "Oh! I just had a cute puppy over for a while." Then, put it in the trash and spray her pillow with water to 'clean' it up right in front of her.