I painted my birds nails once. I had no problems the birds did not even notice. Anyway I did it because one of our chicken went broody and was hiding in the yard. I have another chicken that looked just like her so I painted the other chicken's nails so I could tell them apart and catch her when she returned. Then I tied a piece of yarn to the broody chicken to find the hidden nest when she returned to it. She actually didn't even care and my stupid plan worked. lol