Answer:
Thank you for your question. I forwarded it on to our in-house veterinary staff, and this is a response from Dr. Holly Nash:
Peanut butter is relatively high in fat, and would generally not be recommended as a component of a lovebird diet. Just like many of us, our pet birds just don’t need those added calories, which cause the birds to not eat what they should and gain excess weight. In addition to a pelleted diet, I would rather the bird receive a variety of fresh veggies and a small amount of fruit as a treat. - Holly