A 6-year-old female red lory (Eos bornea) was presented with abdominal swelling and nesting behavior, which could be suggestive of hyperestrogenism. On physical examination, the bird was obese and had a firm palpable mass extending from the keel to the pubic bones. Elevated biochemical analytes included alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, creatine kinase, and cholesterol. A ventral midline abdominal hernia, severe hepatomegaly, and polyostotic hyperostosis were diagnosed on the basis of whole body radiographs and abdominal ultrasound. The abdominal hernia was reduced successfully through a ventral midline celiotomy. Severe and diffuse hepatic lipidosis with mild biliary hyperplasia was observed histologically from a liver biopsy. Postoperative management consisting of diet modification and increased exercise resulted in a significant decrease in liver size radiographically 6 months after surgery.