Yes, it is okay to keep a single pet bird as long as the bird receives proper care, attention, and social interaction from its owner. Some bird species can thrive and bond well with their human companions even when kept as solo pets. It's important to provide mental stimulation, a balanced diet, and a safe and comfortable living environment for a single pet bird. Additionally, spending quality time with your pet bird through daily interaction and play can help ensure its well-being and happiness.