For sure birds *are* solar powered, where do you think the energy for making plants, other animals, and for moving air is coming from?
The point with clean energy is that the time interval between the arrival of solar energy on earth and the moment we use it, it transforms into heat and is finally released into space as infrared radiation should be short with respect to the longest time-scale of our ecosystem, so as to not disturb it too much. In this way the carbon released into the atmosphere remains bounded.
Jet planes use oil which normally does not participate to the ecosystem. Oil needed 100's of millions years to accumulate, if not more, and releasing this carbon in a couple of centuries is not the smartest idea. The solar or not origin of oil is irrelevant.