;)
This painting is about the circle of life, but mostly about the impending doom of death represented by a sky full of heavy, dark clouds, a large human skull and vultures (buitres), circling above. A fireball represents a meteor that has theoretically killed off species before, i.e. the dinosaurs.
The title comes from a poem 'Rubaiyat of Omar Khayyam' (translated by Edward Fitzgerald), the last line, the bird is on the wing (a very familiar phrase), means that we all face mortality. In the next to last line, the bird of time has but a little way, the bird is a metaphor for time itself. In the painting a vulture is used as the specific bird, more in line with death. The flowers offer the hope of rebirth.