Hesitation? A cage is familiarity; the sky is opportunity. A cage is all the known safeties; the sky is risk-taking and chance and the life it was born to live. But let the hesitation be. Let the bird get the measure of itself as it gets the measure of the sky.
Just open the door? Let the new beginning be taken at its own pace. That swallow just now, fluttering against a window (and possibly trapped there for much of the morning). Pausing for a moment on my hand, just a moment, before regaining the sky.
When you're done, leave the cage open. Do this by removing the door altogether.