There should be some type of bird that can hold its breath and is light enough to temporarily go into space. Kind of like flying fish, but birds jumping into space, orbiting for a bit, and then dropping down back into the atmosphere.
Maybe the oldest birds care for the eggs, and on their last life they launch straight into space, where they travel until they reach another planet (which could be days, years, or millennia later) at which point the eggs hatch.
So when you are traveling in space, you might find an old bird, protecting the next generation even through death, and then you can bring it to your planet and start a new population of these birds.