I'm sure it was a test of the technology on a species smaller than humans, but I don't know the answer to why sparrows specifically. I still haven't been face to face with whoever was behind it to ask.

[And he would really love to ask. He can understand why an invertebrate might be too far away from human physiology to be a good test, but why not a small mammal or even a more directly related primate?

While he continues his story, their drinks arrive, but he ignores his.]

When the test on sparrows was successful, they turned to us. I still remember the green light spreading to cover everything.