He flies through a clothing line, ends up with a dress over his face, and smacks into a landing jet plane. Seems like a Stephen Neary film to me. I think I was reading too much Dostoyevsky at the time. These birds appeared again in a little film called "The Rocket". Here are two of them falling in love from a "Rocket" pencil test.
At this point, the birds were very warm, sympathetic characters. When they first appeared in The Parkbench, that was still the case... but they were BORING! I realized they had to be a little less sympathetic, a little less intelligent, because one of them was going to die and it had to be funny. Well, it turns out the easiest way to make a bird look dumber is to move his eyeballs out to the side (less human, more birdlike). Oh, and add a big flat head shaped like a hockey puck.
Here is a pencil test of one of these birds standing up after his crash landing. This was one of the first things I animated after redesigning the film and it really helped set the tone for the whole project.