How about different options for the starting bird:
Goose - Well Rounded...
Swan - More points, but slower (as in the game)
Duck - More durable
Arctic Tern - Faster (best navigator)
?Flamingo - Tons of points, terrible flier
*Penguins - For fun, who doesnt love penguins?!
Here's an option for something to add:
Say if 10 birds hit an airplane it gets struck down. And the rate can increase on larger planes and decrease on smaller ones.