Penguin should help with breeding more, help prevent babies from getting too cold or too hot, seeing as we have no way to cool things down easily.
Rabbits should do.... something... other than breed fast. Maybe increase jump height slightly.
Would help if pigs could be used to dig in the ground similar to a shovel, because I need more worms to tame my crows. On that note, digging should be applicable to the 2x events....
Crows should be able to attack on command, you can command them to attack currently, but they dont actually attack. Unless I am doing something wrong.