Thank you for the feedback.
As for the theme, we kind of broke it down to:
Time: the farmer is running against time. He has to kill the invading birds before they destroy all his crops
Speed: the birds move very fast (when you think you've got them, they fly away)
Multiplying: there are lots of birds and once you kill a certain number, they'll respawn again
Towards: the birds moving towards the crops to destroy them.
Basically, this is how we interpreted the theme :)