It's easier to start your seeds indoors, under CFL's and then move them outdoors once the weather is better and the plants have at least a few nodes.

As far as keeping pests away....

You'll never keep bugs away unless you use a pesticide of some sort, but that can kill your plant if you don't use caution.
Birds would be kept away by the soda can, they probably won't wanna reach over it. You could put a screen over it to be safe.

Good luck.