The post on the bottom will be part of the shoulder of the bird's body. I will keep adding more wax and build up the body slowly. But that is how you'd add a sprue. Though with a sprue you want to use a pin tool, heat it up and effectively poke it deep between each edge where it joins the main piece to ensure the wax has melted together all the way to the center of the rod. You need a good bond with sprues to ensure they don't break off when coating your piece, when building a sculpture it is less important since there is more wax involved and the wax isn't really supporting a lot of weight.
Glad you found it helpful Addison, now let's see your creations!
Also, I've found that square rod used for sprues seems to crack more than round sprues. Not sure why this is. A bronze foundry once told me that square spruing is better for bronze because it reduces the spiraling turbulence you get with round rod. Given that I am not sure what they are doing to keep their molds together better than mine but there it is. Perhaps I'll make the main pouring sprue round and the little bottom feeders that directly touch the part square. Square feeders do seem to give a better finished piece with fewer defects.