During the winter my pond stayed topped up and full. As soon as spring hit it dropped at least a foot maybe more.

Is that because of vegetation around the pond? It seems like it's staying at it's current level pretty well (with well water flowing to it), it's just strange how abrupt I lost water.

I'm assuming because all the trees woke up they just took a big sip out of it to get their juices flowing?

The small tree lined creeks around here cease to flow except after a substantial rain as soon as the trees leaf out in spring. I think the trees take out a lot of water. When the trees drop their leaves in fall, even without much rainfall, the creek beds slowly fill up again and begin flowing a little.