The Main Ring Moat is a series of connected ponds that forms a circle just inside the Tevatron accelerator ring. The ponds are used as a source of cooling water for the accelerator components which means that they often remain open even when most of the lake on site are frozen and that means that the moat is a good place to look for wintering waterfowl. Main Ring road runs in a circle between the moat and the accelerator ring and hence allows one to get close up looks at both wintering and migrating waterfowl. It also provides good views of the prairie inside the ring where, in winter, one can often find Northern Shrikes and Rough-legged Hawks as well as Snow Buntings along the road itself. In 1999 a male Ring-necked Duck spent an entire summer on the north-western part of the moat and more recently a Pied-billed Grebe has spent the entire winter on the south-eastern part.