Yesterday, I saw a group of about 25 northern shovelers swimming in a tight circle on the pond in the CU research park by the bike path SW of Foothills and Arapahoe. They herd and eat insects and snails that they stir up with their feet in the mud. Also, ringneck ducks were doing their mating displays, ducking under, leaping up, splashing, with their wings.   http://nwbackyardbirder.blogspot.com/2010/11/feeding-habits-of-northern-shoveler.html