The Avon Hills represent the largest, relatively intact block of kettle and moraine forested landscape remnant remaining between the Twin Cities and Morrison County (Camp Ripley IBA). Historically, Collegeville Township was the site of the only known Stearns County nest of the Passenger Pigeon in 1881 and the second to last breeding record of the Swallow-tailed Kite in 1904 in the entire Midwest. In recent decades this area has been an important first foothold in central Minnesota for northward-moving species such as Red-shouldered Hawk, Blue-gray Gnatcatcher, Northern Cardinal, Wood Thrush and Red-bellied Woodpecker, all of which are now well-established.
Scattered recent records of Blue-winged Warbler and Prairie Warbler hint at possible breeding and future establishment of these species. The Red-shouldered Hawk population is widespread within this Important Bird Area, occurring in all four townships and is as common here as any place in the state with the possible exception of Camp Ripley IBA. Other southern birds that have occurred here, but which have not yet established a breeding foothold include the Yellow-crowned Night Heron, Prothonotary Warbler, Louisiana Water-thrush, and Hooded Warbler.
The area has a very high breeding Wood Duck population due perhaps to the forested kettle landscape. Fall concentrations have totaled 400 birds on just one remote Collegeville Township bog. Several waterfowl production areas in southern Collegeville Township produce many pairs of Mallard, Blue-winged Teal, Wood Duck, Hooded Merganser, Pied-billed Grebe, and a few Red-necked Grebes.