The first waterfowl arrive at Arapaho when the ice vanishes in April, while peak migration occurs in late May when 5,000 or more ducks may be present. Canada geese have been reestablished in North Park and begin nesting on the refuge during April. Duck nesting usually starts in early June and peaks in late June. The refuge produces about 9,000 ducklings and 150 to 200 goslings each year.

Primary upland nesting species include the mallard, pintail, gadwall, and American widgeon. A number of diving ducks, including the lesser scaup and redhead, nest on the larger ponds and adjacent wet meadows. Most species may be observed during the entire summer season. Fall migration reaches its height in late September or early October when up to 8,000 waterfowl may be on the refuge.

Refuge wetlands also attract numerous marsh, shore, and water birds. Sora and Virginia rails are numerous but seldom seen. Wilson's phalarope, American avocet, willet, sandpipers, yellowlegs, and dowitchers are easy to observe, when present. Other less common species include great blue heron, black-crowned night heron, American bittern, and eared and pied-billed grebe.

• Birders should visit the upland hills in the winter to see the large (over 200) population of sage grouse.
• Nature Photographers should take advantage of the vibrant sense of life here: faint whirring of insects, murmur of moving water, comings and goings of mammals, and the flights of birds set against the brilliant sky at dawn or dusk.
• Take the self-guided 6-mile auto tour and learn about the habitat of the refuge and its wildlife.