The mosaic of different habitats on the refuge provides for abundant wildlife throughout the year. At least 250 species of birds have been recorded and viewing is always an exceptional experience. The greatest diversity of bird species occurs during the spring and fall migrations. Shorebirds and passerines are both in greatest abundance at these times. Winter is marked by the greatest abundance of many waterfowl species. Cackling geese, green-winged teal, and American wigeon are present in extremely large numbers. The freshwater wetlands are managed in a way that maximizes sustenance and habitat for these species during winter months. Summer months seem quiet but upon closer observation, visitors can see nesting birds, including hummingbird nests.