Oregon's Willamette Valley was once a rich mix of wildlife habitats. Valley wetlands were once extensive, with meandering stream channels and vast seasonal marshes. Today, the valley is a mix of farmland and growing cities, with few areas remaining for wildlife. The 2,492 acre Baskett Slough National Wildlife Refuge was created to provide vital wintering habitat for dusky Canada geese. Unlike most other Canada geese, duskies have limited summer and winter ranges. They nest on Alaska's Copper River Delta and winter almost exclusively in the Willamette Valley. Habitat loss, predation, and hunting caused a decrease in their population. Dusky Canada Geese usually appear here first in the fall and use the refuge as their last stop before starting the spring journey back to their Alaska nesting grounds. The refuge's farmed fields, rolling oak-covered hills, grass fields, and shallow wetlands are home to many wildlife species. A small number of Bald Eagles winter on the refuge. In addition to the abundant bird life, 30 species of mammals, 8 species of amphibians, and 10 species of reptiles occur here. The largest remaining population of Fender's blue butterfly is found on the refuge.