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Wildlife Relationships In these pools are "a soup" of invertebrates, both insect larvae and adult fairy shrimp (Branchinecta sp.),copepods, water fleas (Daphnia sp) and others. As temperatures rise and pools begin receding, insects begin to reproduce. The red larvae of Chironomid midges are most evident as are predaceous diving beetles, aquatic Hemipterans (true bugs), and other Dipterans (flies and mosquitoes). Most pools on the ranch are too small to support larger,predaceous insects such as dragonflies. The invertebrate "soup" is what makes these seasonal marsh systems so attractive to waterfowl, shorebirds, and other species adapted to procuring the rich food source. Migrant dunlin, least sandpipers (C. minutilla), greater yellowlegs, black-necked stilt (Himantopus mexicanus), and common snipe are dependent upon these communities for late winter and spring. Waterfowl such as wood duck (Aix sponsa), green-winged (Anas crecca) and cinnamon teal (A. cyanoptera), mallard (A.platyrhynchos) and American wigeon (A. americana) also forage on invertebrates and vegetation in these pools. Waterfowl. An in-depth discussion of waterfowl is presented at this time since waterfowl dominate the winter scene on the ranch's wetlands. Buckeye Ranch supports 17 species of waterfowl that can be divided into three groups: wintering species, spring-fall migrants and breeding species (Appendix B). The California Delta is a waterfowl wintering area of national and international significance, generally supporting about 10% of California's wintering waterfowl (USFWS 1991). The Cosumnes River Preserve regularly winters 10 - 20,000 ducks, 1,000 swans, and 2 - 5,000 geese (Ducks Unlimited waterfowl surveys). Waterfowl use patterns are poorly understood in the North Delta, but surveys on the Cosumnes Preserve Buckeye Ranch Resource Plan (November, 1993) 54