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in the birds. In conclusion, it is believed that removal of nonnative fish species from floodplain ponds along the Upper Colorado and Gunnison rivers would not cause a significant adverse impact on fish-eating birds because alternate feeding areas are available adjacent to the floodplains where ponds would be reclaimed. Removal of nonnative fish species from some floodplain ponds along the Upper Colorado and Gunnison rivers will not result in complete e 1 i mi nat i on of small fi sh that serve as food for bi rds . Although there would'be a minor negative impact to piscivorous bird species, this would be offset wi th a pos it i ve impact of increased aquat i c invertebrates for shorebirds and waterfowl. Endanqered Species. Food supplies for young life stages of the endangered fi shes, duri ng the crit i ca 1 peri od when hi gh mortal i ty can occur, are limited in the main channels of rivers in the Upper Colorado River Basin (Wydoski and Wick 1996). Zoop1 ankton used for' food by newly hatched endangered fishes are more abundant in backwaters and embaymentsconnected to the river and most abundant in flooded bottomland habitats (Cooper and Severn 1994a,b,c,d; Mabey and Schiozawa 1993). However, nonnative fish species in such habitats prey on and compete with the young life stages of the endangered fishes. . Osmundson (1986) found that endangered fishes in riverside ponds along the Colorado River survived and grew well in 'ponds free of nonnati"ve fishes. Reclamation of floodplain ponds would remove the potential of predation and competition by nonnative fish species that occurs to young endangered fishes in the backwaters and embayments of the rivers. Reclaimed floodplain ponds would be excellent grow-out facil ities for captive-reared endangered fishes prior to release into the rivers of the Upper Colorado River Basin (Osmundson and Kaeding 1989). Surveys of floodplain ponds in the Upper Colorado River for Colorado squawfish and razorback suckers in the late 1980's were negative. Only one private pond near DeBeque, Colorado contained razorback suckers that were the offspring of several razorbacks that were stranded after the 100-year floods of 1983 or 1984 receded. However, surveys will be conducted prior to chemical treatment to check for endangered fishes with gears such as e1ectrofishing, trammel nets, and trap nets. Although there is a possibility that an endangered fish in a floodplain pond could be killed by the chemical treatment, it is not anticipated that many (perhaps one or two) endangered fish would be killed through the proposed action. The benefits to endangered fi sh recovery are bel i eved to be greater than the remote poss i bi 1 i ty of ki 11 i ng one or several endangered fi sh duri ng chemi ca 1 treatment. Powdered rotenone to be used in chemical treatment of floodplain ponds would be applied carefully so that drift of the powder is controlled and confined to the target area. Since rotenone is toxic to terrestrial insects that are used as food by endangered species such as the Southwestern willow flycatcher, extra precautions will be taken to prevent treatment of nontarget areas. 20