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I. !~ili,~:u " i I o , I J ~ 'I U Ul I J . . ~. ^., , U lJ 1.1.. ,V' . , The National Wetland Inventory (FWS 1979) revealed 43,122 acres of wetlands in the Closed Bas~n project area. As shown in Table 1, the project area produces approximately 13,620 ducks annually at a density of .31 ducks/wetland acre. Without the project there would be about 2,200 man-days of waterfowl hunting and 1,000 man-days of wildlife oriented recreation. A resident population of Canada geese breed in the San Luis Valley. Approxi- mately 100 of those utilize the Closed Basin project area for nesting and produce 160 young (80 percent success, 4 yg./brood annually. The population of Canada geese is increasing in the San Luis Valley. (2) Other Water Bird Use - Other water bird data is very limited for the project area. The Bureau of Reclamation conducted aerial surveys within the area to determine the general seasonal use by wetland type. However, the collected data is not sufficient to extrapolate production estimates. Use-day information for Alamosa and Monte Vista NWR may be more appropriate in determining other water bird use of the project area. In general, the species have been classed into three types: Raptors, shorebirds, and marsh and water birds. Use by these species in the San Luis Valley varies with each individual species. Some of the species such as American avocets, Wilson's phalarope, killdeer, common snipe, rails, black-crowned night herons, snowy egret, marsh hawk, Swainson's hawk and short~eared and great horned owls breed in the Valley. The majority of the other species are either fall and spring migrants or winter visitors. Most of the breeding species either leave during winter months or remain in reduced numbers. The quality and quantity of the wetlands in the San Luis Valley probably have the greatest effect on the species ~hat breed there. Wetland vigor and abund- ance will determine how many of the species can find nesting places, and how many young they can produce. For migratory species and winter visitors, wetland health plays an important role, but not as critical as for the breeding species. Numbers of migrants are affected by the availability of suitable breeding habitat, storms during migration periods, winter weather and the available winter habitat. The following lists of raptors, shorebirds, and marsh and waterbirds in Tables 2. 3 and 4 respectively, were recorded from the Alamosa and Monte Vista NWR in 1979 and 1980. The Tables do not represent a complete species list for wetlands in the San Luis Valley. Species shown in the Tables are the most conspicuous species and hence the most frequently seen. 9-