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to a n.4.. CO.. ur, e.r. r? ForA G3? ?GAANfl LANPL ?' CN`r 1\0?A ffNe . T IV. Y - D V, DAM ?:,' D! L T A D O V N DANS ?. 1 J M O N T n 0! C O o U N T T N EAST CANAL -To D DIV A° A, ''IRONSTONE OIV. DAN QV ,_10UTZlNNIZlR ( p1yNDAM CANAL ? S' jD V LDAM' ?j/?j/ S GedOT ? t jj//\ GJN ,NNE + „... Grnr COLOR4D0 WEST MONTROSE r/r CANAL-- /%/ ,% / %j?j/•? b •LDUTZ[NNIZER It Ti'„ ? ( j ? ?OI V. DAN -SOUTH CANAL 1 Ollnni SCALE Of MILES I O S T' .. D IV. DAM?LTA SCALE OF KILOMETERS u° ®IRRIGATEO AREA Figure 1. -Location and study area maps, Lower Gunnison River Basin, Colorado Phase II was an intensive study on 30 selected wetland sites to sample plant, bird and small mammal populations. Wetlands were ranked according to use by plants, birds and mammals. Wetland use values were based on a summation of ratings for six parameters: small mammal numbers and diversity, large mammal observations, breeding bird density and diversity, and native plant condition. The 30 selected sites were arbitrarily chosen to represent the four dominant FWS wetland types (forest, scrub/shrub, emergent- narrow-leaved and emergent/interspersed with water); principal water sources (natural, canal and irrigation management); and three general locations (east side of the Uncompah- gre River, west side and riverbottom). Bird censuses were after Emlen (19711 1977) as modified by Franzreb (1977). Small mammals were trapped following a technique described by Calhoun (1948). Wildlife use values were compared to wildlife habitat values as adapted from Golet (1973, 1973a). During Phase II a monitoring system was established which included installation of an engraved steel post bearing the wetland identification number and making a photogra- phic record of each sample wetland. Vegeta- tion maps were prepared for each sample wetlaInd as part of the monitoring system. RESULTS Phase I - Extensive Assessment Approximately 8,773 ha of wetland habitat were found in the 72,000-ha study area where wetlands ranged in size from 0.1 to 345 ha and averaged 11 ha. Wildlife habitat values for 804 wetlands ranged from 41 to 119 and averaged 78 on a scale of 41 to 123. Dominant FWS wetland types were: forest (40X), emergent/narrow-leaved (27X), scrub/shrub (9%) and emergent/interspersed with water (4%). Natural water sources were wholly or partially responsible for 80 per- cent of the wetland habitat, irrigation management to 37 percent and canals to 5.5 percent. Table 1 is a summary of the inventory data from Phase I. Natural wetlands were found primarily along rivers and their tributaries and drain- ages. The presence of wetlands supported by canals and irrigation management appeared to be determined largely by the terrain and on- 312