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BUTTERFLY ASSEMBLAGES ALONG THE LOWER COLORADO RIVER <br />7 <br />~-- a I Standard error March a j <br />6 <br />5 ~ 'Mean ~ <br />4 a,c <br />3 ~ b,c <br />2 b b <br />1 ~i b T <br />0 <br />.~, ~ <br />r <br />X 6 a June <br />... 5 <br />~ 4 a b a,b <br />~' T <br />` 3 ~ a,b 1 <br />~ 2 a,b <br />1 b <br />a,b <br />0 <br />O ~ <br />N <br />y 6 August <br />p 5 a <br />~ 4 ~ ~ a.b,c <br />` 3 <br />~ 2 ~ .L <br />~ 1 a,b,c ~ o <br />c <br />-~~ ~ <br />7 <br />6 <br />5 <br />4 <br />3 <br />2 <br />1 <br />0 <br />497 <br />0,~ <br />Sites <br />Figure 6. Nectar resources by season at Colorado River sites. Station codes indicate the year planted. Stations with different letters <br />indicates a statistically significant difference (p < 0.05) between stations for the given month <br />Although no revegetated site supported a butterfly assemblage similar to that of the BW reference site, <br />several butterfly species occurred at both revegetated and BW sites. Larvae of these species feed on <br />mesquite (L. marina, H. ceraunus, A. palmeri) (Comstock and Dammers, 1932; Emmel and Emmel, 1973; <br />Scott, 1986), saltbush, or quailbrush (Brephidium exile and H. gracielae) (Emmel and Emmel, 1973). <br />Because these plants were historically associated with the Second Bottom, these butterflies were probably <br />also associated with that portion of the floodplain. Butterflies associated with agriculture (e.g., Colias <br />eurytheme) were also found at all sites. Colias eurytheme has probably become more common as a result <br />of river regulation and the associated conversion of riparian forest to agriculture (Stern and Smith, 1960). <br />Butterflies present most years at BW and absent from other sites included Limenitis archippus, <br />Calephelis nemesis, and Junonia coenia. The first two of these are associated with First Bottom trees <br />or shrubs whereas J. coenia feeds on herbaceous vegetation. Nymphalis antiopa, a First Bottom <br />Copyright ©1999 John Wiley & Sons, Ltd. Regal. Riuers: Res. Mgml. 15: 485-504 (1999) <br />