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• arunLL:ance in one or riore habitat type or t:,ose wits, a wr-ce distributicr. <br />(i.e., found in most habitat types sa;npled). <br />Passerine Breed_inc, Habitats <br />Juniper. .~~re avian species were observed in the juniper vegetation type <br />than in any other type surveyed during the breeding passerine surveys <br />(12 species). Accoraingly, this type had the higY.est scecies diversity <br />index of any type surveyed in t`ie study area (1.91). %:e structural heter- <br />ogeneity of tine juniper type with its tree strata:. provide rare opportun- <br />ities for nesting and feeding "niches'' than other vegetation types in the <br />area; as a result, the type can support a greater variety of bird species <br />and a high population of~birds. This 7labitat supported the second highest <br />avian population (40.0 individuals/]c~). The cost abundant species observed <br />in this habitat in decreasing order o: relative abundace wexe: red-~~~inged <br />blackbird. violet-green swallow, western meadowlark, and A;resican robin. <br />Three passerine species that were encountered in the juniper vegetation <br />hype but not observed else4lnere during t'~e June, 1979 census were ash- <br />• throated flycatcher, blue grosbeak and Cassia's finch. The western meadow- <br />lark arri rVmsic<in robin exhibited an affinity for tre juniper vegetation. <br />Alfalfa field. A total of nine passerine species was encountered in tY'.e <br />alfalfa field. The most abundant species observed in decreasing order <br />of relative abundance were: red-winged blackbird, violet-gree.-~ swallow, <br />and cliff swallaa. This habitat supported the highest total avian popu- <br />lation (55.3 inoividuals/an),and the third highest species diversity index <br />(1.25). The western flycatcher and black-billed ragpie were observed <br />only in the alfalfa field during the breeding bird census. Ha.~ever, only <br />the violet green swallow exhibited a definite affinity for the alfalfa field. <br />Riparian. The riparian vegetation type supported a total of nine avian <br />species. The Shannon-Weiner species diversity index ir. this habitat w4s <br />the secon8 lowest of all types sa-npled (1.2i) and the total avian popu- <br />• lation was 36.0 individuals/}an. The red-winged blackbird was the most <br />. aburcllnt species encountered along the riparian. transect. :^nree passerine <br />species observed in this vegetation type and not observed elsew~.cre ~.:::+'.c, <br />thr~ June, 1579 mnFUS were lone-pilled rarsh wren, ora-.ce-c"c~.':PC: w~r:~:e„ I <br />-32- <br />JUNSSt980. <br />