Laserfiche WebLink
abundance in one or more habitat type or those with a wide distr.ilexe cn <br />(i.e., foend in most habitat types sampled) . <br />Passerine Breeding Habitats <br />eun per. .'rare avian species were observed in the juniper vegetation type <br />than in any other type surveyed during the breeding passerine surveys <br />(12 species) . Accordingly, this type had the highest species diversity <br />index of any type surveyed in the study area (1.91) . The structural heter- <br />ogeneity of the juniper type with its tree straten provide more opporu:n- <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 habitat supported the second highest <br />avian population (40.0 individeel s/.c;i) . The .:east abundant species observed <br />in this habitat in decreasing order of relative abundance were: red -- winged <br />blackbird, violet -green swallow, western meadowlark, and American robin. <br />Three passerine species that were encountered in the juniper vegetation <br />type but not observed elsewhere during the June, 1979 census were ash - <br />throatea flycatcher, blue eeosbeak and Cassin's finch. The western meadow - <br />lark and American robin e hthitee an affinity for the juniper vegetation. <br />Alfalfa field. A total of 'nine passerine species was encountered in the <br />alfalfa field. The most abundant species observed in decreasing order <br />of relative abundance were: red - winged blackbird, violet -green swallow, <br />and cliff swallow. This habitat supported the highest total avian popu- <br />lation (45.3 individuals/km),and the third highest species diversity index <br />(1.25). The western flycatcher and black - billed magpie were observed <br />only in the alfalfa field during the breeding bird census. However, 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 in this habitat was <br />the second lowest of all types sampled (1.21) and the total avian popu- <br />lation was 36.0 individuals/km. The red - winged blackbird was the most <br />abundant species encountered along the riparian transect. Three passerine <br />L species observed in this vegetation type and not observed elsewhere during <br />thr' June, 1979 census were lone - billed marsh wren, orange -crowned enr, eer, <br />-32- <br />JUN 1114$O, <br />