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and yellowthroat. Of these species, only the yellowthroat was observed in <br /> sufficient n=bers to exhibit an affinity for the type. <br /> Upland sagebrush. The sagebrush vegetation type supported a total of eight <br /> passerine species during the June, 1979 census. The violet-green swallow <br /> and red-winced blackbird were the most abundant species observed. The <br /> sagebrush :-lal_,itat supported the lowest total avian population of all types <br /> sar-pled (22.7 individuals/'ar). The Shannon-Weiner species diver- <br /> sity index: (1.52) was relatively high because the number of observations was <br /> ecually Cistributed among species. Bullock's oriole and the barn swallow <br /> were observed only in the sagebrush; however, neither were observed in <br /> sufficient ntn^bers to indicate an affinity for this habitat. <br /> Grassland pasture. The grassland pasture vegetation type was the most homo- <br /> geneous vegetation type sampled and accordingly, the least diverse in terms <br /> of nim be._-s of bird species observed (4) . The western meadowlark represented <br /> at least 75% of all sightings during the June, 1979 census. Due to the low <br /> number c,f species observed and the dominance by the western meadowlark, the <br /> Shannon-Weiner species diversity index in this type was lowest (0.69) of <br /> all types sampled. The total av-an population supported by this habitat <br /> was 26.0 individuals/krp, the lowest of all species sampled after upland <br /> sagebrush (22.7 individuals/Qn) . <br /> in-)ortant breeding passerine birds. Twenty-two different avian species <br /> were er:oauntered along the breeding bird transects conducted in the five <br /> vegetation types surveyed. Abundant passerine species in decreasing order <br /> of relative abundance during June, 1979 census were: red-winged blackbird, <br /> violet-green swallow, cc.rrmn crow, and western meadowlark. All of these <br /> species except western meadowlark were observed in at least four of the five <br /> vegetation types sampled. <br /> Red-winged blackbird. The red-winced blackbird was the most abundant species <br /> observed on the study area averaging 19.5 invididuals/}an over all habitats. <br /> This ubiquitous species was encountered on all five vegetation types and was <br /> the rx�st abundant species in each type. The red-winged blackbird is crre- <br /> carious and feeds, flys and roosts in flocks. It was most abundant in ripar- <br /> ian and alfalfa field habitats and showed an affinity for these types. <br /> -33- <br /> J U N 1 1 1980 <br />