Breeding Bird Census 



Table 15 summarizes 1977 and 1978 results for the five breeding 

 bird census plots. A more complete account of 1978 results is given 

 in Appendix C, and plot descriptions can be found in Appendix F of 

 the WBS. 



The spectacular increase in grass production in 1978 was reflected 

 by changes in breeding bird densities on the grassland plots. Lark 

 buntings established breeding territories on the grassland plots for the 

 first time in 1978, and chestnut-collared longspur densities increased 

 markedly above 1977 densities. Total number of territories, total 

 density, and total biomass showed a sizable increase on both grassland 

 plots in 1978, while single and two-species dominance decreased. 



Total species number and species diversity remained unchanged 

 for the five plots combined, and species and cummunity parameters for 

 the shrub-dominated plots were similar both years. 



Roadside Wildlife Survey 



Data obtained during the fifteen 1978 roadside survey runs are 

 presented in Appendix D. The cumulative numbers of species for all May- 

 July runs (1977-1978) are presented in Table 16. Species number, richness, 

 and species diversity showed a general increase in 1978, probably related 

 to moister conditions and increased diversity of water birds. (The number 

 of species and individuals of anatidae and other large water birds showed 

 a marked increase in 1978). The relative sequence of routes with respect 

 to community parameters was similar to that observed in 1977, with the 

 exception of the Circle route, which showed a disproportionately large 

 increase in diversity. 



Table 17 summarizes 1977-78 changes in May-July sample abundances 

 of selected species, based on data obtained during runs of the five road- 

 side survey routes. The ring-necked pheasant, mourning dove, and black- 

 billed magpie showed highly significant decreases in sample abundances 

 from 1977 to 1978 (p <'.0l), while Baird's sparrow and chestnut-collared 

 longspur showed significant increases (.01 <p <.05). The apparent 

 increase in Baird's sparrow is believed to be an artifact of increased 

 observer familiarity with songs of that species. 



Figure 9 shows a two-dimensional ordination of 1977 and 1978 species 

 abundances for selected species sampled by the roadside routes. The 

 first two factors together accounted for 20.3 percent of the observed 

 variation in sample abundances. Factor I separates species according to 

 foliage height diversity, with species preferring grassy or badlands 



44 



