The lognormal species curves obtained using pooled data for the five 

 routes are shown in figure 23. In 1978, 94 breeding species were regis- 

 tered on May-July runs of the routes, while the species-abundance relation 

 predicts 101.7 species in the theoretical universe bounded by the curve. 

 Sampling, therefore, appears to be about 92/o complete. When all May-July 

 data for the period 1977-1979 are pooled, the number of breeding species 

 actually encountered rises to 101, while the theoretical number of soecies 

 if 104.4. Sampling in this case appears to be 97% complete. As shown in 

 the figure, the curve advances to the right as sample size increases, yet 

 retains its shape. The roadside survey is, therefore, 92% or more effective 

 in sampling the bird community present in the area defined by the sample 

 radius. For individual routes, sampling completeness based on cumulative 

 1977-1979 data is somewhat more variable, ranging from 75% to 97%. 



The shape of the species curve provides an accurate and precise 

 "fingerprint" of the bird communi ty--and hence of environmental conditions-- 

 sampled by the roadside survey. Curves for different routes are shaped 

 differently and distinctively (figure 24), while curves for individual 

 routes are remarkably constant in shape from year to year (figure 25). 



The shape of the various species curves is closely related to the 

 species variety and equitability parameters as revealed by the factor 

 analysis discussed above. In general, a more diverse community will show: 

 (1) a taller species curve, reflecting a larger valve of Sg and greater 

 species variety; (2) a narrower species curve, reflecting greater equit- 

 ability; and (3) a species curve encompassing a larger area. Examination 

 of figure 24 allows quick visual comparison of various ecological features 

 of the five routes. It is evident from this figure that the floodplain 

 habitats sampled by the Missouri River route have a high species variety 

 and high equitability, as the species curve is relatively tall and steep. 

 The badlands community sampled by the Flowing Well route has much lower 

 values for these parameters, and hence a low, shallow species curve. The 

 Circle route also has low species variety and equitability, but its species 

 curve encompasses a relatively large area. The lognormal curves, therefore, 

 provide an ideal monitoring tool: they are sensitive to community attri- 

 butes, allow easy visual comparison of samples, and provide a precise 

 measurement of the community which, if undisturbed, varies little from 

 year to year. 



These data lend support to the use of breeding bird community structure 

 as a sensitive environmental indicator. We would expect bird community 

 structure to be indirectly but measurably affected by any major change in 

 (1) habitat quality or extent; (2) habitat vertical structure and patchiness; 

 (3) prey availability (seeds, insects, rodents, other birds, etc.); (4) 

 densities of competitors and predators, and (5) intensity of disturbances 

 such as noise, dust, traffic, and increased hunting pressure. The syn- 

 ergistic effects of several such changes occurring together should have an 

 especially marked influence. Therefore, while the three years' pre-project 

 data reported here show community structure in the study area to be remark- 

 ably constant from year to year, a statistically significant change in the 

 relative positions of experimental and control communities would provide 

 strong evidence for a biologically significant change. In the words of 

 Sharma et al. (1975), "...if an impact is measurable, then a change detected 

 by our crude schemes must be very large and consequently significant." Con- 

 current monitoring of single species abundances as well as several community 

 attributes (diversity, evenness, trophic composition, etc.) would provide 



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