thought of as the breeding species pool for this area, and the total cumulative 

 number of species recorded on McCone County routes during monitoring should 

 approach this figure over time. In this study, 105 breeding species or summer 

 visitors were recorded during 1977. The cumulative species number for this 

 stratum, however, is higher than the continental average of 115.5, indicating a 

 relatively diverse bird species pool. 



June species diversity for the five routes ranged from 2.218 on the Flowing 

 Well route to 2.945 on the Prairie Elk route. The average for the five routes 

 was 2.630. This is higher than either the 1973 average for the 33 routes in the 

 stratum (2.530) or the 6-year averages for the stratum (2.383). It is, however, 

 lower than the six-year continental average of 2.950. Species diversity for the 

 five June runs combined is 2.902, which is virtually identical to the figure of 

 2.901 reported for the pooled 1968-1973 runs of all routes in the stratum. It is 

 considerably lower, however, than both the value of 3.02 for pooled 1973 runs 

 within the stratum, and the value of 3.456 for pooled 1968-1973 continental data. 



The five routes differed considerably in species composition of the two 

 dominant species and seasonal differences in dominance were also evident. The 

 horned lark was the dominant or second dominant species in 30 of the 44 standard 

 route runs, and was first in rank for 23 runs. However, this dominance was prim- 

 arily during non-breeding months; it was dominant or second dominant in only 

 7 of the 15 breeding season runs, including the Dreyer Ranch route. The western 

 meadowlark, which was dominant in ten yearlong and second dominant in 11 of the 

 44 runs, was dominant or second dominant in 13 of these 15 breeding season runs. 

 For the four standard routes combined, the horned lark was dominant only during 

 September through March; dominance was assumed by the western meadowlark or, 

 in July, by the mourning dove during remaining months. 



The horned lark was dominant in all 11 runs of the Circle route, but never 

 dominant on more than 6 of 11 monthly samples of each of the other routes. This 

 route was characterized by more cropland and low grassland than the other routes 

 (table 5), and appeared to provide optimal horned lark habitat yearlong. Other 

 species which were among the two most abundant for this route only were the rock 

 dove, which uses bridges near cropland as nest support structures and is dependent 

 on waste grain, and hence is abundant near cropland along this route; the chestnut- 

 collared longspur, a grassland species closely associated with the horned lark; 

 and the starling, ohe house sparrow, and lark bunting. The Flowing Well route 

 was the only route having the cliff swallow as a dominant. This species and the 

 western meadowlark were the two dominants for all three breeding-season runs. 

 The rock wren, common in badland and scoria habitats along this route, was 

 among the two dominant species only during the August run of this route. The 

 black-billed magpie was second dominant during December through March runs. 

 The ring-necked pheasant and the Bohemian waxwing were dominant only on certain 

 runs of the Prairie Elk route where the mourning dove was dominant during July. 

 The Missouri River route was distinguished by co-dominance by red-winged black- 

 birds during May and July runs. This route contained the most extensive habitat 

 for this species of all routes. The black-billed magpie, a fairly common and 

 conspicious yearlong resident of the cottonwood forests and tall shrub habitats 

 of the Missouri River floodplain, was dominant only on the February run of this 

 route. The Dreyer Ranch route was dominanted by the horned lark and co-dominated 

 by the western meadowlark in May. Dominance was reversed during the remaining 

 two runs. This route is characterized by typical upland grassland habitat favored 

 by these two species. 



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