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type had both the highest density (106.1 pairs/100 ha) and the highest diversity 

 (16 species). The western meadowlark was the most abundant breeding bird in 

 three of the four major vegetation types (badlands, creek and sage-grassland). 

 They were outnumbered in the grassland type by horned larks and grasshopper 

 sparrows in 1979 and horned larks in 1980. A brief summary of the results for 

 each of the four major vegetation types follows: 



Sage-grassland 



1979 ; The results from the 1979 survey in this type indicated it contained 

 the highest breeding pair density (146.8 pairs/100 ha) and the second highest 

 diversity (nine species). An additional six species of birds were observed 

 on the sample strip, although no singing males were recorded for these species. 

 Meadowlarks were the most abundant breeding bird with an average of 52.2 pairs/ 

 100 ha. Lark buntings and Brewer's sparrows followed with averages of 38.6 

 palrs/100 ha and 27.2 pairs/100 ha, respectively. All three species reached 

 their greatest levels of abundance in the sage-grassland type. 



1980 ; Results from the 1980 survey revealed a decline of 73% in breeding bird 

 densities in the sage-grassland type. Density in this type was the lowest of 

 all types sampled (40.1 pairs/100 ha), as was diversity with five species. 

 Species with singing males on the strip that were recorded in 1979 but not 1980 

 were as follows: mourning dove, Sprague's pipit, lark bunting, grasshopper 

 sparrow and vesper sparrow. A major reason for the decline in density and 

 diversity observed in this type was the extreme drought compounded by the fact 

 that cattle were wintered on and adjacent to the strip. The combined effect 

 of these two factors was a drastic reduction of residual cover and vegetative 

 structural diversity. 



The Brewer's sparrow and clay-colored sparrow observed in this type are species 

 of "special interest or concern" for Montana. Destruction of the sagebrush 

 component in this type may result in a species density and composition resembling 

 that of the grassland type. A similar situation may exist in large grassy areas 

 with little sagebrush which are sometimes found in this type. 



Grassland 



1979: Breeding bird densities observed in this type were moderate (133.0 pairs/ 

 100 ha); however, diversity (six species) was low when compared with other types. 

 Lack of vegetative structural diversity as compared with other types probably 

 accounts for this, although the grasslands were in good condition with large 

 amounts of residual vegetation at the time of the survey. Horned larks were 

 the most abundant breeding bird in this type with an average of 35 pairs/100 ha. 

 They were followed by grasshopper sparrows and meadowlarks with densities of 

 34.3 pairs/100 ha and 29.3 pairs/100 ha, respectively. Relatively high breeding 

 densities of Sprague's pipits and chestnut-collared longspurs were recorded in 

 and for the most part confined to this type. 



1980: Breeding bird densities declined drastically (54%) to 61.6 pairs/100 ha 

 in 1980. Diversity, however, increased from six to eight species. This increase 

 was a result of one pair of vesper sparrows and a pair of Brewer's sparrows 

 which established territories on the strip. Horned larks were again the most 

 abundant breeding bird with a density approximately equal to that which occurred 



