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Federal Register / Vol. 86, No. 103 / Tuesday, June 1, 2021 / Proposed Rules
available as potential nesting habitat for lesser prairie-chicken Haukos et al.
2016, p. 285. Using our geospatial analysis, we were able to explicitly account for habitat loss and fragmentation and quantify the current condition of this ecoregion for the lesser prairie-chicken. Of the sources of habitat loss and fragmentation that have
occurred, conversion to cropland has had the single largest impact on land cover in this ecoregion Table 6. Based on our nearest neighbor analysis, we estimated there are approximately 1,028,523 ac 416,228 ha or 33 percent of the ecoregion, potentially available for use by lesser prairie-chicken Table 1. In addition, habitat loss due to the
degradation of the rangeland within this ecoregion continues to be a limiting factor for lesser prairie-chicken, and most of the existing birds within this ecoregion persist primarily on and near CRP lands. Drought conditions in the period 20112014 have expedited population decline Haukos et al. 2016, p. 285.

TABLE 6ESTIMATED AREAS OF CURRENT DIRECT AND INDIRECT IMPACTS, BY IMPACT SOURCE, AND THE PROPORTION
% OF THE TOTAL AREA OF THE SAND SAGEBRUSH ECOREGION ESTIMATED TO BE IMPACTED SEE TABLE 1 FOR
TOTALS
Impacts are not necessarily cumulative because of overlap of some impacted areas by more than one impact source.
Sand Sagebrush Ecoregion Impact sources Cropland Conversion
Petroleum Production
Wind Energy Development
Transmission Lines
Woody Vegetation Encroachment
Roads

994,733
163,704
0 167,240
68,147
446,316

Total Ecoregion Area

Based on population reconstruction methods, the mean population estimate for this ecoregion peaked at >90,000
males from 1970 to 1975 and declined to its lowest level of fewer than 1,000
males in recent years.
Aerial surveys from 2012 through 2020 indicate that this ecoregion has the lowest population size Nasman et al.
2020, p. 21 of the four ecoregions.
Average estimates from 2015 to 2020 are
Percent of ecoregion
Acres
1,215 birds 90 percent CI: 196, 4,547
representing about 4 percent of the rangewide lesser prairie-chicken total Table 2. Recent results have been highly variable, with 2020 being the lowest estimate reported. Although the aerial survey results show 171 birds in this ecoregion in 2020, with no confidence intervals because the number of detections were too low for statistical analysis, ground surveys in
32
5 0
5 2
14

3,153,420

this ecoregion in Colorado and Kansas detected 406 birds, so we know the current population is actually larger than indicated by the aerial survey results Rossi and Fricke, pers. comm.
2020, entire.
Table 7 combines the estimated area impacted presented above for each of the three ecoregions into one estimate for each impact source for the Northern DPS.

TABLE 7ESTIMATED AREAS OF CURRENT DIRECT AND INDIRECT IMPACTS, BY IMPACT SOURCE, AND THE PROPORTION
% OF THE TOTAL AREA OF THE NORTHERN DPS ESTIMATED TO BE IMPACTED SEE TABLE 1 FOR TOTALS
Impacts are not necessarily cumulative because of overlap of some impacted areas by more than one impact source.
Northern DPS
Impact sources Cropland Conversion
Petroleum Production
Wind Energy Development
Transmission Lines
Woody Vegetation Encroachment
Roads
Total Northern DPS Area

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Future Condition As discussed above, we conducted a geospatial analysis to characterize the current condition of the landscape for the lesser prairie-chicken by categorizing land cover data into potential usable, potential restoration, or non-usable categories, taking into account exclusion areas and impacts to
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remove non-usable areas. We further refined the analysis to account for connectivity by use of our nearest neighbor analysis as described in Rangewide Trends. We then used this geospatial framework to analyze the future condition for each ecoregion. To analyze future habitat changes, we accounted for the effects of both future
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Percent of DPS

Acres
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4,423,081
1,271,779
337,534
1,180,603
2,399,832
3,254,297

25
7 2
7 13
18

17,979,152

loss of usable areas and restoration efforts by estimating the rate of change based on future projections Service 2021, Figure 4.1.
Due to uncertainties associated with both future conservation efforts and impacts, it is not possible to precisely quantify the effect of these future actions on the landscape. Instead, we
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