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Federal Register / Vol. 86, No. 103 / Tuesday, June 1, 2021 / Proposed Rules
TABLE 2RANGEWIDE AND ECOREGIONAL ESTIMATED LESSER PRAIRIE-CHICKEN TOTAL POPULATION SIZES AVERAGED
FROM 2015 TO 2020, LOWER AND UPPER 90 PERCENT CONFIDENCE INTERVALS CI OVER THE 5 YEARS OF ESTIMATES, AND PERCENT OF RANGEWIDE TOTALS FOR EACH ECOREGION FROM NASMAN et al. 2020, P. 21. NO SURVEYS WERE CONDUCTED IN 2019Continued 5-Year average estimate
Ecoregion Rangewide Totals

We now discuss habitat impacts and population trends in each ecoregion and DPS throughout the range of the lesser prairie-chicken.
Southern DPS
Using our geospatial analysis, we were able to explicitly account for
27,384

habitat loss and fragmentation and quantify the current condition of the Shinnery Oak Ecoregion. Of the sources of habitat loss and fragmentation that have occurred, cropland conversion, roads, and encroachment of woody vegetation had the largest impacts on
5-Year minimum lower CI
15,690

5-Year maximum upper CI

Percent of total
59,981

100

land cover in the Southern DPS Table 3. Based on our nearest neighbor analysis, we estimated there are approximately 1,023,572 ac 414,225 ha or 27 percent of the ecoregion and the Southern DPS potentially available for use by lesser prairie-chicken Table 1.

TABLE 3ESTIMATED AREAS OF CURRENT DIRECT AND INDIRECT IMPACTS, BY IMPACT SOURCE, AND THE PROPORTION
OF THE TOTAL AREA OF THE SHINNERY OAK 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.
Shinnery Oak Ecoregion Southern DPS
Impact sources Cropland Conversion
Petroleum Production
Wind Energy Development
Transmission Lines
Woody Vegetation Encroachment
Roads

540,120
161,652
90,869
372,577
617,885
742,060

Total Ecoregion/Southern DPS Area

Based on population reconstruction methods, the mean population estimate ranged between about 5,000 to 12,000
males through 1980, increased to 20,000
males in the mid-1980s and declined to 1,000 males in 1997 Hagen et al. 2017, pp. 69. The mean population estimate peaked again to 15,000 males in 2006
and then declined again to fewer than 3,000 males in the mid-2010s.
Aerial surveys have been conducted to estimate lesser prairie-chicken population abundance since 2012, and results in the Shinnery Oak Ecoregion from 2012 through 2020 Service 2021, Figure 3.10 indicate that this ecoregion has the third highest population size Nasman et al. 2020, p. 21 of the four
Percent of ecoregion
Acres
ecoregions. Average estimates from 2015
to 2020 are 3,077 birds 90 percent CI:
170, 8,237, representing about 11
percent of the rangewide total Table 2.
Recent estimates have varied between fewer than 1,000 birds in 2015 to more than 5,000 birds in 2020 see also Service 2021, Appendix E, Figure E.7.
Northern DPS
Prairies of the Short-Grass/CRP
Ecoregion have been significantly altered since European settlement of the Great Plains. Much of these prairies have been converted to other land uses such as cultivated agriculture, roads, power lines, petroleum production, wind energy, and transmission lines.

14
4 2
10
16
19

3,850,209

Some areas have also been altered due to woody vegetation encroachment.
Within this ecoregion, it has been estimated that about 73 percent of the landscape has been converted to cropland with 7 percent of the area in CRP Dahlgren et al. 2016, p. 262.
According to our GIS analysis, 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 4. Based on our nearest neighbor analysis, we estimated approximately 1,023,894 ac 414,355
ha, or 16 percent of the ecoregion, is potentially available for use by lesser prairie-chicken Table 1.

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TABLE 4ESTIMATED AREAS OF CURRENT DIRECT AND INDIRECT IMPACTS, BY IMPACT SOURCE, AND THE PROPORTION
OF THE TOTAL AREA OF THE SHORT-GRASS/CRP 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.
Short-Grass/CRP Ecoregion Impact sources
Acres
Cropland Conversion
Petroleum Production

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2,333,660
248,146

Percent of ecoregion 37
4