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Federal Register / Vol. 86, No. 103 / Tuesday, June 1, 2021 / Proposed Rules
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events that are expected to lead to population collapse regardless of population health and for which adaptation is unlikely. Redundancy spreads the risk and can be measured through the duplication and distribution of resilient populations that are connected across the range of the species. The larger the number of highly resilient populations the lesser prairiechicken has, distributed over a large area within each ecoregion, the better the species can withstand catastrophic events. Catastrophic events for lesser prairie-chicken might include extreme drought; widespread, extended droughts; or a disease outbreak.
Measuring redundancy for lesser prairie-chicken is a difficult task due to the physiological and biological characteristics of the species, which make it difficult to survey and limit the usefulness of survey results. To estimate redundancy for the lesser prairiechicken, we estimated the geographic distribution of predicted available habitat within each of the four ecoregions and the juxtaposition of that habitat to other habitat and non-habitat.
As the amount of large grassland patches decreases and grassland patches become more isolated to reduce or preclude lesser prairie-chicken movement between them, the overall redundancy of the species is reduced.
As redundancy decreases within any representative ecoregion or DPS, the likelihood of extirpation within that ecoregion increases. As large grassland patches, the connectivity of those patches, and the number of lesser prairie-chicken increase, so does the redundancy within an ecoregion or a DPS.
Current Condition In the SSA report, we assessed the current condition of the lesser prairiechicken through an analysis of existing habitat; a review of factors that have impacted the species in the past, including a geospatial analysis to estimate areas of land cover impacts on the current landscape condition; a summary of the current potential usable area based upon our geospatial analysis;
and a summary of past and current population estimates. We also evaluated and summarized the benefit of the extensive conservation efforts that are ongoing throughout the lesser prairiechicken range to conserve the species and its habitat.
Geospatial Analysis Summary The primary concern for the lesser prairie-chicken is habitat loss and fragmentation. We conducted a geographic information system GIS

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analysis to analyze the extent of usable land cover changes and fragmentation within the range of the lesser prairiechicken, characterizing landscape conditions spatially to analyze the ability of those landscapes to support the biological needs of the lesser prairiechicken. Impacts included in this analysis were the direct and indirect effects of areas that were converted to cropland; encroached by woody vegetation such as mesquite and eastern red cedar Juniperus virginiana; and developed for roads, petroleum production, wind energy, and transmission lines. We acknowledge that there are other impacts, such as power lines or incompatible grazing on the landscape, that can affect lesser prairie-chicken habitat. For those impacts, either no geospatial data were available, or the available data would have added so much complexity to our geospatial model that the results would have been uninterpretable or not explanatory for our purpose.
There are several important limitations to our geospatial analysis.
First, it is a landscape-level analysis, so the results only represent broad trends at the ecoregional and rangewide scales.
Secondly, this analysis does not incorporate different levels of habitat quality, as the data do not exist at the spatial scale or resolution needed. Our analysis only considers areas as either potentially usable or not usable by lesser prairie-chicken based upon land cover classifications. We recognize that some habitat, if managed as high-quality grassland, may have the ability to support higher densities of lesser prairie-chicken than other habitat that exists at lower qualities. Additionally, we also recognize that some areas of land cover that we identified as suitable could be of such poor quality that it is of limited value to the lesser prairiechicken. We recognize there are many important limitations to this landscape analysis, including variation and inherent error in the underlying data and unavailable data. We interpreted the results of this analysis with those limitations in mind.
In this proposed rule, we discuss effects that relate to the total potential usable unimpacted acreage for lesser prairie-chicken, as defined by our geospatial analysis hereafter, analysis area. A complete description of the purpose, methodology, constraints, and additional details for this analysis is provided in the SSA report for the lesser prairie-chicken Service 2021, Appendix B, Parts 1, 2, and 3.

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Threats Influencing Current Condition Following are summary evaluations of the threats analyzed in the SSA report for the lesser prairie-chicken: Effects associated with habitat degradation, loss, and fragmentation, including conversion of grassland to cropland Factor A, petroleum production Factor A, wind energy development and transmission Factor A, woody vegetation encroachment Factor A, and roads and electrical distribution lines Factor A; other factors, such as livestock grazing Factor A, shrub control and eradication Factor A, collision mortality from fences Factor E, predation Factor C, influence of anthropogenic noise Factor E, fire Factor A; and extreme weather events Factor E. We also evaluate existing regulatory mechanisms Factor D and ongoing conservation measures.
In the SSA report, we also considered three additional threats: Hunting and other recreational, educational, and scientific use Factor B; parasites and diseases Factor C; and insecticides Factor E. We concluded that, as indicated by the best available scientific and commercial information, these threats are currently having little to no impact on lesser prairie-chickens and their habitat, and thus their overall effect now and into the future is expected to be minimal. Therefore, we will not present summary analyses of those threats in this document but will consider them in our overall conclusions of impacts to the species.
For full descriptions of all threats and how they impact the species, please see the SSA report Service 2021, pp. 24
49.
Habitat Degradation, Loss, and Fragmentation The grasslands of the Great Plains are among the most threatened ecosystems in North America Samson et al. 2004, p. 6 and have been impacted more than any other major ecosystem on the continent Samson and Knopf 1994, p.
418. Temperate grasslands are also one of the least conserved ecosystems Hoekstra et al. 2005, p. 25. Grassland loss in the Great Plains is estimated at approximately 70 percent Samson et al.
2004, p. 7, with nearly 93,000 square km 23 million ac; 9.3 million ha of grasslands in the United States lost between 1982 and 1997 alone Samson et al. 2004, p. 9. The vast majority of the lesser prairie-chicken range >95
percent occurs on private lands that have been in some form of agricultural production since at least the early 1900s. As a result, available habitat for grassland species, such as the lesser
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