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Federal Register / Vol. 86, No. 103 / Tuesday, June 1, 2021 / Proposed Rules
when management practices produce or enhance the vegetative characteristics required by the lesser prairie-chicken.
The interaction of fire and grazing and its effect on vegetation components and structure is likely important to prairiechickens Starns et al. 2020, entire. On properties managed with patch-burn grazing regimes, female greater prairiechickens selected areas with low cattle stocking rates and patches that were frequently burned, though they avoided areas that were recently burned Winder et al. 2017, p. 171. Patch-burn grazing created preferred habitats for female greater prairie-chickens if the regime included a relatively frequent fire-return interval, a mosaic of burned and unburned patches, and a reduced stocking rate in unburned areas avoided by grazers. When managed compatibly, widespread implementation of patchburn grazing could result in significant improvements in habitat quality for wildlife in the tall-grass prairie ecosystem Winder et al. 2017, p. 165.
In the eastern portion of the lesser prairie-chicken range, patch-burn grazing resulted in patchy landscapes with variation in vegetation composition and structure Lautenbach 2017, p. 20. Female lesser prairiechickens use of the diversity of patches in the landscape varied throughout their life cycle. They selected patches with the greatest time-since-fire and subsequently the most visual obstruction for nesting, and they selected sites with less time-since-fire and greater bare ground and forbs for summer brooding.
Livestock also inadvertently flush lesser prairie-chicken and trample lesser prairie-chicken nests Toole 2005, p. 27;
Pitman et al. 2006, pp. 2729. Brief flushing of adults from nests can expose eggs and chicks to predation and extreme temperatures. Trampling nests can cause direct mortality to lesser prairie-chicken eggs or chicks or may cause adults to permanently abandon their nests, ultimately resulting in loss of young. Although these effects have been documented, the significance of direct livestock effects on the lesser prairie-chicken is largely unknown and is presumed not to be significant at a population scale.
In summary, domestic livestock grazing including management practices commonly used to benefit livestock production has altered the composition and structure of grassland habitat, both currently and historically, used by the lesser prairie-chicken. Much of the remaining remnants of mixedgrass grasslands, while still important to the lesser prairie-chicken, exhibit conditions quite different from those
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prior to Euro-American settlement.
These changes have reduced the suitability of remnant grassland areas as habitat for lesser prairie-chicken.
Grazing management that has altered the vegetation community to a point where the composition and structure are no longer suitable for lesser prairiechicken can contribute to fragmentation within the landscape, even though these areas may remain as prairie or grassland. Livestock grazing, however, is not inherently detrimental to lesser prairie-chicken provided that grazing management results in a plant community diversity and structure that is suitable for lesser prairie-chicken.
While domestic livestock grazing is a dominant land use on untilled range land within the lesser prairie-chicken analysis area, geospatial data do not exist at a scale and resolution necessary to calculate the total amount of livestock grazing that is being managed in a way that results in habitat conditions that are not compatible with the needs of the lesser prairie-chicken. Therefore, we did not attempt to spatially quantify the scope of grazing effects across the lesser prairie-chicken range.
Shrub Control and Eradication Shrub control and eradication are additional forms of habitat alteration that can influence the availability and suitability of habitat for lesser prairiechicken Jackson and DeArment 1963, pp. 736737. Most shrub control and eradication efforts in lesser prairiechicken habitat are primarily focused on sand shinnery oak for the purpose of increasing forage for livestock grazing.
Sand shinnery oak is toxic if eaten by cattle when it first produces leaves in the spring and competes with more palatable grasses and forbs for water and nutrients Peterson and Boyd 1998, p.
8, which is why it is a common target for control and eradication efforts by rangeland managers. Prior to the late 1990s, approximately 100,000 ac 40,000 ha of sand shinnery oak in New Mexico and approximately 1,000,000 ac 405,000 ha of sand shinnery oak in Texas were lost due to the application of tebuthiuron and other herbicides for agriculture and range improvement Peterson and Boyd 1998, p. 2.
Shrub cover is an important component of lesser prairie-chicken habitat in certain portions of the range, and sand shinnery oak is a key shrub in the Shinnery Oak and portions of the Mixed-Grass Ecoregions. The importance of sand shinnery oak as a component of lesser prairie-chicken habitat in the Shinnery Oak Ecoregion has been demonstrated by several studies Fuhlendorf et al. 2002, pp. 624

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626; Bell 2005, pp. 15, 1925. In West Texas and New Mexico, lesser prairiechicken avoid nesting where sand shinnery oak has been controlled with tebuthiuron, indicating their preference for habitat with a sand shinnery oak component Grisham et al. 2014, p. 18;
Haukos and Smith 1989, p. 625; Johnson et al. 2004, pp. 338342; Patten and Kelly 2010, p. 2151. Where sand shinnery oak occurs, lesser prairiechicken use it both for food and cover.
Sand shinnery oak may be particularly important in drier portions of the range that experience more severe and frequent droughts and extreme heat events, as sand shinnery oak is more resistant to drought and heat conditions than are most grass species. And because sand shinnery oak is toxic to cattle and thus not targeted by grazing, it can provide available cover for lesser prairie-chicken nesting and brood rearing during these extreme weather events. Loss of this component of the vegetative community likely contributed to observed population declines in lesser prairie-chicken in these areas.
While relatively wide-scale shrub eradication has occurred in the past, geospatial data do not exist to evaluate the extent to which shrub eradication has contributed to the habitat loss and fragmentation for the lesser prairiechicken and, therefore, was not included in our quantitative analysis.
While current efforts of shrub eradication are not likely occurring at rates equivalent to that witnessed in the past, any additional efforts to eradicate shrubs that are essential to lesser prairie-chicken habitat will result in additional habitat degradation and thus reduce redundancy and resiliency.
Influence of Anthropogenic Noise Anthropogenic noise can be associated with almost any form of human activity, and lesser prairiechicken may exhibit behavioral and physiological responses to the presence of noise. In prairie-chickens, the boom call vocalization transmits information about sex, territorial status, mating condition, location, and individual identity of the signaler and thus is important to courtship activity and long-range advertisement of the display ground Sparling 1981, p. 484.
The timing of displays and frequency of vocalizations are critical reproductive behaviors in prairie grouse and appear to have developed in response to unobstructed conditions prevalent in prairie habitat and indicate that effective communication, particularly during the lekking season, operates within a fairly narrow set of acoustic conditions. Prairie grouse usually
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