Using Grazing to Manage Herbaceous Structure for a Heterogeneity‐Dependent Bird

Abstract

Grazing management recommendations often sacrifice the intrinsic heterogeneity of grasslands by prescribing uniform grazing distributions through smaller pastures, increased stocking densities, and reduced grazing periods. The lack of patch‐burn grazing in semi‐arid landscapes of the western Great Plains in North America requires alternative grazing management strategies to create and maintain heterogeneity of habitat structure (e.g., animal unit distribution, pasture configuration), but knowledge of their effects on grassland fauna is limited. The lesser prairie‐chicken (Tympanuchus pallidicinctus), an imperiled, grassland‐obligate, native to the southern Great Plains, is an excellent candidate for investigating effects of heterogeneity‐based grazing management strategies because it requires diverse microhabitats among life‐history stages in a semi‐arid landscape. We evaluated influences of heterogeneity‐based grazing management strategies on vegetation structure, habitat selection, and nest and adult survival of lesser prairie‐chickens in western Kansas, USA. We captured and monitored 116 female lesser prairie‐chickens marked with very high frequency (VHF) or global positioning system (GPS) transmitters and collected landscape‐scale vegetation and grazing data during 2013–2015. Vegetation structure heterogeneity increased at stocking densities ≤0.26 animal units/ha, where use by nonbreeding female lesser prairie‐chickens also increased. Probability of use for nonbreeding lesser prairie‐chickens peaked at values of cattle forage use values near 37% and steadily decreased with use ≥40%. Probability of use was positively affected by increasing pasture area. A quadratic relationship existed between growing season deferment and probability of use. We found that 70% of nests were located in grazing units in which grazing pressure was <0.8 animal unit months/ha. Daily nest survival was negatively correlated with grazing pressure. We found no relationship between adult survival and grazing management strategies. Conservation in grasslands expressing flora community composition appropriate for lesser prairie‐chickens can maintain appropriate habitat structure heterogeneity through the use of low to moderate stocking densities (<0.26 animal units/ha), greater pasture areas, and site‐appropriate deferment periods. Alternative grazing management strategies (e.g., rest‐rotation, season‐long rest) may be appropriate in grasslands requiring greater heterogeneity or during intensive drought. Grazing management favoring habitat heterogeneity instead of uniform grazing distributions will likely be more conducive for preserving lesser prairie‐chicken populations and grassland biodiversity. © 2021 The Wildlife Society.

Availability of lesser prairie‐chicken nesting habitat impairs restoration success

“…In the short term, continued maximum enrollment and retention of CRP remains the most straightforward way to avoid extirpation of lesser prairie-chicken populations in this ecoregion. In the long term, changes in grazing management, including reductions in grazing intensity and distribution through strategies such as growing season deferment, rest-rotation periods of at least a year, and increasing pasture size will likely be necessary to restore nesting habitat to private and public tracts of sand sagebrush prairie (Kraft et al 2021). Multi-year grazing deferments would also allow the regrowth of nesting cover and protect it from grazing and trampling between growing seasons.…”

Broad-scale changes in lesser prairie-chicken habitat

“…While our landcover configuration metrics alone may suggest lack of fragmentation, the change in total prairie area together with findings of increasing edge, loss of the largest prairie patches, and decline in prairie-dominated areas on the landscape indicates that fragmentation of lesser prairie-chicken habitat has in fact occurred in the Sand Sagebrush Prairie Ecoregion. Smaller patches of prairie, or even isolated CRP fields not bounded by native prairie, are less likely to provide the heterogeneous cover needed for each phase of the lesser prairie-chicken's life history including nesting, brooding, nonbreeding, and shelter from extreme weather [52,56].…”

Demographic effects of a megafire on a declining prairie grouse in the mixed‐grass prairie

“…We aged birds as either second‐year (SY) or after‐second‐year (ASY) based on wear and coloration of primary flight feathers (Ammann, 1944). All captured females were banded and given either a 22‐g Argos Satellite PTT transmitter (SAT‐PTT; PTT‐100, Microwave Technology) or a 15‐g bib style VHF transmitter (Advanced Telemetry Systems; Kraft et al, 2021; Robinson, Haukos, Plumb, Lautenbach, et al, 2018). We marked all captured females with transmitters because we were primarily interested in female survival and reproductive success as these contribute most to overall demographic rates of populations.…”

“…Demographic rates of lesser prairie‐chickens can be influenced by disturbances such as anthropogenic expansion, landscape fragmentation, grazing, and fire (Kraft et al, 2021; Lawrence et al, 2021; Robinson, Haukos, Plumb, Kraft, et al, 2018). Intensive grazing of grasslands can reduce herbaceous cover and decrease lesser prairie‐chicken nest survival rates (Kraft et al, 2021).…”

“…Demographic rates of lesser prairie‐chickens can be influenced by disturbances such as anthropogenic expansion, landscape fragmentation, grazing, and fire (Kraft et al, 2021; Lawrence et al, 2021; Robinson, Haukos, Plumb, Kraft, et al, 2018). Intensive grazing of grasslands can reduce herbaceous cover and decrease lesser prairie‐chicken nest survival rates (Kraft et al, 2021). Reduced adult and nest survival have been documented for greater prairie‐chickens ( Tympanuchus cupido ) occurring in areas with annual intensive burning and grazing practices, compared to patch‐burn grazing systems that mimic historic disturbance regimes (McNew et al, 2015; Winder et al, 2018).…”