Interactive effects of severe drought and grazing on the life history cycle of a bioindicator species

Abstract

We used the lesser prairie‐chicken (Tympanuchus pallidicinctus), an iconic grouse species that exhibits a boom–bust life history strategy, on the Southern High Plains, USA, as a bioindicator of main and interactive effects of severe drought and grazing. This region experienced the worst drought on record in 2011. We surveyed lesser prairie‐chicken leks (i.e., communal breeding grounds) across 12 years that represented 7 years before the 2011 drought (predrought) and 4 years during and following the 2011 drought (postdrought). Grazing was annually managed with the objective of achieving ≤50% utilization of aboveground vegetation biomass. We used lek (n = 49) count data and covariates of weather and managed grazing to: (a) estimate long‐term lesser prairie‐chicken abundance and compare abundance predrought and postdrought; (b) examine the influence of annual and seasonal drought (modified Palmer drought index), temperature, and precipitation on long‐term lesser prairie‐chicken survival and recruitment; and (c) assess and compare the influence of grazing on lesser prairie‐chicken population predrought and postdrought. Lesser prairie‐chicken abundance was nearly seven times greater predrought than postdrought, and population declines were attributed to decreased survival and recruitment. The number of days with temperature >90th percentile had the greatest effect, particularly on recruitment. The population exhibited a substantial bust during 2011 and 2012 without a boom to recover in four postdrought years. Adaptive grazing positively influenced the population predrought, but had no effects postdrought. Results suggest that the severe drought in 2011 may have been beyond the range of environmental conditions to which lesser prairie‐chickens, and likely other species, have adapted. Land management practices, such as grazing, should remain adaptive to ensure potential negative influences to all species are avoided. Increasing habitat quantity and quality by reducing habitat loss and fragmentation likely will increase resiliency of the ecosystem and individual species.

Multiscale occupancy of the Lesser Prairie-Chicken: the role of private lands in conservation of an imperiled bird

“…Our results did not support hypotheses for shifts in extent of occurrence in response to drought-related covariates. These patterns are commensurate with other work, which has demonstrated reductions in abundance as it related to drought but site occupancy was largely unchanged especially at these spatial scales (Ross et al 2016a, Fritts et al 2018. Therefore, management of landscape mosaics (Haukos and Zavaletta 2016) may be more influential than drought-related climatic patterns (Grisham et al 2016) at both spatial scales.…”

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

“…Increasing female survival during the breeding season, combined with improving recruitment is often a priority for lesser prairie‐chicken population management (Hagen et al 2009, 2013). Development of ranch‐scale heterogeneity (among pastures) may mitigate effects of grazing disturbance by providing pastures with quality nesting or brood‐rearing microhabitat (Fritts et al 2018). For example, a manager could prioritize nest success within certain pastures by applying specific grazing prescriptions.…”

“…Other pastures could then be grazed at levels convenient for livestock production or brood habitat. Adaptive grazing may promote heterogeneity among pastures following a deferred‐rotation grazing strategy (Merrill 1954) and ensure the presence of quality habitat as weather and climate amplify the negative effects of forage use on vegetation structure (Ross et al 2016 a , b ; Fritts et al 2018). At finer scales (i.e., within pasture), success of heterogeneity‐based grazing prescriptions may hinge on the development of interspersion of nesting, brooding, and nonbreeding habitats (Hagen et al 2009, Gehrt et al 2020).…”

“…A growing body of evidence describes how domestic grazers perceive, interact with, and affect their environment on the Great Plains (Launchbach and Howery 2005, Derner et al 2009, Allred et al 2011). Additional insights from experimental design focused on the effects of grazing disturbances on vegetation structure metrics empirically related to a wildlife species resource selection and fitness would also be valuable (Fritts et al 2018; Smith et al 2018; Milligan et al 2020 a , b ).…”

“…Typically, a negative relationship between lesser prairie‐chicken habitat quality and grazing disturbance is assumed, with recommendations generally including a light to moderate stocking rate or forage use (e.g., 33–50%; Hagen et al 2004, Kansas Natural Resources Conservation Service 2014). Short‐duration grazing at moderate grazing intensity (~50% forage use) was benign or beneficial to lesser prairie‐chicken nesting ecology and adult survival, respectively, in sand shinnery oak ( Quercus havardii ) ecosystems of southeastern New Mexico, USA (Fritts et al 2016, 2018). The effectiveness of managed grazing to create landscape heterogeneity, conditional on regional variation in precipitation, soils, and vegetation productivity, for conservation of lesser prairie‐chickens on private lands is poorly understood (Giesen 1994, Hagen and Elmore 2016, Hagen et al 2017).…”