Adaptive rangeland management benefits grassland birds utilizing opposing vegetation structure in the shortgrass steppe

Authors: DAVIS, KRISTIN - Colorado State University; Augustine, David; MONROE, ADRIAN - Colorado State University; Derner, Justin; ALDRIDGE, CAMERON - Colorado State University

Submitted to: Ecological Applications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2019
Publication Date: 1/1/2021
Citation: Davis, K., Augustine, D.J., Monroe, A., Derner, J.D., Aldridge, C. 2021. Adaptive rangeland management benefits grassland birds utilizing opposing vegetation structure in the shortgrass steppe. Ecological Applications. 30(1). Article e02020. https://doi.org/10.1002/eap.2020.
DOI: https://doi.org/10.1002/eap.2020

Interpretive Summary: Ranches make up a substantial amount of the land base in North America. These lands also support much wildlife, including many bird species of conservation concern. Some research suggests livestock grazing can be managed to benefit certain grassland bird species, but we need to better understand how and where this can be achieved. We evaluated how two grazing management systems – continuous, season-long grazing and adaptive, rest-rotational grazing – affected grassland bird abundance from 2013– 2017 in Colorado’s shortgrass steppe. We examined grazing impacts in conjunction with local soil and plant characteristics (i.e., ecological sites). When grazing management was evaluated in conjunction with spatial variation in ecological sites, we found two of our five focal bird species responded to grazing management: McCown’s longspur abundance decreased and grasshopper sparrow abundance increased in pastures rested from grazing for the entire previous year. In addition, abundances of all species varied across ecological sites. Our results show that effects of grazing management are dependent on local soil types, which need to be considered when developing grazing management for grassland birds. Adaptive drought mitigation practices, such as resting pastures for one year to generate grassbanks, may benefit grassland birds that prefer taller/denser vegetation structure but negatively affect species preferring shorter/sparser vegetation. In contrast, rotating intensive, shortduration grazing across the landscape in a single year might not create sufficient habitat for species that prefer short/sparse vegetation such as McCown’s longspur. Consideration of vegetation/soil characteristics and precipitation conditions can inform how adaptive management is applied on a landscape to benefit the full suite of breeding grassland birds. Ultimately, cattle production on rangelands can continue to support human economic needs while also supporting grassland bird populations in the shortgrass steppe.

Technical Abstract: Rangelands are temporally and spatially complex socio-ecological systems on which the predominant land use is livestock production. In North America, rangelands also contain approximately 80% of remaining habitat for grassland birds, a guild of species that has experienced precipitous declines since the 1970s. Some evidence suggests livestock grazing can be managed to benefit certain grassland bird species by generating the vegetation structure and density they prefer. These benefits, however, appear to be ecosystem-specific, are equivocal even for species predicted to benefit from grazing (e.g., those that prefer short, sparse vegetation), and are poorly understood for species breeding in the shortgrass steppe. We evaluated how two grazing management systems – continuous, season-long grazing and adaptive, rest-rotational grazing – affected grassland bird abundance from 2013– 2017 in Colorado’s shortgrass steppe. We examined grazing impacts in conjunction with local soil and plant characteristics (i.e., ecological sites). When grazing management was evaluated in conjunction with spatial variation in ecological sites, we found two of our five focal bird species responded to grazing management: McCown’s longspur abundance decreased and grasshopper sparrow abundance increased in pastures rested from grazing for the entire previous year. In addition, abundances of all species varied across ecological sites. Our results suggest grazing impacts on grassland birds may be context-dependent and managers should consider local environmental conditions (e.g., ecological sites) when developing grazing management for grassland birds. Adaptive drought mitigation practices, such as resting pastures for one year to generate grassbanks, may benefit grassland birds that prefer taller/denser vegetation structure but negatively affect species preferring shorter/sparser vegetation. In contrast, rotating intensive, shortduration grazing (i.e., one component of our rotational treatment) across the landscape in a single year might not create sufficient habitat for species that prefer short/sparse vegetation in our system (e.g., McCown’s longspur). Consideration of vegetation/soil characteristics and precipitation conditions can inform how adaptive management is applied on a landscape to benefit the full suite of breeding grassland birds. Ultimately, cattle production on rangelands can continue to support human economic needs while also supporting grassland bird populations in the shortgrass steppe.