Volume 86, Issue 2 e22188
RESEARCH ARTICLE

Cattle grazing in CRP grasslands during the nesting season: effects on avian abundance and diversity

Benjamin S. Wilson

Benjamin S. Wilson

Department of Biological Sciences, Emporia State University, 1 Kellogg Circle, Emporia, KS, 66801 USA

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William E. Jensen

Corresponding Author

William E. Jensen

Department of Biological Sciences, Emporia State University, 1 Kellogg Circle, Emporia, KS, 66801 USA

Correspondence: William E. Jensen, Emporia State University, 1 Kellogg Circle, Emporia, KS 66801, USA.

Email: [email protected]

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Gregory R. Houseman

Gregory R. Houseman

Department of Biological Sciences, Wichita State University, 1845 Fairmount Street, Wichita, KS, 67260 USA

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Mary Liz Jameson

Mary Liz Jameson

Department of Biological Sciences, Wichita State University, 1845 Fairmount Street, Wichita, KS, 67260 USA

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Molly M. Reichenborn

Molly M. Reichenborn

Department of Biological Sciences, Wichita State University, 1845 Fairmount Street, Wichita, KS, 67260 USA

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D. Fraser Watson

D. Fraser Watson

Department of Biological Sciences, Wichita State University, 1845 Fairmount Street, Wichita, KS, 67260 USA

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Alex R. Morphew

Alex R. Morphew

Department of Biological Sciences, Wichita State University, 1845 Fairmount Street, Wichita, KS, 67260 USA

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Esben L. Kjaer

Esben L. Kjaer

Department of Biological Sciences, Wichita State University, 1845 Fairmount Street, Wichita, KS, 67260 USA

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First published: 19 January 2022
Citations: 3

Abstract

The Conservation Reserve Program (CRP) is a primary tool for restoring grassland in the United States, in part as wildlife habitat, which has benefited declining grassland bird populations. Among potential mid-contract management practices used to maintain early-successional CRP grasslands, cattle grazing had been prohibited and is currently disincentivized during the primary nesting season for birds (much of the growing season), despite the important role that large herbivores historically played in structuring grassland ecosystems. Conservative grazing of CRP grasslands could increase spatial heterogeneity in vegetation structure and plant diversity, potentially supporting higher densities of some grassland bird species and higher bird diversity. Our objective was to determine the effect of experimental cattle grazing on species-specific relative abundance and occupancy, species diversity, and community dissimilarity of grassland birds on CRP grasslands across the longitudinal extent of Kansas, USA (a 63.5-cm precipitation gradient) during the 2017–2019 avian breeding seasons. Fifty-three of 108 fields were grazed by cattle during the growing seasons of 2017 and 2018 and all fields were rested from grazing in 2019. For all analyses, we examined separate model sets for semiarid western versus more mesic eastern Kansas. Using data from line transect surveys, we modeled relative abundances of 5 songbird species: grasshopper sparrow (Ammodramus savannarum), dickcissel (Spiza americana), eastern meadowlark (Sturnella magna), western meadowlark (Sturnella neglecta), and brown-headed cowbird (Molothrus ater). Grazing had delayed yet positive effects on abundances of grasshopper sparrow in western Kansas, and eastern meadowlark in eastern Kansas, but negative effects on dickcissel abundance in western Kansas and especially on burned fields in eastern Kansas. Somewhat counterintuitively, brown-headed cowbirds in western Kansas were more abundant on ungrazed versus grazed fields in the years after grazing began. In addition, we modeled multi-season occupancy of 3 gamebird species (ring-necked pheasant [Phasianus colcicus], northern bobwhite [Colinus virginianus], mourning dove [Zenaida macroura]) and Henslow's sparrow (Centronyx henslowii); grazing did not affect occupancy of these species. In eastern Kansas, species diversity was highest in grazed, unburned fields. In western Kansas, bird communities in grazed and ungrazed fields were dissimilar, as determined from multivariate analysis. Though regionally variable, conservative stocking of cattle on CRP grasslands during the nesting season as a mid-contract management tool might increase bird species diversity by restructuring habitat that accommodates a greater variety of species and decreasing abundances of species associated with taller, denser stands of vegetation.

CONFLICTS OF INTEREST

The authors declare that there are no conflicts of interest.