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Title:The influence of agricultural practices on avian abundance in Midwestern agricultural fields
Author(s):Wilcoxen, Cassandra Anne
Advisor(s):Ward, Michael P
Contributor(s):Benson, Thomas J; Walk, Jeffrey W; Villamil, Maria B
Department / Program:Natural Res & Env Sci
Discipline:Natural Res & Env Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Cover crop, Eastern Meadowlark, stopover, spring migration, cereal rye, migratory, grassland, tillage, organic, grass waterway, Conservation Reserve Program, row crop
Abstract:Row crop agriculture has become the predominant land use throughout the Midwest over the last century causing population declines in migratory and resident bird species. To mitigate these declines, we must understand the effect of current agricultural practices on species to make recommendations to farmers and land managers to help support bird populations. I evaluated the use of cover crops on agricultural fields during avian spring migration and evaluated in-field and edge-of-field practices during their breeding season. Cover crops are a fairly new agricultural practice being adopted at increasing rates throughout the Midwest, but the effect on bird species during their spring migration is unknown and unquantified. Bird surveys were conducted on four field types (corn stubble, corn stubble plus a cover crop, soybean stubble, and soybean stubble with a cover crop) during the spring of 2015 and 2016 in central Illinois to calculate relative bird abundance. To assess the value of the four field types for birds of conservation concern, an Avian Conservation Significance (ACS) value was calculated. Bird species richness and overall abundance were greater in cover crop fields compared to non-cover crop fields, with corn stubble plus a cover crop having the greatest overall bird abundance. Species that preferred cover crop fields were grassland species and a majority of species preferred corn stubble to soybean stubble. ACS values were greatest on cover crop fields, and in particular, on corn stubble plus a cover crop. ACS values were primarily driven by one grassland species, the Eastern Meadowlark (Sturnella magna), which is of high conservation concern and an early breeder to which cover crops could serve as an important resource during the early part of the breeding season. To understand the dynamics of in-field and edge-of-field practices on individual bird species, bird surveys were conducted during the breeding season of 2015 and 2016 throughout central Illinois. In-field practices were crop type, use of a cover crop, tillage usage, and organic management. Edge-of-field practices included the percentage of herbaceous mowed, woody linear, Conservation Reserve Program (CRP), water, and landscape, the amount of area in cash crop production surrounding a field. Overall bird abundance was most influenced by in-field practices and was greatest on wheat fields, no-till fields, fields with a cover crop, and organically managed fields. Wheat fields and cover crop fields may appear important for species because they provide early green habitat in the season that would be attractive to migrants. The most common edge-of-field practice in species’ top models was the percentage of CRP which on average made up <2% of the fields it was located on. ACS values were most influenced by in-field practices primarily wheat fields and an additive effect was achieved when in-field practices were paired with the edge-of-field practice, woody linear. ACS values during the breeding season were primarily driven by Dickcissel (Spiza americana), a grassland species of high conservation concern, and wheat fields were very important in supporting their abundance. This research is the first attempt into understanding which species use cover crop fields and in what abundances compared to non-cover crop fields under the most common management practices (cereal rye and herbicide termination). This research also furthers our understanding of how in-field and edge-of-field practices explain individual species relative abundances as well as how these practices influence birds of greater conservation concern.
Issue Date:2017-07-20
Rights Information:Copyright 2017 Cassandra Wilcoxen
Date Available in IDEALS:2018-03-02
Date Deposited:2017-08

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