Effects of Bison and Cattle Grazing on Milkweeds and Monarch Butterflies

Presenter Information

Grace ThomasFollow

Presenter Type

UNO Graduate Student (Masters)

Major/Field of Study

Biology

Advisor Information

tdickson@unomaha.edu

Location

CEC RM #127

Presentation Type

Oral Presentation

Start Date

22-3-2024 9:00 AM

End Date

22-3-2024 10:15 AM

Abstract

Monarch butterflies have experienced massive population declines and are being considered for listing under the U.S. Endangered Species Act. This has inspired conservation efforts to mitigate these declines. One of the primary conservation efforts has been to try to increase milkweed (Asclepias spp.) abundance. Milkweeds are the required host plant for monarch caterpillars, and the spread of row-crop agricultural lands has contributed to the deterioration of milkweeds. Previous research by my advisor, Timothy Dickson, indicates that cattle grazing dramatically decreases milkweed abundance, which is important because 34% of the continental USA is grazed by livestock, primarily cattle. However, bison grazing, which occurs on many conservation sites and some beef production sites, may have less adverse effect on milkweed than cattle grazing. My project will compare and quantify grazing impacts on milkweed densities and juvenile monarch abundances among bison-grazed, cattle-grazed, and ungrazed lands. The project will build upon previous research by comparing juvenile monarch abundance between grazed and ungrazed lands and by comparing lands grazed by bison and cattle.

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Mar 22nd, 9:00 AM Mar 22nd, 10:15 AM

Effects of Bison and Cattle Grazing on Milkweeds and Monarch Butterflies

CEC RM #127

Monarch butterflies have experienced massive population declines and are being considered for listing under the U.S. Endangered Species Act. This has inspired conservation efforts to mitigate these declines. One of the primary conservation efforts has been to try to increase milkweed (Asclepias spp.) abundance. Milkweeds are the required host plant for monarch caterpillars, and the spread of row-crop agricultural lands has contributed to the deterioration of milkweeds. Previous research by my advisor, Timothy Dickson, indicates that cattle grazing dramatically decreases milkweed abundance, which is important because 34% of the continental USA is grazed by livestock, primarily cattle. However, bison grazing, which occurs on many conservation sites and some beef production sites, may have less adverse effect on milkweed than cattle grazing. My project will compare and quantify grazing impacts on milkweed densities and juvenile monarch abundances among bison-grazed, cattle-grazed, and ungrazed lands. The project will build upon previous research by comparing juvenile monarch abundance between grazed and ungrazed lands and by comparing lands grazed by bison and cattle.