Forage and Habitat for Pollinators in the Northern Great Plains—Implications for U.S. Department of Agriculture Conservation Programs

Open-File Report 2020-1037
Prepared in cooperation with the U.S. Department of Agriculture
By: , and 



Managed and wild pollinators are critical components of agricultural and natural systems. Despite the well-known value of insect pollinators to U.S. agriculture, Apis mellifera (Linnaeus, 1758; honey bees) and wild bees currently face numerous stressors that have resulted in declining health. These declines have engendered support for pollinator conservation efforts across all levels of government, private businesses, and nongovernmental organizations. In 2014, the U.S. Department of Agriculture (USDA) and the U.S. Geological Survey initiated an interagency agreement to evaluate honey bee forage across multiple States in the northern Great Plains and upper Midwest. The long-term goal of this study was to provide an empirical evaluation of floral resources used by honey bees, and the relative contribution of multiple land covers and USDA conservation programs to bee health and productivity. Our multi-State analysis of land-use change from 2006 to 2016 revealed loss of grassland and increases in corn and soybean area in North and South Dakota, representing a significant loss of bee-friendly land covers in areas that support the highest density of summer bee yards in the entire United States. Our landscape models demonstrate the importance of the Conservation Reserve Program in providing safe locations for beekeepers to keep honey bees during the summer and highlights how land use in the northern Great Plains has a lasting effect on the health of honey bee colonies during almond pollination the subsequent spring. Our multiseason, multi-State genetic analysis of honey bee-collected pollen revealed Melilotus spp., Asteraceae, Trifolium spp., Fabaceae, Sonchus arvensis, Symphyotrichum cordifolium, and Solidago spp. were the top taxa detected; Melilotus spp. represented 42 percent of all detected taxa. Symphyotrichum cordifolium, Solidago spp., and Grindelia spp. were the top native forbs detected in honey bee-collected pollen. We also conducted plant and bee surveys on private lands enrolled in the Conservation Reserve Program and Environmental Quality Incentives Program. In general, we found significant variability in floral resources and pollinator utilization across USDA programs and practices. On average, greater than 75 percent of honey bee flower observations on private lands enrolled in a USDA conservation program were on non-native forbs, whereas 33 percent of wild bee flower observations were on non-native forbs. Melilotus officinalis and Medicago sativa were the most visited by honey bees, wherease Medicago sativa and Helianthus maximiliani were the most visited by wild bees. Our analysis of nectar dearth periods in June and September for honey bees revealed that although Melilotus officinalis and Medicago sativa were highly visited, less common native forb species such as Ratibida columnifera, Agastache foeniculum, and Gaillardia aristata were preferred species. However, these preferred species were relatively rare on the landscape and are, therefore, unlikely to make up a sizable part of the honey bee diet. In addition to our empirical results, we also showcase how the U.S. Geological Survey Pollinator Library, a decision-support tool for natural resource managers, can be used to design cost-effective seeding mixes for pollinators. Collectively, the results of this research will assist USDA with maximizing the ecological impact and cost-effectiveness of their conservation programs on pollinators in the northern Great Plains.

Suggested Citation

Otto, C.R.V., Smart, A., Cornman, R.S., Simanonok, M., and Iwanowicz, D.D., 2020, Forage and habitat for pollinators in the northern Great Plains—Implications for U.S. Department of Agriculture conservation programs: U.S. Geological Survey Open-File Report 2020–1037, 64 p.,

ISSN: 2331-1258 (online)

ISSN: 0196-1497 (print)

Study Area

Table of Contents

  • Acknowledgments
  • Abstract
  • Introduction
  • Landscape Suitability for Supporting Honey Bees
  • Honey Bee and Land-Use Pilot Study
  • Land-Use Effects on Honey Bee Colony Health and Services
  • Genetic Analysis of Bee-Collected Pollen Across the Northern Great Plains
  • Plant-Pollinator Interactions on Private Lands Enrolled in the Conservation Reserve Program or Environmental Quality Incentives Program
  • Floral Resource Limitations and Honey Bee Preference
  • The Pollinator Library—A Decision-Support Tool for Enhancing Pollinator Habitat
  • Summary
  • References Cited
  • Appendix 1. Bee Pollen Detection Data and Plant Taxa Information
Publication type Report
Publication Subtype USGS Numbered Series
Title Forage and habitat for pollinators in the northern Great Plains—Implications for U.S. Department of Agriculture conservation programs
Series title Open-File Report
Series number 2020-1037
DOI 10.3133/ofr20201037
Year Published 2020
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Fort Collins Science Center, Leetown Science Center, Northern Prairie Wildlife Research Center
Description Report: ix, 64 p.; Data Releases
Country United States
State Minnesota, North Dakota, South Dakota
Online Only (Y/N) N
Google Analytic Metrics Metrics page
Additional publication details