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An Evaluation of Idaho Roadside Habitats, Their Use by Monarch Butterflies and Other Pollinators, and Their Management

Project #: 4W8635
Start Date: 09/02/2020
End Date: 02/28/2023
Status: Completed

Graphic indicating the positive and negative impacts of roads and right of way maintenance/management such as mowing, weed management and toxins on pollinator insects such as bees and Monarch ButterfliesThe monarch butterfly population has declined drastically in western states since the 1980s, largely due to habitat loss and fragmentation. In Idaho, the Snake River Plain is a target location for conservation and restoration activities. ITD manages a large number of highway miles and adjacent right of way (ROW) acreage in this region, but there is little data on the amount of land or the specific locations that support butterfly populations, migration routes, and breeding habitat.

For this project, researchers from the Montana State University (MSU) Ecology Department and WTI’s Road Ecology program will conduct a field study to identify the amount and location of existing monarch butterfly habitat within ITD ROW land, as well as additional locations that could be easily restored to suitable habitat.  Monarchs and their host plants, milkweeds, are a key focus of the project, and it will also evaluate several other native butterflies and bee species that are of high conservation concern. From the findings, the research team will develop recommendations for ITD on how to manage roadsides that connect natural areas and conserve butterfly and bee populations. The research will be led by Dr. Diane Debiniski (MSU Ecology), in partnership with Rob Ament (WTI) and Dr. Laura Burkle (MSU Ecology).


The objectives of this project are to:

  • Identify the amount and location of existing suitable monarch butterfly, as well as other butterfly and bee pollinator habitats that currently exist in ITD ROWs in the project area.
  • Determine whether the hotspots on ITD interstate, primary and secondary ROWs correspond with locations of high quality habitat in adjacent lands.
  • Identify the amount and location of existing ITD ROWs in the study area that could be easily restored to provide habitat for monarch butterfly and other native butterfly and bee pollinator species.
  • Incorporate information regarding lands adjacent to, or within ITD’s ROWs where sightings of monarch butterfly adults, caterpillars or eggs have been documented.
  • Develop recommendations for the conservation and management of ITD roadsides with a focus on how ROWs can be restored or augmented so that they complement and connect natural areas to maximize their potential to conserve, restore and manage monarch butterflies, as well as other butterfly and bee pollinators and their habitats.