A new paper, “Monarch Habitat in Conservation Grasslands” (Lukens et al. 2020), provides estimates of monarch habitat and use by monarchs in Midwestern conservation sites. Grassland conservation has been well-studied, but we know little about how planting and management activities influence the quality of habitat for monarchs and how monarchs interact with these areas. As lead co-authors on the paper, Laura Lukens and Kyle Kasten sought to quantify milkweed density, nectar plant composition, and monarch use of habitat in 61 conservation grasslands across Minnesota, Iowa and Wisconsin. Study sites were a combination of Conservation Reserve Program restorations, USFWS Partners for Fish & Wildlife Program sites, and private restorations. Their methods followed the Integrated Monarch Monitoring Program (IMMP) protocols developed by the MJV in collaboration with the Monarch Conservation Science Partnership.

The authors observed four milkweed species across study sites, and at least one milkweed species was present at almost every site. Milkweed density ranged from 0-16,880 plants per hectare with a mean of 1,390 per hectare (563 plants per acre). Asclepias syriaca (common milkweed) was most frequently observed, regardless of whether or not it was planted. Asclepias incarata (swamp milkweed) and A. tuberosa (butterflyweed) appear to be more cost-effective (than A. syriaca or A. verticillata) to include in a seed mix, given that they were both more likely to be present and occurred at higher densities when planted than when not planted.

“Results of the study revealed a higher density of milkweed than previously estimated in similar site types,” said Laura Lukens, Monarch Joint Venture’s (MJV) National Monitoring Coordinator. “We have milkweed stem goals for bringing the monarch population to a sustainable level, and this helps us understand what is currently out there, and what kind of stem densities are achievable in this habitat type.”

The study also demonstrated a need for more early-flowering nectar sources, when monarchs arrive from an energy-intensive migration. Blooming plant frequency was lowest in the beginning of the season (late May-early June), suggesting that managers should consider adding early-flowering species to seed mixes and on existing conservation lands. “This action would not only help monarchs, but also an array of other species that depend on nectar for nutrition,” said Kyle Kasten, MJV’s Habitat Lead.

In a landscape transformed by agriculture and development, these conservation grasslands are an important source of existing and potential habitat for monarchs and other wildlife. The authors encourage future researchers and land managers to keep detailed records and to continue to build a robust dataset through the IMMP. Doing so will enable us to further understand the effectiveness of our conservation practices, enabling more effective and efficient conservation of habitat and pollinators.

To learn more or find out how you can take part in the IMMP, visit www.monarchjointventure.org/immp. Read the full paper here.

The content for the article was modified from the following paper:

Lukens L, Kasten K, Stenoien C, Cariveau A, Caldwell W and Oberhauser K (2020) Monarch Habitat in Conservation Grasslands. Front. Ecol. Evol. 8:13. doi: 10.3389/fevo.2020.00013

The Monarch Joint Venture is a national partnership of federal and state agencies, non-governmental organizations, businesses and academic programs working together to conserve the monarch butterfly migration. The content in this article does not necessarily reflect the positions of all Monarch Joint Venture partners. Header photo by Wendy Caldwell.