Prescribed burns a gateway for bringing butterfly species back to Norfolk

The Mottled Duskywing butterfly (Erynnis martialis), an endangered species afforded protection under the Endangered Species Act (ESA), hasn’t been spotted in and around Backus Woods and St. Williams Forestry Reserve in Norfolk County since the late 1980s.

The endangered Mottled Duskywing butterfly. Photo: Jessica Linton

Like many butterflies, the Mottled Duskywing is selective about where it lives and what it eats. It relies on New Jersey Tea, a deciduous shrub, as its host plant. Their habitat in Ontario consists of rare and globally important habitats, such as tall grass prairie and oak savanna. Tallgrass prairie is first and foremost a grassland with minimal tree cover. Oak savannas are a grassland that is lightly forested, predominantly with oak trees. Both are dynamic environments with extremely high biodiversity and ecological benefits, however only about 3% of the historical coverage of tallgrass communities remains in Ontario.

These ecosystems benefit from low intensity fires, which rejuvenate the landscape by restoring nutrients to the soil and clearing away non-native and woody plants encroaching in these ecosystems. This is why prescribed fire is a common management tool done safely by licences professionals in tallgrass prairie habitats.

Due to the loss of this habitat over time in part through fire suppression, species such as the Mottled Duskywing have experienced reductions in populations.

The Open Country Working Group is working with the Ontario Butterfly Species at Risk Recovery Team. This Team is comprised of members from government departments, parks and conservation authorities, conservation organizations, academic institutions, relevant private organizations, as well as expert entomologists and restoration practitioners who are working across the province on the recovery of the Mottled Duskywing butterfly and restoration of the oak savanna and woodland habitats the Mottled Duskywing relies on.

New Jersey Tea is important for pollinators, is a nitrogen-fixer, and is the main food plant for the Mottled Duskywing butterfly. Photo: Mary Gartshore

In the LPWF, members of the Team are working with the Open Country Working Group to restore and enhance tallgrass prairie habitat on NCC lands identified as great candidate sites for reintroduction of the Mottled Duskywing. The Open Country Working Group, with funding from Canadian Wildlife Service, is actioning several stewardship activities include prescribed burns, conifer plantation management, removal of invasive species, and planting native wildflowers that provide a food source for pollinators. An emphasis has been placed on seeding of New Jersey Tea to support the Mottled Duskywing, although the stewardship activities on these sites within the Priority Place will support many other Species at Risk as well, including other arthropods, migratory birds, snakes, and more.

This project site is considered a significant and exciting part of a larger Mottled Duskywing recovery initiative because it involves creating habitat where it formerly existed, providing opportunities for future recovery activities.

The Recovery Team is planning its first reintroduction of the Mottled Duskywing to Pinery Provincial Park in 2021. This will be the first reintroduction of an endangered butterfly species in Ontario and paves the way for similar recovery activities in Norfolk County in the future.

Not only is this project setting the stage to bring back a species that was previously lost here, but it is also restoring and enhancing globally important ecosystems.

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