Overview
Among Canada’s most endangered butterflies, the Mottled Duskywing (Erynnis martialis) is restricted to oak savanna and tallgrass prairie habitats, two of the country’s rarest and most threatened ecosystems. Like many endangered insects, its decline has been driven by habitat loss and fragmentation, leaving only a handful of isolated populations in southern Ontario. Understanding the ecological requirements of this species and developing effective recovery strategies has become a central focus of our research.
Since 2019, the Norris Lab has collaborated with Natural Resource Solutions Inc. (Jessica Linton), Cambridge Butterfly Conservatory, Alderville Black Oak Savanna, Wildlife Preservation Canada, the Ontario Butterfly Species at Risk Recovery Team, and numerous government and community partners to better understand the ecology, behaviour, genetics, and conservation of Mottled Duskywings. Our research combines long-term field monitoring, habitat assessment, population genetics, and experimental reintroductions to identify the factors that limit population persistence and recovery.
One of the primary objectives of this work has been to restore populations to areas where the species has disappeared. In 2021, we initiated the first-ever reintroduction of Mottled Duskywing at Pinery Provincial Park, where the butterfly had not been observed since the early 1990s. Through intensive post-release monitoring, we demonstrated that the reintroduced population successfully established, reproduced, and within just four years reached densities comparable to some of the largest remaining natural populations in Canada. This represents the first successful reintroduction of Mottled Duskywing and demonstrates that carefully planned, science-based translocations can be an effective tool for recovering endangered insect populations. Building on this success, reintroductions were expanded in 2024 to restored oak savanna habitats in Norfolk County along the north shore of Lake Erie.
Our research has also identified the habitat characteristics associated with successful reintroductions, providing practical guidance for future recovery efforts across the species’ range. Together, these studies are helping establish evidence-based approaches for conserving endangered insects while demonstrating that species recovery can restore both biodiversity and ecological function to Canada’s most threatened ecosystems.
A 2024 documentary that tells the story about our reintroduction of Mottled Duskywing to Pinery Provincial Park. Produced by Pinegrove Productions and narrated by Sarah Harmer.
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*Scroll past publications for additional photos of our Mottled Duskywing research.
Mottled Duskywing Publications
5. Polley, M**, Linton, JE, Brewster, A, MacKenzie, AS, Keyghobadi, N, Steiner, J, Kerekes, T & Norris, DR. 2026. Host plant patch size selection of an endangered butterfly, the Mottled Duskywing (Erynnis martialis), at a reintroduction site. In press: Journal of Insect Conservation
4. Polley, M, Linton, JE, Brewster, A, MacKenzie, AS, Keyghobadi, N, Steiner, J, Kerekes, T & Norris, DR. 2026. Reintroduction of an endangered butterfly, the Mottled Duskywing (Erynnis martialis). In press: Animal Conservation
3. Demarse, A, Trendos, E, Linton, JE, Flockhart, DTT, Brewster, A, Keyghobadi, N, Custode, L & Norris, DR. 2023. Phenology, population size, and factors influencing variation in density of an endangered butterfly, the Mottled Duskywing (Erynnis martialis). Endangered Species Research 50:195-208.
2. Henault, J, Linton, JE, Norris, DR & Westwood, R. 2022. Egg laying behavior and larval-shelter construction of the endangered Mottled Duskywing (Erynnis martialis). Journal of the Lepidopterists’ Society 76(1):43-55.
1. Kroeze, S, Brewster, A, Linton, JE, Norris, DR, Otis, G, Young, Y & Keyghobadi, N. 2022. Microsatellites for the at-risk Mottled Duskywing butterfly, Erynnis martialis. Conservation Genetics Resources 1:1.
Photos of Mottled Duskywing Research
