When small, mottled-gray butterflies began appearing again among the sunlit wildflowers of Pinery Provincial Park, scientists and volunteers saw the payoff of years of habitat work and careful captive breeding. The mottled duskywing (Erynnis martialis), once absent from Pinery for decades, has now been reintroduced to the park and—after four years of releases and monitoring—shows clear evidence of in‑situ breeding.
The reintroduction was a coordinated effort that combined habitat restoration, captive rearing and experimental release methods. Since the project began in 2021, partners have released more than 1,400 captive‑reared mottled duskywing pupae, caterpillars and adults across several release sites inside Pinery, on the southeastern shore of Lake Huron. Field surveys in 2024 recorded adults, larvae and eggs, confirming that released individuals survived winter, emerged in spring and reproduced on host plants in the wild. ([wildlifepreservation.ca](https://wildlifepreservation.ca/2024-annual-report-interactive/))
Numbers that mean something
Monitoring crews documented strong early results: surveys turned up roughly 230 mottled duskywings in 2024, including sightings at every life stage and multiple observations of egg‑laying. Those findings show the program moved beyond simple augmentations toward establishing a self‑sustaining local population—an outcome the recovery team had only hoped for after years of intensive restoration and breeding work. ([wildlifepreservation.ca](https://wildlifepreservation.ca/2024-annual-report-interactive/))
What the science shows
Researchers published a detailed postrelease assessment that used four years of monitoring (2021–2024) to evaluate how different release strategies performed. That paper reports the Pinery reintroduction is the first documented reintroduction of this species in Ontario and shows that, at one site inside the park, densities exceeded 27 adults per hectare within four years through local reproduction. The study also tested which founder life stages (larvae, pupae or adults) produce the best outcomes—finding pupal and adult founders generally outperformed larvae in establishing the new population. ([zslpublications.onlinelibrary.wiley.com](https://zslpublications.onlinelibrary.wiley.com/doi/full/10.1111/acv.70038))
Restoring the right habitat
Experts emphasize that good reintroduction outcomes depend on more than numbers released. Pinery’s success followed years of work to restore oak‑savanna habitat—controlled burns, removal of planted pines, and reduction of deer browsing to allow key host plants such as New Jersey tea (Ceanothus spp.) to recover. Park managers and partners prepared the landscape so the reintroduced duskywings would encounter the resources they need to complete their life cycle. ([blog.ontarioparks.ca](https://blog.ontarioparks.ca/mottled-duskywing/))
How the project worked—and where it’s headed
The program pooled expertise and institutions: the Ontario Butterfly Species at Risk Recovery Team, Wildlife Preservation Canada, the Cambridge Butterfly Conservatory, university labs and Ontario Parks all contributed rearing, fieldwork and monitoring. Releases began in 2021 and continued through 2023 at multiple sites in Pinery; the 2024 surveys provided the first clear evidence that the released cohorts were producing the next generation. Because of the program’s early success, the team expanded releases to additional restored oak‑savanna sites elsewhere in southern Ontario beginning in 2024 and 2025. ([zslpublications.onlinelibrary.wiley.com](https://zslpublications.onlinelibrary.wiley.com/doi/full/10.1111/acv.70038))
“It is truly inspiring to see such positive numbers for the mottled duskywing so soon after four years of effort, and we are extremely hopeful for its future,” said Shannon Underwood, crew lead for the Pinery reintroduction program. ([wildlifepreservation.ca](https://wildlifepreservation.ca/2024-annual-report-interactive/))
Why this matters beyond one park
The mottled duskywing is assessed as endangered in Canada and in Ontario. That status reflects long declines across its range driven by habitat loss, succession, invasive species and other threats. The Pinery reintroduction provides a practical, peer‑reviewed model for how to combine habitat recovery with science‑based translocation techniques—knowledge that can be applied to other at‑risk butterflies and to sites where natural recolonization is blocked by modern landscapes. ([wildlife-species.canada.ca](https://wildlife-species.canada.ca/species-risk-registry/virtual_sara/files/cosewic/sr_hesperie_tachetee_mottled_duskywing_1213_e.pdf))
How people can help
Conservationists say long‑term success will depend on continued habitat management and monitoring. For people who want to support recovery work, practical options include supporting local conservation organizations, volunteering with habitat restoration projects and, where appropriate, creating pollinator‑friendly native plantings on private land to provide stepping stones between protected areas. Park and recovery‑team partners also rely on funding, citizen science observations and trained volunteers to sustain long‑term monitoring efforts. ([blog.ontarioparks.ca](https://blog.ontarioparks.ca/mottled-duskywing/))
The story of the mottled duskywing’s return to Pinery is a reminder that discrete, sustained actions—restoring habitat, breeding carefully, and monitoring results—can bring small, once‑lost species back to life. For a butterfly that depends on sunny, open oak savanna, the work is not finished. But after decades of absence, the sight of a tiny mottled wings beating among prairie‑flowers at Pinery is a small but tangible conservation victory.
