Ontario’s first butterfly reintroduction: a conservation success story

Posted onJune 6, 2024byShannon Underwood|Mottled Duskywing Butterfly, Native Pollinator Initiative, News and Events

WPC is working to bring the mottled duskywing back to Ontario as part of the Ontario Butterfly Species at Risk Team. Together, we are spearheading an innovative effort to reintroduce the duskywing to Pinery Provincial Park in southwestern Ontario.

The mottled duskywing reintroduction to Pinery Provincial Park began in 2021, and celebrated its fourth year of monitoring on May 6th, 2024! Since the beginning of this season, our team has been working incredibly hard to monitor the first generation of adult butterflies. Throughout the majority of its range in Ontario, the mottled duskywing only has one flight period, but historically in areas of southwestern Ontario, where it was once present- it had two generations. Incredibly, the reintroduced population at Pinery has reverted to two generations of adults throughout the summer!

This spring, the first generation of adults emerged from overwintering larvae (yes, overwintering!) in the beginning of May, which produced the earliest flight records in Ontario! They are expected to fly until mid-June, a time in which they will mate and females will lay eggs. Some of the resulting caterpillar larvae from the first generation will mature into adults in July and produce the second flight generation, while other caterpillars from the first generation will enter diapause (a period of suspended development). For those that go on to produce the second generation of mottled duskywings adults, the offspring of these butterflies will also enter diapause and spend the upcoming winter tucked away in little leaf nests. How cool is that! How do they know how to do this?! Is this why I love them so much?

Mottled duskywing egg on leaf (left) and mottled duskywing caterpillar in leaf nest (right)

From the initial reintroduction into the park in 2021 until now, the Ontario Butterfly Species at Risk Recovery Team has released over 1400 mottled duskywing pupae, caterpillars, and adults throughout Pinery. Over the course of these 4 years, we have learned a lot like which release treatments and which locations this butterfly responds to the best.

I first started working on this project 2 years ago, which was the beginning of monitoring efforts for the mottled duskywing after its initial reintroduction in 2021. This year has been the first year I have been able to participate on this project since, and my two working experiences could not be any more different from each other! What was once a small population of mottled duskywings at Pinery in 2022, has established into a much larger population in the park over these last few years.

On my way to catch all of the mottled duskywing in 2022!

In 2022, it was normal for our recovery team to sight a mottled duskywing sporadically every few days. The record number sighted during one survey that season was 4 adults on May 25th, 2022. On May 20th, 2024, we made history when we sighted an incredible 27 mottled duskywings in one survey, and then another 19 the next day! It has not been uncommon this year for our recovery team to sight over 10 mottled duskywings during a single survey for the first flight generation.

To give you some more perspective on how well the mottled duskywing has been establishing at Pinery: at our most successful release site in 2022, our team only observed around 50 mottled duskywings flying in the first and second generation combined. While those numbers seemed incredibly exciting at the time- comparatively to this year, we have early estimates of a population of 200 individuals for the first generation alone, at this same site! This is the most plentiful population estimate we have had to date on this project.

To say the least, it has been a positive shock for me to walk through the same trails that I did just 2 years ago, but now instead I see such a significant increase in the abundance of mottled duskywings flying around and of the host plants as well! I feel incredibly connected to this butterfly and to its reintroduction at Pinery Provincial Park because I have first-hand witnessed the success of this conservation effort, which is a huge milestone in any ecology career.

It is truly inspiring to see such positive numbers for the mottled duskywing only after 4 years of effort, and we are extremely hopeful for its future and for this population at Pinery to become self-sustaining! Our team is excited to continue to monitor even more mottled duskywings this season, and in the years to come. This is evidence that conservation efforts work!

Our team working hard in the field to monitor this year’s populatino of mottled duskywings.

The continued success we are seeing from this project is a result of incredible long-term effort made by many collaborative partners such as Wildlife Preservation Canada, NRSI, Cambridge Butterfly Conservatory, University of Guelph, and of course, our friends at Pinery Provincial Park. Pinery Provincial Park is home to many endangered species, just like the mottled duskywing, who depend largely on its abundance of rare oak savanna habitat. The reintroduction of the mottled duskywing into Pinery could not be successful without the resource managers who use multifaceted strategies to uphold the park’s ecological integrity. Efforts like prescribed burns and deer herd management have directly encouraged the growth of many important plant species, just like the mottled duskywing host plants: New Jersey Tea and Prairie Redroot. Pinery Provincial Park is truly a unique and beautiful landscape that is hard to properly represent through pictures and words. I feel incredibly lucky for the opportunities to work with this land and to be able to call it one of my homes.

Below: field of mottled duskywing host plant in rare oak savannah (left) and the dynamic dunes of Pinery (right)

Shannon Underwood

2024 Crew Lead- Mottled Duskywing Pinery Reintroduction Program at Pinery

Shannon Underwood is a graduate from University of Toronto where she studied Conservation and Biodiversity. She is fascinated by nature and loves learning new things. She has great interest in working with species-at-risk and with ecosystem restoration. She is excited to pursue her passion for the outdoors in the field of conservation.