Wed. Nov 29th, 2023
Two butterflies mating on a plant.

A missing piece of Pinery Provincial Park’s biodiversity was recently replaced!

After a long absence, the Mottled Duskywing butterfly (Erynnis martial) takes flight again in one of the busiest parks in Ontario.

This is the story of how a little butterfly got lost and was returned home.

Pinery Oak Savanna

Pinery Provincial Park protects a rare type of habitat called oak savanna.

In this habitat, there are scattered trees (mostly fire-resistant oaks) with plenty of space between them so the sun can reach the smaller plants. This sunny opening allows many wildflowers to grow.

Oak savannahs were created and maintained (and in many places still are) through the use of fire by indigenous peoples. This type of land management creates incredible biodiversity, especially for butterflies.

When Pinery was added to the park system in 1957, the sparse trees were thought to indicate an unhealthy forest. Millions of pine trees were planted to fill the “gaps” in the forest.

The fire was rigorously extinguished. The white-tailed deer population increased dramatically as nearby settlers created conditions in which they thrived.

As the park’s tree canopy closed and deer ate almost every plant they could reach, life became more difficult for many species.

Restore critical habitat

By the late 1980s, ecologists and park managers were beginning to understand that oak savannas were a rare and valuable habitat.

But for many species it was already too late.

Butterflies were especially affected. Three savanna specialist species (the Mottled Duskywing, Karner Blue, and Eastern Persius Duskywing butterflies) disappeared from the Pinery in the early 1990s.

A butterfly on a yellow flower.A marked female with dark mottled wings. Each captured butterfly is assigned a unique color combination so researchers can identify it. Photo: A. Demarse

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The Mottled Duskywing is now listed as Endangered in Ontario, while the others have completely disappeared from the province and are considered extirpated.

Since then, Pinery staff have dedicated countless hours to oak savannah restoration projects.

Pinery staff have partnered with Kettle and Stony Point First Nation to manage the deer population. A prescribed burning program helps keep the tree canopy open. Seeds of key wildflower species have been spread to increase their populations and invasive species are continually removed.

But no habitat restoration would bring back the missing butterflies.

Bring on the butterfly superheroes

The dark-winged spotted butterflies still lived in some small pockets of habitat in Ontario, but they are far from Pinery.

Before colonization, southern Ontario had enough savanna habitats that the small insects could propagate on their own.

Today, our roads, agricultural fields, and mowed lawns have created insurmountable barriers for many species.

Group of scientists outdoors looking at materials.Ontario’s At-Risk Butterfly Species Recovery Team is hard at work. Photo: Ontario Butterfly Species at Risk Recovery Team

To get the Mottled Duskywings back, humans would have to lend them a hand.

The Ontario Butterfly Species at Risk Recovery Team was created for precisely this purpose.

After years of preparation, the team released just under 700 Mottled Duskywing individuals into the park in 2021.

Left: captive-bred butterflies.  Right: Ecologist holding a butterfly before releasing it. Left: captive-bred butterflies. Right: A tagged Mottled Duskywing butterfly captured at Pinery. Photos: E. Trendos

Shortly after their release, female butterflies were seen laying eggs on their host plants, New Jersey tea (American Ceanothus) and narrow-leaf New Jersey tea (Herbaceous Ceanothus).

As the summer of 2021 ended, the recovery team eagerly awaited the return of spring.

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If Mottled Duskywing butterflies survived the winter to emerge and breed in 2022, there would be a good chance the species could survive long-term.

Will our butterflies survive?

Finally, some of the first results sent to iNaturalist in May 2022 were confirmed: The butterflies had survived!

Left: Duskywing spotted eggs.  Right: a male marked Mottled Duskywing.Left: Duskywing’s speckled egg. Right: a male marked Mottled Duskywing. Photo: Ontario Butterfly Species at Risk Recovery Team

The recovery team’s work is not over. Researchers are taking advantage of this unique opportunity to study how long butterflies survive, how they respond to land management activities, and how far and how quickly they disperse from the release site.

The knowledge the recovery team gains from the newly released Pinery butterflies will be applied when they return Mottled Duskywings to several other planned sites.

If all goes well, this species will be much safer in Ontario and in time may no longer be considered endangered.

A species success story

It’s not just the butterflies that benefit from this work.

Thank you butterfly heroes! Photo: Ontario Butterfly Species at Risk Recovery Team

Birds, snakes, plants and other insects will also use the Pinery’s restored habitats.

And eventually, we may have the opportunity to return the three lost butterfly species to their rightful place in the park.

Ontario Parks would like to thank all partners of the Ontario Butterfly Species at Risk Recovery Team, including: Jessica Linton at NRSI, Cambridge Butterfly Conservatory, Norris Lab at the University of Guelph, Kawartha Land Trust, Lambton Wildlife Inc., Nature Conservancy of Canada, Toronto Zoo, Keyghobadi Laboratory at Western University, Wildlife Preservation Canada, Sheila R. Colla Native Pollinator Research Laboratory, Tallgrass Ontario and the Canadian Pollinator Service. Wild life.

Credit and our sincere thanks to A. Demarse for the beautiful header image of this post.