Incomprehension and dismay
at the Monarch Butterfly Fields

More than 4,000 milkweeds were shredded last week on federal land leased by Aéroports de Montréal

July 4, 2022

The Monarch Butterfly Fields made headlines last year following a project by Medicom to build a surgical mask materials factory on the site, a project that was later abandoned. Located north of the Dorval Golf Course, the Monarch Butterfly Fields are an abandoned 19-hectare area that has been left undeveloped and untouched since 2012 1, creating an invaluable ecological environment for both field fauna and flora, and for its connectivity to sections of wooded wetlands.

Monarch Fields destruction

The mowing spared nothing

We were dismayed to discover that the fields had been mowed in the middle of nesting season. The question arises: does this action violate the Migratory Bird Treaty in Canada and the United States 2 ? We know, thanks to eBird and our own observations, that 150 species of birds can inhabit the Monarch butterfly fields and Golf Dorval 3. Aéroports de Montréal (ADM)‘s own survey shows that Killdeer, Red-Winged Blackbirds, and Song Sparrows can nest at the site.4

Let’s also think about the potentially huge impact on other species of animals, such as snakes, mice, shrews, and marmots, as well as the multitude of insects, slugs and snails that, among other things, served as food for the birds and wildlife that had reappropriated this wilderness. Shrubs, flowers and plants that were sometimes more than three meters high were mowed down. Several Turkey vultures were on the ground demonstrating the deadly effect of the mowing.

More than 4,000 milkweed plants in bloom, surveyed in 2021, have disappeared from the landscape. Milkweed is an essential plant for the survival of the monarch butterfly. It is used by the butterfly to lay its eggs, and by the caterpillar as its primary food source before morphing into a chrysalis.

Milkweed seeding programs 5 are organized to help the monarch butterfly, whose population is declining, demonstrating the importance of this plant. It is important to note that in 2017, the City of Montreal was the first city in the province of Quebec to sign the Monarch Friendly City 6 commitment. But what will happen to the monarch butterflies during the fall migration?

vultures at Butterfly Fields

Increased presence of turkey vultures in the area after the mowing

The City of Montreal, which claims to be a leading city for biodiversity, will host the annual convention of the Ecological Society of America from August 14 to 19. In addition, Montreal will also host the COP15, from December 5 to 17, 2022. This major UN summit on biodiversity has been described by Steven Guilbault as “a prestigious event for Canada.” The Minister of Environment and Climate Change would have a great opportunity to demonstrate that Canada is concerned about biodiversity in urban areas by announcing that the federal lands north of the airport will be protected.

We would like to understand:

  • Why has ADM confirmed its decision to “maintain” all land leased to Transport Canada and zoned industrial from now on during nesting season ,and for what purpose?
  • When will Transport Canada and the federal ministry of the Environment and Climate Change decide to protect this unique site by modifying the ADM lease?
  • Why is this site, which would allow future generations of Montrealers to have access to nearby green spaces that facilitate the survival of biodiversity not already protected

We must act now to ensure that our green spaces are protected to ensure a healthy future to our children, our fauna and our flora.

groundhog inspecting damage to Monarch fields

A groundhog standing alone in a devastated habitat

So, what can a private citizen do to help move this issue forward? Write to your members of the Parliament to show your anger, dismay and disagreement with the destruction of a major portion of the second “green lung” of the island of Montreal. Also, explain to them that once a green space is destroyed, it will never be available again for our biodiversity and future generations.

For more information, contact TechnoparcOiseaux by email at

1 For reference see pages 14-38 of the Mémoire: Caractérisation écologique du Champ des monarques – Projet 81724
2 Loi de 1994 sur la convention concernant les oiseaux migrateurs (L.C. 1994, ch. 22)
3 10
4 Évolution Environnement. (2021, 30 juin). « Étude écologique: Projet de développement Chemin de l’Aviation (Dorval) pour Divco »
5 Fondation David Suzuki : Ensemble, créons un « effet papillon » pour la sauvegarde des monarques!

Images: courtesy of TechnoparcOiseaux
Feature image: L – Monarch Butterfly Fields, August 2021 and R – Monarch Butterfly Fields, June 25, 2022

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There are 7 comments

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  1. Irwin Rapoport

    This was a disaster brought upon us by the Aeroports de Montreal, which needlessly mowed the 19 hectares, taking out 4,000 plus milkweeds that are crucial for the survival of the Monarch butterfly, which is endangered and threatened. The monarchs lay their eggs on the milkweed plants, which provide a food source for the caterpillars and a place to cocoon and mutate into butterflies for the journey back to Mexico. The plants contain a toxin which protects the butterflies from predators.

    This action, which took down many species of plants, which provide food, shelter, and habitat for a wide variety of insects, birds, reptiles, and mammals, killed the milkweed plants as they were about to release their seeds, had caterpillars beginning to feed, and simply put this new generation of butterflies in flux and bewilderment.

    Make no mistake, the ADM knew what it was doing with this destruction. Their goal is to destroy the ecosystem so they can claim is there i nothing on the site and that they can develop the site without having to worry about environmental concerns. Richard III could not have planned this better.

  2. Irwin Rapoport

    The federal government can declare the 19 hectares hat make up the Monarch Fields a nature park/Monarch sanctuary right now. It is their land, which they lease to the ADM. We must demand that be done ASAP. There is is no time to lose.

  3. Jean Le Marquand

    This deliberate destruction of milkweed is nothing short of insanity and shows how little regard there is for saving bio-diversity in the Montreal area. It is unconscionable to knowingly wipe out an essential element in the survival of the Monarch butterfly as a species. If we cannot save one small but crucial space for this iconic species, we have failed miserably.

  4. Anne Streeter

    What a shocker! Such a no brainer to just do the right thing! Shame on the ADM, shame on the Liberal government and shame on Steven Guilbault!

  5. Georges R. Dupras

    Not to long ago I wrote a short note to the WestmoungMag on the issue of celebrating a victory not yet one (Major investor pulling out).

    In that piece, I asked why the government was so interested in this particular parcel of land, when so many other available sites, some with decaying structures, buildings that could benefit from a re-fit were left empty, costing taxpayers in so many ways. As expected, and having jumped through these hoops on many occasions before, I was not surprised that authorities, behind this project, did not respond to my concerns. Moreover, by refusing to operate in good faith, they have not only openly misled the people of Montreal but dismissed the opinions of thousands of North Americans and people worldwide. There is indeed more to this project that meets the eye, and a great deal more to it than our elected representatives are willing to divulge.

    It is long past due that our elected representatives be held accountable for their corporate affiliations and disrespect for the people.

  6. Sinikka Crosland

    To recklessly mow down the habitat of an endangered species should be considered criminal. We shouldn’t accept any excuses for such thoughtless, selfish and destructive behaviour.

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