A Giant Swallowtail Butterfly’s Impressive Journey Northward

Two giant swallowtails
Credit: Espace pour la vie (Maxim Larivée)
Giant swallowtail
  • Giant swallowtail
  • Giant swallowtail
A Giant Swallowtail Butterfly’s Impressive Journey Northward

You may have noticed specimens of a very beautiful butterfly last summer. It’s one that’s hard to miss: the giant swallowtail is the largest butterfly in North America.

A research team to which Insectarium director Maxim Larrivée belongs has just shown that as a result of climate change and global warming, the giant swallowtail has extended the northern limit of its range faster than any other species of butterfly. A paper published in early March 2021 shows that over the last 18 years the geographic range of the giant swallowtail has expanded northward by 324 km. This is a remarkable phenomenon, as it’s 27 times faster than the usual speed of displacement of an organism affected by climate change. 

Looming reproductive problems for this butterfly

While climate conditions now favour the survival of this butterfly farther north, the same cannot be said of its host plant, the prickly ash, which its caterpillars feed on. Prickly ash hasn’t been moving north the same way the giant swallowtail has. In the medium term, that factor could even constitute a climate change adaptation problem for this butterfly or any other species whose host plants do not adapt at the same rate.

First discovered of the giant swallowtail at the Jardin botanique in 2012

Back in 2012, when the giant swallowtail was extending its range northward, the team at the Insectarium discovered a few specimens of the butterfly inside the Jardin botanique. Six caterpillars were found that turned into butterflies. That news about specimens of North America’s largest butterfly having been found in Québec made headlines around the world.

The giant swallowtail is now established in southern Québec. Every summer, Quebecers have an opportunity to observe North America’s largest butterfly. Its size and beauty are quite compelling. Some giant swallowtails have even been seen in Abitibi and the Gaspé—two regions that lie far beyond the range of the prickly ash, meaning that the butterfly wouldn’t be able to complete its life cycle there. 

Impossible without community science

Data on the giant swallowtail’s amazing journey were collected with the help of citizens fascinated by butterflies, as much of the information for the study was provided by the community science project eButterfly.

The paper “Climate Change and Local Host Availability Drive the Northern Range Boundary in the Rapid Expansion of a Specialist Insect Herbivore, Papilio cresphontes” was published in the scientific journal Frontiers on March 2, 2021.

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