Arizona’s extreme heat threatens ‘spectacular migrations’ of butterflies

by Paola Boivin

By Kevinjonah Paguio
Cronkite News

SCOTTSDALE – This time of year, butterflies are in backyards and parks, but it may look different this season. This year’s extreme heat is expected to affect all parts of the ecosystem, including butterflies and their migration.

Climate change is prolonging heat cycles, according to the U.S. Environmental Protection Agency, making the period of extreme heat longer than in the past. The National Weather Service recorded 31 straight days of temperatures of 110° or higher in 2023 in Phoenix, a record. The heat took a toll on humans and other species they share the environment with, including butterflies.

Derek Kellogg, director of animal care at Butterfly Wonderland in Scottsdale, is concerned that “large and spectacular migrations” of butterflies are under threat.

Kellogg said that Arizona’s extreme heat has resulted in less food for butterflies and caterpillars. The heat has negatively impacted host and nectar plants that are integral to the butterflies’ survival. As a result, butterflies aren’t expected to migrate as far south as previous years.

Generally, monarch butterflies are in Arizona from October to April, according to the Desert Botanical Garden in Phoenix.

“The longer it stays warmer, the less likely they’re going to get that impulse to start migrating,” Kellogg said.

Butterflies are cold-blooded animals, and their body temperatures are reliant on the environment instead of a circulatory system.

“If the temperatures get extremely hot, they kind of just wilt or faint,” said Nina de l’Etoile, Butterfly Wonderland conservatory supervisor.

“A lot of people think there’s nothing really living in the desert,” de l’Etoile said, adding that most are not aware of “these seasons and cycles and systems that maintain all of these animals.”

“My educated guess would be that we’re going to have less flowering plants going into the fall, and we’ll see less butterflies,” de l’Etoile said.

According to the Xerces Society for Invertebrate Conservation, an international nonprofit conservation organization, 700 million monarch butterflies migrated from southern Canada and the northern United States to the southern U.S. and Mexico during the 1990s. Researchers estimate the population has decreased by more than 80%.

As winters in Arizona get warmer, Kellogg said the massive migrations of the past likely will become rarer, and fewer migration spectacles will be visible across the globe.

For more stories from Cronkite News, visit cronkitenews.azpbs.org.

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Two white peacock butterflies fly around Butterfly Wonderland on Sept. 20, 2023. “Everything’s just kind of ducking and covering during this harder time of the year,” Derek Kellogg, Butterfly Wonderland director of animal care, said in reference to Arizona’s record-breaking heat. (Photo by Kevinjonah Paguio/Cronkite News)
A tiger longwing butterfly balances itself on a leaf at Butterfly Wonderland on Sept. 20, 2023. The number of butterflies migrating through Arizona is expected to decrease due to the state’s extreme heat negatively affecting their food sources. (Photo by Kevinjonah Paguio/Cronkite News)
Derek Kellogg tags and records butterflies at Butterfly Wonderland on Sept. 20, 2023. Kellogg says that Arizona’s extreme heat has resulted in less food for butterflies and their caterpillars. (Photo by Kevinjonah Paguio/Cronkite News)
A paper kite butterfly feeds on a flower at Butterfly Wonderland on Sept. 20, 2023. “If the temperatures get extremely hot, they kind of just wilt or faint,” Nina de l’Etoile, Butterfly Wonderland conservatory supervisor, said. (Photo by Kevinjonah Paguio/Cronkite News)
A malachite butterfly rests atop a leaf at Butterfly Wonderland on Sept. 20, 2023. Derek Kellogg, Butterfly Wonderland director of animal care, predicts that Arizona’s extreme heat this year will mean fewer butterflies migrating through the state. (Photo by Kevinjonah Paguio/Cronkite News)
A spotted tiger glassywing butterfly rests atop a flower at Butterfly Wonderland on Sept. 20, 2023. Arizona’s prolonged extreme heat is expected to reduce butterflies’ food, resulting in fewer migrating butterflies, Nina de l’Etoile, Butterfly Wonderland conservatory supervisor, said. (Photo by Kevinjonah Paguio/Cronkite News)
Oscar Rivera admires a butterfly at Butterfly Wonderland on Sept. 20, 2023. Families and elementary school students visit the conservatory to learn about and see these colorful animals. (Photo by Kevinjonah Paguio/Cronkite News)
Derek Kellogg, Butterfly Wonderland director of animal care, releases butterflies into Butterfly Wonderland’s indoor climate-controlled conservatory on Sept. 20, 2023. “The longer it stays warmer, the less likely they’re going to get that impulse to start migrating,” Kellogg said. (Photo by Kevinjonah Paguio/Cronkite News)
A Mexican kite swallowtail butterfly basks in the sun on Sept. 20, 2023. “A lot of people think there’s nothing really living in the desert,” said Nina de l’Etoile, Butterfly Wonderland conservatory supervisor, adding that most are not aware of “these seasons and cycles and systems that maintain all of these animals.” (Photo by Kevinjonah Paguio/Cronkite News)