The varied and beautiful species of butterflies that dot the western U.S. are being wiped out by the climate crisis, according to new research, and rising temperatures have helped cause a sharp decline in the number of butterflies in the U.S. last 40 years.
There has been a 1.6% reduction in the total number of butterflies observed west of the Rocky Mountain Range each year since 1977, the researchers calculated, equating to a staggering loss of butterflies over the study time period. .
“You extrapolate it and it sounds crazy, but it’s consistent with the anecdotal ‘windshield effect’ where people no longer waste time cleaning bugs off their car windshields,” said Matt Forister, professor of biology at the University of Nevada. and lead author of the study. .
“Certainly many species of butterflies are becoming so rare that it is difficult for some people to see what were once common and widespread species.”
The declines are stoking much-loved species like the monarch butterfly, which is known for its spectacular mass migrations to California each year, but has lost 99% of its population compared to 40 years ago. “With the monarch it looks like we are about to lose the migration, if not the species itself,” Forister said.
The investigation, posted in Science, analyzed citizen-collected butterfly sightings at 72 locations spanning every western state in the US In total, more than 450 species of butterflies were included in the study.
In all of these sightings, the researchers found a 1.6% annual drop in the number of butterflies in the west, which is consistent with the rate of decline for other insects. found by researchers in different parts of the world, fueling concerns of a deep crisis among the creatures that help supply much of our food, break down waste and form the crucial foundation of the web of life.
While butterflies, like other insects, are adversely affected by habitat loss and the use of toxic pesticides, the researchers took these factors into account in their study and found that global warming, even without those other pressures , is causing the steady decline of butterflies. .
This could be because the plants are drying out more rapidly in late summer, which means that nectar resources are scarcer for the butterflies, or that the warm winters are interfering with the state of stasis that the butterflies enter during the colder months, which means they are in worse condition when spring arrives.
“We have a lot of open ground in the west and people often have a hard time understanding that a few degrees of temperature can make a big difference, but they can,” Forister said. “We are seeing these impacts of climate change even in pleasant natural areas and my feeling is that the areas damaged by agriculture or urbanization have already been lost to the butterflies.”
Forister said that while temperatures will continue to rise, people can give butterflies a break by conserving areas full of wildflowers and reducing certain chemicals.
“The declines are extremely worrisome from an ecological point of view, said Dara Satterfield, a butterfly researcher at the Smithsonian Institute for Conservation Biology, who was not involved in the study. “We know that butterflies and moths act as pollinators, decomposers, nutrient transport vessels and food sources for birds and other wildlife.
“This study is consistent with other large data sets from around the world, showing us that the past decades have presented new obstacles to the survival of numerous species of butterflies.”
George is Digismak’s reported cum editor with 13 years of experience in Journalism