Washington – The United States butterflies are disappearing due to insecticides, climate change and habitat loss, with the number of winged beauties 22% since 2000, according to a new study.
The first systematic analysis throughout the country of the abundance of butterflies found that the number of butterflies in the 48 lower states has been falling on average 1.3% annually since the change of the century, with 114 species that show significant decreases and only nine increasing, according to a study in the science of Thursday’s magazine.
“Butterflies have been decreasing the last 20 years,” said study co -author Nick Haddad, entomologist at Michigan State University. “And we see no sign that that will end.”
A team of scientists combined 76,957 surveys of 35 monitoring programs and combined them for a comparison of apples to apples and ended up counting 12.6 million butterflies over the decades. Last month, an annual survey that was seen only to monarch butterflies, to which federal officials plan List of threatened speciesCash a minimum almost all time less than 10,000, below 1.2 million in 1997.
Many of the decline species fell 40% or more.
David Wagner, an entomologist at the University of Connecticut who was not part of the study, praised his reach. And he said that while the annual rate of decrease may not sound significant, it is “catastrophic and sad” when it is aggravated over time.
“In just 30 or 40 years we are talking about losing half of the butterflies (and other insect lives) on a continent!” Wagner said in an email. “The tree of life is being denuded to unprecedented rates.”
The United States has 650 species of butterflies, but 96 species were so scarce that they did not appear in the data and 212 species were not found in a sufficient number to calculate the trends, said the main author of the Collin Edwards study, environmentalist and data scientist from the Washington Fishing and Wildlife Department.
“I am probably more concerned about the species that could not even be included in the analyzes” because they were very rare, said entomologist at the University of Wisconsin-Madison Karen Oberhauser, who was not part of the investigation.
Haddad, who specializes in rare butterflies, said in recent years that he has only seen two butterflies of Santa Francisco in danger of extinction, that only lives in a pump field in Fort Bragg in North Carolina – “Then it could be extinguished.”
Some known species had great drops. The Red Admiral, who is so quiet that he lands in people, has dropped 44% and the butterfly of the American lady, with two large backpacks on his rear wings, decreased 58%, Edwards said.
Even the Invasive butterfly of Col Blanca, “a species that is well adapted to invade the world,” according to Haddad, fell by 50%.
“How can that be?” Haddad wondered.
The expert in butterflies from the University of Cornell, Anurag Agrawal, said he cares more about the future of a different species: humans.
“The loss of butterflies, parrots and marsopas is, without a doubt, a bad sign for us, the ecosystems we need and the nature we enjoy,” said Agrawal, who was not part of the study, in an email. “They tell us that the health of our continent is not so good … Butterflies are an ambassador to the beauty of nature, fragility and interdependence of species. They have something to teach us. “
Oberhauser said that butterflies connect people with nature and that “it calms us, it makes us healthier and more happy and promotes learning.”
What is happening to the butterflies in the United States is probably happening to other insects less studied throughout the continent and the world, Wagner said. He said that this is not only the most complete butterfly study, but the richest in data for any insect.
Butterflies are also pollinating, although not as prominent as bees, and are an important source of pollination of Texas cotton cultivation, Haddad said.
The greatest decrease in butterflies was in the southwest, Arizona, New Mexico, Texas and Oklahoma, where the number of butterflies fell in more than half in the 20 years.
“It seems that butterflies that are in dry and warm areas are doing particularly badly,” Edwards said. “And that captures a lot from the southwest.”
Edwards said that when they looked at species of butterflies that lived in both the hottest and most cold north, the ones that improved were in the coldest areas.
Climate changeThe loss of habitat and insecticides tend to work together to weaken butterfly populations, Edwards and Haddad said. Of the three, it seems that insecticides are the biggest cause, based on previous investigations of the west of the United States, Haddad said.
“It makes sense because the use of insecticides has changed dramatically over time since our study began,” said Haddad.
Habitats can be restored and can also butterflies, so there is hope, Haddad said.
“You can do Changes in your backyard And in his neighborhood and in his state, ”said Haddad. “That could really improve the situation for many species.”
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