DW - Monarchs Down 15% From Last Year; Population Declines Every Year But Two Since 1996

[hatrack]

The monarch butterfly embarks on an impressive migration every year. But for the second year in a row, its numbers are declining — figures from an official Mexican government count in the winter of 2017 indicate a decrease of 14.7 percent from the year before. Apart from partial rebounds in the winters of 2001 and 2003, numbers have gone down steadily since 1996.

Storms and intense hurricane seasons disrupt the insect's routes and fell trees they rely upon for shelter. A wind storm and cold snap in March 2016 devastated the core of the butterfly reserve in Mexico. The massive overwintering colony was only discovered in 1975.

Pesticides used in the US also harm milkweeds, a plant intertwined with the monarch butterflies' life cycles. The US has set up some programs to help the monarch butterfly population grow again.

EDIT

http://www.dw.com/en/monarch-butterfly-numbers-decline-for-second-year-in-a-row/a-42847356

[democratisphere]

1. We must stop the destruction and extinction of plant, animal, insect and all life on this

planet to postpone the Sixth Mass Extinction which is inevitable.

[CentralMass]

2. Articles discussing the link between Roundup ready crops and the decline.

There are a number of researcher that think that the Monarch decline is "The canary in the coal mine" signaling the loss of biodiversity due to the increasing use of the Roundup ready crops and application of Roundup.

http://www.slate.com/articles/health_and_science/science/2014/01/monarch_butterfly_decline_monsanto_s_roundup_is_killing_milkweed.html

"For monarchs, the most important development was Roundup Ready corn and soybeans.

Since the turn of the century, these genetically modified crops have risen to dominance in the Midwest. Designed to withstand dousing from the Monsanto company’s Roundup weed killer, the plants enabled farmers to swiftly kill competing weeds, including milkweed, while leaving their crops untouched. In 2013, 83 percent of all corn and 93 percent of soybeans in the United States were herbicide tolerant, totaling nearly 155 million acres, much of it in the Midwest.

It’s no coincidence monarchs faltered at the same time. Karen Oberhauser, a conservation biologist at the University of Minnesota, and a colleague estimated that as Monsanto’s Roundup Ready corn and soybeans spread across the Midwest, the amount of milkweed in farm fields fell by more than 80 percent. Oberhauser determined that the loss of milkweed almost exactly mirrored the decline in monarch egg production."
“We have this smoking gun,” Oberhauser said. “This is the only thing that we’ve actually been able to correlate with decreasing monarch numbers.”

Soon there will be essentially no monarchs on cropland in the corn belt, according to some estimates. Already, Iowa farmland has lost more than 98 percent of the milkweed that was once there, according to Iowa State University biologist John Pleasants, who worked with Oberhauser. He’s seen firsthand the transformation as he has studied cornfields during the past decade and a half. Before Roundup, patches of milkweed grew among the corn and along the edges of fields. After the herbicide—nothing but corn.

https://www.motherjones.com/food/2012/03/researchers-gm-crops-are-killing-monarch-butterflies-after-all/

https://e360.yale.edu/features/tracking_the_causes_of_sharp__decline_of_the_monarch_butterfly

[ffr]

3. I'd say last year was another devastating year for Monarchs, from what I witnessed

15% down would be a low estimate. Of the five regional milkweed plant areas observed last year, covering ~2,000 square miles, if I remember correctly, there were no caterpillars last year. I did observe one failed chrysalis, one that turned black and should have hatched, but didn't.