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Climate change, habitat loss linked to sharp monarch butterfly decline


The monarch butterly population migrating to Mexico this year has been reduced to its lowest level ever recorded. The decline is likely due to global warming, habitat loss and the use of pesticides.


Gabriel Bouys

Monarch butterfly numbers have been reduced to their lowest levels ever recorded say scientists.

Scientists in Mexico, where the butterflies migrate during the winter, said that they have witnessed a 59 percent drop this year.

That's the lowest level since record-keeping began two decades ago, said Science World Report.

The survey was taken in Mexico in December and January.

Researchers found the drop while analyzing nine monarch colonies spanning over 2.9 acres.

The decline in population is likely due to a constellation of factors like climate change, wildfires, habitat loss and the use of certain pesticides, reported the Los Angeles Times.

Warmer temperatures have both caused wildfires that have destroyed their habitat but also caused milkweed to dry up, depriving the butterflies of their main food source.

The weed has also been destroyed by new techniques in farming, particularly genetically modified crops that can resist powerful herbicides that kill the milkweed, reported the New York Times.

The Times also reported that a sharp increase in farmland in the US has also taken away the grasslands that feed the monarchs.

The decrease in the monarch population can have serious ecological consequences.

A lack of pollinating insects can wipe out plant diversity with knock-on consequences for other animals and the planet.

"The fruits, nuts, seeds and foliage that everything else feeds on," Chip Taylor, director of Monarch Watch at the University of Kansas, told the Los Angeles Times.

"If we pull the monarchs out of the system, we're really pulling the rug out from under a whole lot of other species."