Number of monarch butterflies has hardly changed over the past 25 years

(ORDO NEWS) — American ecologists have found that the number of monarch butterflies has remained relatively stable over the past 25 years, despite a sharp deterioration in wintering conditions in the southern regions of America. This was announced on Friday by the press service of the University of Georgia.

Observations in recent years show that the number of many insects, including butterflies, is rapidly declining. Several groups of ecologists immediately recorded a sharp decrease in the population of monarch butterflies (Danaus plexippus).

They attributed the decline to climate change and the use of herbicides that destroy the food base of butterflies.

“Fellows often talk about monarch butterflies being threatened with extinction, but we found that this is far from the case.

Many will disagree, but these butterflies are actually one of the most prosperous and widespread insect species in North America “, – said a researcher at the University of Georgia in Athens (USA) Andrew Davis, whose words are quoted by the press service of the university.

The researchers decided to find out how much the population of Danaus plexippus has declined over the past 30 years.

To do this, they analyzed the observations that their colleagues conducted from 1993 to 2018 in the United States. It turned out that the number of monarch butterflies on average has not actually changed, and in some regions of North America it has even increased in recent years.

According to scientists, climate change is affecting Danaus plexippus populations in two ways. On the one hand, warming worsens the conditions for their wintering in the south of North America, and on the other hand, hot summers in the USA and Canada accelerate the reproduction of butterflies after returning to the north.

“Southward migrations seem to have indeed become more difficult and deadly for monarchs, resulting in a reduction in their numbers at winter camps. On the other hand, butterflies compensate for these losses in the spring when they return north.

This suggests that a decrease in the size of their winter colonies is not an objective indication that Danaus plexippus populations are declining,” Davis concluded.


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