State’s monarch butterflies critically low
SAN FRANCISCO >> The western monarch butterfly population wintering along California’s coast remains critically low for the second year in a row, a count by an environmental group released Thursday showed.
The count of the orange-and-black insects by the Xerces Society, a nonprofit environmental organization that focuses on the conservation of invertebrates, recorded about 29,000 butterflies in its annual survey. That’s not much different than last year’s tally, when an all-time low 27,000 monarchs were counted.
“We had hoped that the western monarch population would have rebounded at least modestly, but unfortunately it has not,” said Emma Pelton, a monarch conservation expert with the Xerces Society.
By comparison, about 4.5 million monarch butterflies wintered in forested groves along the California coast in the 1980s. Scientists say the butterflies are at critically low levels in the Western United States due to the destruction of their milkweed habitat along their migratory route as housing expands into their territory and use of pesticides and herbicides increases.
Researchers also have noted the effect of climate change. Along with farming, climate change is one of the main drivers of the monarch’s threatened extinction, disrupting an annual 3,000-mile (4828-kilometer) migration synched to springtime and the blossoming of wildflowers.
Western monarch butterflies head south to California each winter, returning to the same sites and even the same trees where they cluster to keep warm. The monarchs generally arrive in California at the beginning of November and spread across the country once warmer weather arrives in March.
On the eastern side of the Rocky Mountains, another monarch butterfly population travels from southern Canada and the northeastern United States across thousands of miles to spend the winter in central Mexico.