An article about monarch butterflies by Ernest Williams, the William R. Kenan Professor of Biology Emeritus, was recently published in the Adirondack Almanack (Saranac Lake, N.Y.).
In “2021 outlook for monarchs in the Adirondacks,” Williams discussed a recent report showing a decline in the number of monarchs overwintering in Mexico this year.
“Monarchs are in decline because of multiple threats throughout their life cycle: the loss of milkweed because of industrialized agriculture in their main midwestern breeding area; logging of the overwintering forests in Mexico; drought and loss of nectar sources due to climate change; and increasing severity of killing storms,” he wrote.
Williams also noted that due to the role that weather plays in their abundance, there is uncertainty about how many monarchs the area will see this year. Factors such as the prolonged cold in Texas could slow the growth of vital nectar sources, causing fewer monarchs to complete their northward migration. On the other hand, a summer of moderately warm weather in the north can help increase the number of eggs laid and therefore the number of adults.