Around mid-summer, I begin wondering how the monarchs are doing. Last summer, in 2019, they were more numerous than usual in the Princeton area, and as I googled for news of their numbers in 2020, it was with the expectation that their population was on the upswing. Surprisingly, their overwintering numbers in the mountains west of Mexico City were down dramatically. The count comes out in March, just before they begin their journey north, and was down by half compared to the winter of 2018/19.
The low count this past winter was due in part to less than favorable migration weather last fall. Warm weather in the north delayed migration southward, and a drought in Texas left little nectar for the monarchs as they funneled through Texas on their way to Mexico. From Princeton, that flight is about 2500 miles, powered by the liquid sunlight of nectar.