Monarch Population Status by Chip Taylor
As most of you know, the summer of 2015 produced a strong migration and a relatively large overwintering population (4.01 hectares). To place this population growth in context, let’s review the last several years. The population declined following each of the three growing seasons from 2011-2013. There were aspects of each season that account for these declines. For example, the temperatures from March through August in 2012 were warmer – actually hotter – than for any year going back to 1895. Monarchs arrived in the northern breeding area in good numbers in early May but altogether too early, and the hot/dry summer that followed dried up milkweeds and nectar sources leading to a significant decline in the migration and the overwintering population. In 2013, a cold period during the first three weeks of May restricted movement of the first generation monarchs produced in Texas and Oklahoma into the northern breeding range resulting in a much later than normal recolonization of this region. This pattern also led to a decline, with the lowest overwintering population on record (0.67 hectares). Conditions were somewhat better in 2014 and the population increased to 1.13 hectares in spite of the low numbers of overwintering monarchs returning to the South region.
