Monarch Population Status: Addendum

As an addendum to our Monarch Population Status report posted on 29 July 2014, I offer the following:

Reports from throughout the breeding range indicate an increase in monarch numbers roughly along the lines projected in May. The migration is already underway having started at 50 N around the 12th of August. The leading edge should be in southern MN at this time and in Ames, IA around the 6th of Sept. Fall roosts have been reported to Journey North in the Dakotas, MN, WI, MI and NY as of 28 August. No roosts had been recorded by the 29th of August last year (see Monarch Roosts Fall 2013 and Monarch Roosts Fall 2014). There will surely be more monarchs to tag over the next two months and the overwintering population in Mexico is certain to be larger. At a minimum, I expect the population to be twice as large as last year or roughly 1.4 hectares but it could be twice that size. We still have to hear about monarchs from many areas and the conditions during the migration will likely determine how many of the migrants reach the overwintering sites. It will help to watch the reports of overnight clusters recorded by Journey North and to watch the weather conditions and note the availability of nectar sources as monarchs migrate through the United States and northern Mexico.