Late Migrants and Population Size

Although there have been killing frosts over much of the northern portion of the breeding range, late monarchs have been reported with some regularity over the past two weeks and, as recently as yesterday (1 November), two monarchs were spotted headed in southerly directions in eastern Kansas. In spite of these reports, it appears that the movement of the main portion of the migration through eastern Kansas occurred over a shorter interval than in most years. This year the migration reached Lawrence, KS on 9 September and nearly all of the monarchs disappeared from the region around the 30th. We can usually count on being able to collect up to 30 monarchs per hour through 8 October but this was not the case this year when only a few monarchs could be found during the first week of October.

Based on all the reports received for the fall season and on the surveys such as that conducted by Dick Walton at Cape May, New Jersey, we’re still predicting that the monarch overwintering population will contain 80-100 million monarchs, a substantial improvement over the 28.3 million recorded last winter.