The Monarchs reported in Peak Migration (October 6) did not remain on flowers overnight. At 22:00 I found about 100 in small roosts plus a few more of 1 to 5 individuals. Temp at sunset was around 70. When I check had dropped to between 60 and 65.
There are 47 in this image on under side of canopy of a large Ashe Juniper. There were a few more on this tree, out of frame. This was the largest group I found, but I didn't try to find all of them. Flash is harsh but time was 21:59 so no choice.
In general Monarch "roosts" here favor larger Live Oak (Quercus fusiformis not Q. virginiana) and Ashe Juniper (Juniperus Ashei) trees or groves. Sometimes mixed groves, or with other species. Typical of savanna trees, both these species when mature are wide and rounded and have most of the of the leaves on the outer canopy, leaving many bare twigs and branches underneath to grasp. Of course Monarchs will also use vines growing on the trees. (Dead greenbriar leaves look annoying like perching monarchs). And monarchs will roost on other trees that are available. This includes smaller trees and shrubs. Or tall grass and forbs. "Roosts" here do not seem to be the popular notion monarchs deliberately seeking other monarchs, but rather mostly seem to be the coincidence of individual Monarchs seeking the same type of shelter.
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