Date: 09/18/2020

Number: 500

Equally entertaining to the clouds of monarchs roosting in the Osage orange trees and nectaring on the seven son flower, are the half dozen immature Mississippi kites gorging themselves on monarchs after picking them out of the sky. The ground is littered with monarch wings.

I basically used the method of counting a visual extended hand circle and then tried to multiply that number times the number of circles I saw. I figured that there were approximately 200 in the trees roosting and another 300 or so in various other nearby trees and nectaring on a couple of seven son flower trees. 500 feels like a pretty conservative number. With all the other monarchs in the air nectaring at different places around the grounds, I wouldn't be surprised if the numbers were over a thousand if not in the thousands. But 500 would be a safe number for a short blip in time in a small 1/8 acre area of our 18 acre Arboretum.

To estimate numbers of butterflies preyed upon by the five kites, I counted roughly 120 wings this morning for an estimated 30 butterflies (4 wings/butterfly). Let's take a wild guess that with all the wings collected yesterday and this weekend, that there have been twice that number preyed upon for a total of 60 butterflies.

Today (9/23), with calm conditions they are moving on and there were only about 50 roosting and few nectaring this morning. Update at noon - I only counted a dozen...the migrating kites appear to have moved on as well.

[Uncertain when roost first formed] I noticed while camping that the south wind picked up to be a bit stiffer on Saturday the 19th which I'm guessing is when the fallout started.

Editor's note: report from another JN observer (KF) at this location suggests that the majority of the roost formed Sept 18 and lasted at least through Sept 22.

To read a more detailed report, check out my blog post:

Monarch Fallout and a Predator Story

Hesston, KS

Latitude: 38.1 Longitude: -97.4

Observed by: Brad
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