Monarch Fall Roost
Sightings report image

Date: 10/09/2021

Number: 2000

There were south winds & very warm temperatures that kept the butterflies concentrated in pecan trees along the San Saba River for miles. We tagged 250 in an hour. The trees were dripping with butterflies!

[Additional information contributed by observer, added by Journey North, 10/12/21]:

We are in Menard County, along the San Saba River. I've been tagging monarchs here for 25 years. We are right on the yearly migration path. On October 2 & 3 light winds were out of the south with temperatures around 93 degrees. Way too hot for this time of year. Overnight Monday October 4 a north front moved in across the area. On Tuesday morning October 5 I went outside at 9:30am and there were monarchs fluttering over everywhere. The clouds were low and white with temperatures in the 70s so it was possible to see many, many of them. I watched for about an hour and it was constant. By 11:30, it got really warm and sunny and none were to be seen. That night we went along the river and were able to tag 27 before it got too dark. Winds turned from the south for the next 5 days which kept the butterflies clinging to the trees along the river. On 10-6, we tagged 38.On 10-7 we tagged 38 in the same location. Friday Oct 8 we went to that original spot in the afternoon and easily tagged 10 and could have done 30 or 40 more but ran out of time. Winds were still gusty from the south. Friday Oct 8 at 5:30 we went to a new spot along the San Saba River in a probably 100-200 acre pecan orchard. There were butterflies everywhere! 2 adults, a 6 year old and a 4 year old were catching them in nets, I tagged them, my husband recorded the sex. We tagged 185 from 5:45-7pm until we ran out of light.

I counted 15-20 in clusters hanging off the pecan leaves. There were clusters of them on 25+ trees. My estimate is probably not enough. We were in this pecan orchard from 5:45 - 7 both Friday night and Saturday night. They were not flying except fluttering around the trees as we walked through the orchard. There was a little nectaring on the small amount of frostweed growing. They were clustering in the pecan leaves 10-15 feet off the ground. There were more higher but our nets are only 12 feet tall. Temperatures were in the high 80s with southerly breeze. Ee discovered the roost 10-8. They were gone 10-11 after a small front came in the night before. Roosting mostly on Pecan trees in the good spot on the south side of the river. At the other spot we go to with great success they roost along the north side of the river on Pecan trees and Elm trees. Another great spot I go to is along a natural spring in a native pecan bottom and protected from all the wind.

Overnight temps and wind direction: south, temps in the high 50s, warming up to 80s in the daytime

Hext, TX

Latitude: 30.9 Longitude: -99.7

Observed by: Jenny
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