Flying
With the Butterflies
by Carol Cullar
February 27, 2003
 |
Here's an actual photo
of the front edge of the Valle de Bravo flow, which demonstrates the use of the warmth of the highway and the lowness of the butterflies' flight, using the lift created by "ground effect." Carol Cullar |
Just returned from an 8 day trip to the preserves around
Zitacuaro! Wanted to assure everyone that the monarchs are alive and well
and headed our way in just a few more days!
We visited 4 preserves: El Rosario, Chincua, Capulin,
and Valle de Bravo. For the last two days we were accompanied by Eligio
Garcia Serrano and experienced on two occasions (at Capulin and Valle
del Bravo) rivers of monarchs flowing down off the mountains using the
highway itself as a conduit to facilitate their flight.
Eligio said that in his ten years collecting data and monitoring the monarchs,
he had never before had the opportunity to observe such a movement!
The flow at Capulin was 90' wide, and we monitored the central flow in
a rectangle 15' x 30' and had a continuous rate of 40-45 PER SECOND. We
broke the 90' flow into 15' segments (except for the center segment of
30'): the flow dropped off in a bell curve and timed estimates from the
edges were between 0-20 individuals. Between 15' and 30' and 60' and 75'
the estimates were between 10 and 20 individuals. In those areas we took
an average with 10 on both edges, 15 in the midsections, and 42 for the
center average. This resulted in an extrapolation of 5,520 per minute,
331,200 per hour, and for 5 hours of the flow from 10 a. m. to 3 p.m.
a populaton of 1,656,000 which were moving at 20 to 25 mph.
The stark numbers in no way enable me to describe what it was like to
stand in the road and be surrounded with their orange fluttering filling
the air, to feel the wind of their passage and, even in my hearing empaired
state, to hear the passage of their wings!
We went back the very next day and observed no monarchs flowing down from
Capulin. When we arrived at Valle de Bravo there was a similar, but much
smaller population using the road under the aegis of heavily armed state
police, who enforced a slow crawl of the traffic through their ranks.
We rolled down our car windows and, sticking our arms out the window "flew
along" with the migration!
Carol Cullar, Executive Director
Rio Bravo Nature Center
Foundation, Inc.
Eagle Pass, TX
