Field Notes from Mexico
from Dr. Bill Calvert

March 10, 2005
Never was the importance of shelter illustrated so dramatically than it was at the Chincua sanctuary yesterday, March the 8th. A number of us teachers, nature lovers from New York, Texas, Michigan, and North Carolina walked the 3 kilometers from the Rincon de los Lobos to the Chincua Colony located at the headwaters of the Zapatero Canyon.

Two thirds of the way, past the Molonera Alta and past the great Mirador with the 15” think maradrones, we encountered remnants of the old mid-Feb colony. High altitude westerly winds were blowing dry, cool air at nearly gale force. Trees were blown, branches shook, and butterflies lost their grip and were strew about the ground. Unfortunately for some of them, they were blown onto the main trail to the colony.

It was relatively easy for us pedestrians to pick our way amongst the fallen butterflies. But the horse carrying passengers to and from the colony didn’t bother. Some butterflies were crushed. Those that weren’t were exposed to increased risk of predation at night by the black earned mouse, and increased possibility of freezing if cold weather impacted the area. But the majority of the colony had moved down into the shallow headwaters of the Zapatero Canyon where they were protected from the high velocity winds.

Indeed, amongst the trees holding the clustered butterflies, we hardly felt any wind at all. A scant 300-400 meters to the west, we could hear the wind slamming into the trees growing near the ridgeline. The monarchs of Chincua are clearly smart, having chosen a location sheltered from the high velocity westerly winds.