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Dry Conditions Force Colonies to Split
Field Notes from Mexico from Dr. Bill Calvert

March 2, 2006



Listen to Dr. Calvert 

Found tag!
Tag number GAZ175 was found by yours truly. She was a medium-sized female, watering in a shallow stream crossing down from the Rosario Colony. I wonder where she is from.

Colonies Are Splitting
Two colonies have split. The massive Rosario Colony now has an upper part situated in the side of the Arroyo de los Conejos. The lower part is larger and remains centered within the area defined by the stairs and trails.The movement is a mystery in that the new colony is clearly above the established colony. Usually the movement is down slope. One possible explanation is that a large water source is available in the direction of the new colony on the Llano de los Conejos.

The Pelon Colony is also split, but in a traditional manner. A small colony is forming down the mountain from the original location. The original colony at Pelon has some of the most heavily butterfly-festooned oyamel firs that I have ever seen. Everyone agrees that the Pelon colony is the most beautiful probably because the forest is so beautiful. We commend the people of the Macheros ejido for taking such good care of their land.

As 'Dry as a Bone' So Colonies Must Move
The entire terrain is dried out this time of year because there is just no, there’s hardly any water available in the form of dew or rain. The Tuesday rain shower brief rain shower was a great exception. (It rained on us. But it was one of those kind of showers that didn’t even wet the ground.) Basically the entire mountainside is as dry as a bone and the butterflies are forced out of the colonies down to open sources of water to drink. So that’s why so much colony movement this time of year. They are leaving the colony and they’re going down, and they’re not going all the way back.

Watersheds Protected for Late-Season Needs
In both cases they are still within the Reserves (or at least the buffer areas of the Reserve, I’m not sure exactly where the boundaries are). In the areas that we have been investigating the watersheds are protected. And this is a very good thing because the butterflies are not only situated in the colonies that they form early in the year. They move down and they use the lower portions of these watersheds during the latter part of the year so it’s very important that the entire watershed be protected.

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