How Are Monarch Colonies Measured? The Scientists' Methods A "colony" is defined as an area of trees occupied by monarchs. The goal is to measure the overall area each colony covers. The area of all known colonies is then added for a grand total. The trees in a colony are often called “butterfly trees.” The scientists mark the butterfly trees around the perimeter of the colony with flagging tape. Then they measure the distance between the marked trees. They record the time and date they took measurements at each colony. Later they use special mapping software to compute the surface area of each colony. The colony's size is given in hectares. (One hectare equals 2.47 acres, about the size of 2.5 football fields.) The scientists do all of their measurements in December or January, as close together as possible. They travel to the places monarchs are known to form colonies historically, both inside and outside of the monarch Reserve. At each site, they must determine if and where colonies have formed. Mexican Scientist Eduardo Rendon This year’s work was led by Mexican scientists Carlos Galindo and Eduardo Rendon of WWF-Mexico and colleagues at the Reserva de la Biosphera Mariposa Monarca (REBMM). Mexican biologist Eligio Garcia marks the trees around the perimeter of the colony. Then he measures the distance between the trees. (2000 photos) Some Definitions: colony: An area of trees occupied by monarchs. hectare: One hectare equals 2.47 acres. population: A group of individuals that are all of the same species, but the individuals live in an area that is separate and isolated from others of the same species. reserve: Short name for "Monarch Butterfly Biopshere Reserve," the formal name of the land Mexico protects for overwintering monarchs. In Spanish, "Reserva de la Biosphera Mariposa Monarca (REBMM). Copyright 2002-2006 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form