Butterfly count

A butterfly count is an event that is organized for the purpose of identifying and counting butterflies in a specific geographical area. Butterfly counts occur regularly in North America and Europe.

The counts are conducted by interested, mostly non-professional, residents of the area who maintain an interest in determining the numbers and species of butterflies in their locale. A butterfly count usually occurs at a specific time during the year and is sometimes coordinated to occur with other counts which may include a park, county, entire state or country. The results of the counts are usually shared with other interested parties including professional lepidopterists and researchers. The data gathered during a count can indicate population changes and health within a species.

Professional, universities, clubs, elementary and secondary schools, other educational providers, nature preserves, parks and amateur organizations can organize a count. The participants often receive training to help them identify the butterfly species. The North American Butterfly Association has organized over 400 counts in 2014.

There are several methods for counting butterflies currently in use, with the notable division being between restricted and open searches. Most counts are designed to count all butterflies observed in a locality.

Counts may be targeted at single species and, in some cases, butterflies are observed and counted as they move from one area to another. A heavily researched example of butterfly migration is the annual migration of monarch butterflies in North America. Some programs will tag butterflies to trace their migration routes, but these are migratory programs and not butterfly counts. Butterfly counts are sometimes done where there is a concentration (a roost) of a species of butterflies in an area. One example of this is the winter count of western monarch butterflies as they roost together at sites in California, northern Mexico and Arizona.

Frequently referred to as "Pollard Transects" or "Pollard Walks" in North America, a transect is a protocol designed to standardize the recording of butterfly observations, the initial format was outlined by Ernie Pollard in 1977. The transect protocol involves one observer walking a fixed path at a constant pace, multiple times in a season. Butterflies are counted when they are seen within a prescribed distance from the path, often 2.5 meters on either side of the path, and only when the butterflies are seen in front of, or above, the observer (i.e., no backtracking). A second person may work with the observer to identify and/or photograph insects spotted by the observer. Transects should not change from year to year and ideally should sample a variety of habitats.

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Wikipedia