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Volume 2010 (2010), Article ID 689301, 6 pages
Research Article

Citizen Science Observations of Monarch Butterfly Overwintering in the Southern United States

1Journey North, 6234 Mt. Philo Road, Charlotte, VT 05445, USA
2Port Lavaca, Calhoun County, TX 77979, USA
3D. B. Warnell School of Forestry and Natural Resources, The University of Georgia, Athens, GA 30602, USA
4Odum School of Ecology, The University of Georgia, Athens, GA 30602, USA

Received 3 May 2010; Revised 14 July 2010; Accepted 26 August 2010

Academic Editor: Michael Rust

Copyright © 2010 Elizabeth Howard et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Members of the public have long had a fascination with the monarch butterfly, Danaus plexippus, because of its amazing long-distance migration to overwintering sites in central Mexico, and many participate in online citizen-science programs where they report observations of its life history in North America. Here, we examine a little-studied aspect of monarch biology, the degree of overwintering in the southern United States. We compiled 9 years of sightings of overwintering monarchs in the southern United States that were reported to Journey North, a web-based citizen science program, to map the distribution of areas where monarchs are capable of surviving during the winter (i.e., in January and February), differentiating between adult sightings and sightings of breeding activity. We also statistically compared the latitudes of adult and breeding sightings, examined differences across years in latitude of sightings, and quantified the number of monarchs reported with each sighting. Of all 254 sightings, 80% came from Florida and Texas, with the remainder coming from South Carolina, Louisiana, Georgia, Alabama, Mississippi, North Carolina, and even one in Virginia. This distribution was generally consistent with the winter range predicted by prior investigators based on climatic conditions of this region. Sightings of adults were on average from higher latitudes than reports of breeding activity and there was significant variation across years in the average latitude of all sightings. The majority of sightings (94.2%) were of fewer than 10 adult monarchs per location, and there were no reports of clustering behavior that is typical of monarch overwintering in California and Mexico. The results of this investigation broaden our collective understanding of this stage of the monarch life cycle and, more generally, highlight the value of citizen science programs in advancing science.