THE GULF OF MEXICO ECOSYSTEM: A COASTAL AND MARINE ATLAS
containing marine or estuarine habitats within the 15-mile-diameter count circle. Land cover data were used for the habitat-based selection process from the coastal change and analysis program produced by NOAA. Only count circles that were active for at least 7 out of the past 10 years (2001-2010) were used to compile these data. The mean number of loons observed per party hour for active survey years was then calculated and used to represent the number of common loons present in each circle. Party hours were used to standardize the counts by effort. A party hour equals one group of observers in the field for one hour. Data Quality Data quality for this map is fair in U.S. waters. There are 64 CBC circles along the Gulf Coast that intersect marine and estuarine habitats, but CBCs are typically, though not always, land-based. Therefore,
a complete count of all birds present within count circles is not likely. Few or no relevant CBCs exist for Mexico and Cuba. Synthesis and Conclusions Common loons are migratory water birds inhabiting the freshwater lakes of Alaska, Canada and the northern U.S. in the summer. In the fall, common loons from the Great Lakes region migrate to Gulf wintering waters, where they remain until spring. Common loon populations are stable, and the International Union for Conservation of Nature classifies common loon as a species of Least Concern. Long-term research and monitoring are essential to assess the effects of the DWH oil disaster on this long-lived species and inform restoration strategies.
Text Citations Cornell University. (2011, January 27). Common loon. Retrieved from http://www.allaboutbirds.org/guide/ Common_Loon/lifehistory Evers, D. C. (2004). Status assessment and conservation plan for the common loon (Gavia immer) in North America. Hadley, MA: U.S. Fish and Wildlife Service. Evers, D. C., Paruk, J. D., Mcintyre, J. W., & Barr, J.F. (2010). Common loon (Gavia immer). Retrieved from the Birds of North America Online database: http://bna.birds.cornell.edu.bnaproxy.birds.cornell.edu/bna/ species/313/articles/foodhabits U.S. Fish and Wildlife Service (USFWS). (2011, January 31). Digest of federal resource laws of interest to the U.S. Fish and Wildlife Service: Migratory Bird Treaty Act of 1918. Retrieved from http://www.fws.gov/ laws/lawsdigest/migtrea.html Map Data Sources National Audubon Society. (2010). The Christmas bird count historical results. Retrieved May 28, 2012, from http://www.christmasbirdcount.org Ridgely, R. S., Allnutt, T. F., Brooks, T., McNicol, D. K., Mehlman, D. W., Young, B. E., & Zook, J. R. (2007). Digital distribution maps of the birds of the western hemisphere, version 3.0. Arlington, VA: NatureServe.
MAP 25 (next page). COMMON LOON
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