Field Separation of Cory's Calonectris borealis and Scopoli's C. diomedea Shearwaters by Underwing Pattern

Authors

Robert L. Flood, University of Cape TownFollow
Ricard Gutiérrez

Abstract

Field separation of Cory’s Calonectris borealis and Scopoli’s C. diomedea shearwaters is notoriously difficult. Past, provisional research found that the most reliable method of separation is by underwing pattern. Here, we present a comprehensive study of the underwing patterns of both species from colonies and other locations in the eastern North Atlantic Ocean (Cory’s Shearwater) and Mediterranean Sea (Scopoli’s Shearwater). Data were derived from museum specimens, typed bycatch victims, and photographs of birds at colony, inshore by colony, and offshore in the Mediterranean. Results demonstrate that the large majority of Cory’s/Scopoli’s shearwaters are separable in the field, though overlapping features of the remainder are problematic. Improvements to the criteria for field separation will enhance studies of breeding limits, regional migration, and limits and variation in range, which, in turn, will highlight conservation needs of the two species.

DOI

http://doi.org/10.5038/2074-1235.49.2.1438

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Recommended Citation

Flood, Robert L. and Gutiérrez, Ricard (2021) "Field Separation of Cory's Calonectris borealis and Scopoli's C. diomedea Shearwaters by Underwing Pattern," Marine Ornithology: Vol. 49 : Iss. 2 , Article 22.
http://doi.org/10.5038/2074-1235.49.2.1438
Available at: https://digitalcommons.usf.edu/marine_ornithology/vol49/iss2/22