Left and centre: Scopoli's, right Cory's; from the publication
Robert Flood (FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch, South Africa) and Ricard Gutiérrez have published in the open-access journal Marine Ornithology on separating Scopoli's Calonectris borealis and Cory's C. diomedea Shearwaters from ther underwings.
The paper’s abstract follows:
“The genus Calonectris contains four species: Streaked Shearwater C. leucomelas (which breeds in the North Pacific mainly on islands off Korea, Japan, and Taiwan), Scopoli's Shearwater C. diomedea (which breeds mainly in the Mediterranean Sea), Cory's Shearwater C. borealis (which breeds mainly on islands in the Northeast Atlantic Ocean), and Cape Verde Shearwater C. edwardsii (which is an endemic breeder of the Cape Verde Islands). In this study, we were concerned with the field separation of the cryptic pair Scopoli's Shearwater and Cory's Shearwater, only briefly considering the more easily recognised Streaked Shearwater and Cape Verde Shearwater. Background information is summarised in Appendix 1, available on the website).”
John Cooper, ACAP Information Officer, 26 October 2021