The article offers a comparison of presumed Elegant and Cabot's Tern hybrids' external characteristics with those of their presumed parental species. The very high proportion of hybridization of North American and European tern species is discussed wherein 44 percent have been reported to hybridize compared with the 10 percent of all bird species. A table shows the anatomical characteristics of 15 presumed Thalasseus (T.) elegans and T. acuflavida hybrids on Isla Rasa, Gulf of California, Mexico. The possible contribution of Cabot's and Elegant Tern on the hybrids' characteristics such as bill length, bill depth, and leg color are estimated.