ERYTHRISTIC EGGS IN THE COMMON TERN

Erythrism, an abnormally reddish color, is known in the eggs of a few Laridae and Stercorariidae. It apparently results from the absence of one of the normal pigments and possibly an overdose of another. Erythr ism in eggs of the Common Tern (Sterna hirundo) is exceedingly rare. D ata from the long-term study of the large tern colony on Great Gull Is land, New York, provide accurate information about relative frequency of the phenomenon and demonstrate its continuity in two females with c hanging mates.