Systematics

Named dougallii by Montagu in 1813 after a Dr. McDougall who reportedly obtained the type specimen from Cumbrey Is., Scotland. Other published names include rosea, douglasi, and even paradisaea, a name preempted by the Arctic Tern (Marples and Marples 1934).

Five subspecies named; not necessarily valid (see Gochfeld and Burger 1996). Races differentiated by wing length, bill length, and bill color.

S. d. dougallii (Europe, North Atlantic, and Caribbean): Variation in size and bill color nearly as great as that among other named subspecies. Wing length averages 228 mm in Caribbean to 232 mm in Northeast; mass 100 g in Caribbean versus 112 g in Northeast (see Appendix 3).

S. d. korustes (India and Sri Lanka to Burma): Distinctively small wing (212–224 mm) and back darker gray than on dougallii .

S. d. gracilis (n. and w. Australia to Indonesia): Short wing (208–230 mm) and relatively long culmen.

S. d. arideensis (Seychelles) and S. d. bangsi (New Guinea and e. Australia to Philippines): Smaller and questionably separable from each other. Bill redder in both races than in any other subspecies, and fully red when breeding, but may have black tip similar to that of Caribbean population of dougallii . Vaurie (1965) lumped arideensis under bangsi, but the range of gracilis partly separates these forms.

Enigmatic. Unique among the very similar-appearing, medium-sized terns in genus Sterna, because of downy chick characteristics and adult behavioral traits (Gochfeld and Burger 1996). Chick with spiky down more closely resembles Sandwich Tern than Common or Arctic terns. Some parental behaviors resemble those of crested terns (Thalasseus). Biochemical studies of relationships within Sterna lacking.

Hybridization

Roseate x Common tern mixed pairs and hybrids reported in Europe and all major North American colonies (Marples and Marples 1934, Hays 1975, Zingo et al. 1994). Recognizable intergrades constitute <0.2% of northeastern breeding birds, but occur disproportionately in small or peripheral colonies (ICTN). F1 crosses and backcrosses with either parental species have been documented to raise young to fledging (Hays 1975, Zingo et al. 1994, ICTN); 1 such backcross mated with a Common Tern at age 19 and raised young (ICTN). Two pairs at Great Gull I. involved F1 crosses, suggesting preference of hybrids for other hybrids (Hays 1975). In 1980 the only breeding New Jersey Roseate Tern was paired with a Common Tern (JB). Has also hybridized with Arctic Tern in Canada (Whittam in press) and probably in United Kingdom (Ewins et al. 1987).