FAMILY LARID.E. GULLS AND TEItNS. 



41 



SUB=FAMILY STERNIN/E. 

 Terns. 



upper mandible, nearly straight, not hooked or decid° 

 cdly rounded near tip; outer tail leathers, usually longer 

 than middle feathers; toes, four; front toes, webbed; 

 hind toe, small, but well developed. 



Group 1. Wing, 5.50 to 7.50 inches long. 



Forehead, -svliite; hill, hhick; umlerparts, white; hack, 

 pearl gra.v ; crown, hlack (adult in summer) ; hack and crown, 

 mottled (immature). Sterna antillarum. Least Tern. 



See Xo. 48. 



* Group 2. Wing, 7.50 to 8.50 inches long. 



Head and underparts, hlack (adult). A patch of hlack hehind the ej-e ; l)ack of head, 

 dusky; rest of head, white (immature). Hydrochelidon nigra snrinamensis. Black Tern, 



See Xo. 51 . 



* Group 3. Wing, 8.50 to 9.50 inches long. 



Outer tail feathers, pure white. 

 Inuer wel) of outer tail feather, gray. 



Sterna dougalU. Roseate Tern. 



See No. 47. 



Sterna forsteri. Forster's Tern. 



See No. 44. 



* Group 4. Wing, 9.50 to 1 1 inches long. 



Outer web of outer tail feather, darker than inner web; hack, ptrl gray; hreast, 

 washed with pearl gray; hill in adults, red, tipped with black; tarsus, usually over .70. 



Sterna hirundo. Common Tern. Wilson's Tern. 



See No. 45. 



Inner web of outer tail feather, darker than outer web; back, pearl gray; breast, 

 white; bill in adults, black, slightly yellowish at tip. Sterna forsteri. Forster's Tern. 



See No. 44. 



Outer tail feather, entirely pure white; back, pearl gray; breast, white, often tinged 

 with faint rose color; bill, in adults, black with basal portion, red. 



Sterna dougalli. Roseate Tern. 

 See No. 47. 



* For directions for measurement, see page 9. 



