FAMILY LARID.E. GULLS AND TERNS. 



41 



SUB=FAMILY STERNIN/E. 

 Terns. 



upper mandible, nearly straight, not hooked or decid- 

 ediy rounded near tip; outer tail feathers, 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. 



Foreheud, white; l)ill, black; uiulerparts, white; back, 

 pearl gray; crown, black (adult in summer) ; back and crown, 

 mottled (immature). Stprnt/ tnitillarum. Least Tern. 



Sec \o. -IS. 



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



Head and uuderparts, black (adult). A patch of black behind the e^e; bacl< of head, 

 dusky; rest of head, white (immature). Uydrochelidon nigra surinamensis. Black Tern. 



See \o. 51. 



* 



Group 3. Wing, 8.50 to 9.50 inches long. 



Outer tail featlmrs, pure white. 

 Inner web of outer tail feather, gray. 



Sterna doui/alli. Roseate Tern. 



See \o. -17. 



Sterna for St eri. Forster's Tern. 

 See No. 4-1. 



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



Outer web of outer tail feather, darker tlian inner web; hack, jiearl gray; iireast, 

 wasiied with pearl gray; bill in adults, red, lipped witli black; lai'^ii-;, usually o\('r .70. 



Siernn hirnndo. Common Tern. Wilson's Tern. 



See No. 4."). 



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

 wbii>- ; hill in adiills, black, sli<;lit ly yellowish at tip. Strrna forstt-ri. Forster's Tern. 



See No. 44. 



Outer tail feather, entirely pure white; back, ix'arlgray; breast, whiti-, ofim lingiil 

 with faint rosi- color; hill, in adults, bbu'k with tiasal portiou, red. 



Sti-nm diimjnUi. Roseate Tern. 

 See No. 47. 



* For (ilrcctiotis for uicasurcment, nee pftge 9. 



