52 



KEY TO GULLS (cont.) 



7 Mantle (see Fig. 11) dark gray; culmen length 20 mm or less; 



tarsus red, and very brightly so in fresh specimens. 18 



7' Mantle pale gray; culmen 31 mm or more; tarsus black or grayish. 19 



8 Wing length <230 mm. 20 

 8' Wing >230 mm. 9 



9 Upper wing surface with three bold triangles of more or less solid 

 color: outer primaries forming black triangle, inner primaries 

 and secondaries forming white triangle, wing coverts and back 



forming gray or brown triangle (Fig. 23c); tail slightly forked. 21 



9' Upper wing surface not displaying triangles of solid color. 10 



10 Wing mostly uniform gray above and below, except black leading edge 

 to outer primary; central tail feathers longer than outer tail 

 feathers; pink cast to underparts. ROSS 1 GULL, adult 



10' Not as above. 11 



11 Outer primaries with conspicuous white areas. 22 



11' Outer primaries uniformly dark, or with very small white areas at 

 tips; tail white with black band not extending to two outermost 

 tail feathers. FRANKLIN'S GULL, first year 



12 Wing length >275 mm; underside of wing grayish. 17 

 12' Wing <275 mm. 13 



13 Upper wing surface with brown or black bar at base of secondaries 



(Fig. 236). 14 



13' Upper wing surface without brown or black bar at base of secondaries. 



BONAPARTE'S GULL, adult 



