DIRECTORY TO BIRDS OF EASTERN NORTH AMERICA. 55 



with several of its fellows, this general movement being 

 made suddenly in response to a cry given by some member 

 of the flock that evidently acts as a leader. 



f. Dusky-backed Terns. Haliplana. 

 Size, rather large; mantle and head, dusky or black; 

 bill, slender, and with feet, wholly black ;tail, deej^ly forked, 

 figs. 68, 69 : flight, much as in d ; tropical and subtropical in 

 distribution. Egg, single, lighter in color than in d. 



1. BRIDLED TERN, H. anaethetus. 14.00; form; 

 slender; above, rather pale brownish-slate becoming lighter, 

 nearly white, in Fig. 68. 



a collar on back 

 of neck and on 

 tail, the outer 

 feather of which 

 is white except- 

 ing at tip and all ^ 

 the others white 

 at base; three , _____ , ,^,„ 

 outer primaries '~~Z^-/P'^^^'-^-^^^ 

 have a j^ure I*^, C, f, 1. 1-6. 



white space on the middle of the inner web which narrows 

 to a point terminally ; top of head, brownish-black with a 

 well defined frontal lunette the horns of which extend back- 

 ward over and behind eye; beneath, pure white, fig 68. The 

 young have the white of the forehead more extended and 

 and the back is grayish more or less streaked with white. 

 Flight, swift and graceful, the wing-bfeats being long and 

 sweeping. Cries, rather shrill; ordinary note, "/w7//zVX", 

 often repeated ; the alarm note is a croak ; the signal for the 

 flock to dart downward when flying is a shrill, snarling note. 

 Tropical sea coasts in general ; breeds commonly on the Ba- 

 hamas in May in places rather apart from other Terns, nest- 

 ing under rocks ; appears on the Bahamas the last week in 

 April and disappears in autumn ; accidental in Florida. 



2, SOOTY TERX, H. fuliginosa. Differs from 1 in be- 

 ing larger. 16.00 ; not as slender ; darker above, uniform 



