72 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I50 



Two geographic races of this wide-ranging bird are recognized at 

 present. The northern form Anhinga anhinga leucogaster (Vieillot) 

 of the southeastern United States, south throughout Central Amer- 

 ica, and of Cuba and the Isle of Pines, has the light band at the 

 tip of the tail narrow and averages smaller. 



Males (44 specimens), wing 316-347 (330), culmen from base 

 74.0-89.9 (81.8) mm. 



Females (28 specimens), wing 314-348 (327), culmen from base 

 70.5-85.0 (77.8) mm. 



The typical form Anhinga anhinga anhinga (Linnaeus), found 

 in northwestern South America from Colombia to western Ecuador, 

 and east of the Andes south to northern Argentina, has the light tail 

 tip definitely broader and averages larger. 



Males (14 specimens), wing 325-365 (341), culmen from base 

 84.7-98.8 (91.8) mm. 



Females (16 specimens), wing 312-361 (335), culmen from base 

 81.7-91.5 (86.3) mm. 



Intergradation between the two begins in Panama where the 

 birds are intermediate, but nearer leucogaster, and continues in 

 northern Colombia, where they are intermediate also but nearer 

 anhinga. 



The population from western Mexico south to Guatemala appears 

 to average slightly smaller than leucogaster from elsewhere and has 

 been named A. a. minima by van Rossem (Ann. Mag. Nat, Hist., 

 1939, p. 439) , with type locality Acaponeta, Nayarit. The suggested 

 color characters of the proposed form do not hold. The specimens 

 seen in the present study from the area concerned have been small, 

 but all have been immature birds (including the type) and these 

 usually are smaller than adults. The race is one of questionable 

 validity. 



Family FREGATIDAE : Frigatebirds ; Tijeretas de Mar 



The five species of this family are birds of the warmer seas around 

 the world. All agree in long, angular wings and deeply forked tail, 

 with the differences that separate them specifically found in size, 

 in combination with the location, or absence, of white markings. 

 One species is common along the coasts of Panama, but another may 

 be expected to come casually along the Pacific. 



