426 K. C. PARKES 



from Wetmore, 1956). Six endemic genera of owls are currently 

 recognized from the New World. On the other hand, no fewer 

 than eight species, in six genera, are currently considered to be 

 conspecific with Old World owls ; among these is a panarctic species 

 with no races, the Snowy Owl [Nyctea scandiaca). Another species, 

 the Short-eared Owl {Asio flammeus), has a highly unusual dis- 

 tribution. The nominate race is found, without appreciable geo- 

 graphic variation, throughout Europe and northern and central 

 Asia, and in North America through about the northern half of the 

 United States. There is then a distributional gap, beyond which 

 the species reappears (as subspecies bogotensis) in the arid temperate 

 zone of the mountains and plateaus of the northern Andes. Again, 

 beyond a gap, appears the subspecies suinda, which ranges from 

 southern Peru and southern Bolivia to Tierra del Fuego. There are 

 isolated endemic subspecies on the Falkland Islands, the Hawaiian 

 Islands, the Galapagos Islands, Hispaniola, Puerto Rico, and 

 Ponape in the Carolines. Probably few living species of birds have 

 had so complex a distributional history. 



A good illustration of the value of the fossil record where it is 

 available to counteract misleading evidence based on modern 

 distribution is furnished by the family Gruidae, the cranes. On the 

 basis of the living forms only, one would probably characterize 

 this family as a rather recent immigrant to the New World, for 

 there are only two American species, one of which also occurs in 

 eastern Siberia and both of which belong to a widespread Old 

 World genus, and cranes have penetrated only as far south in the 

 New World as Cuba. However, the evidence of the living species is 

 misleading. Cranes of as many as three extinct genera are known 

 from the Eocene of Wyoming, and one Eocene fossil is tentatively 

 assigned to the living genus Grus. But lest it be thought that cranes 

 became extinct in North America in, perhaps, the late Tertiary, 

 with the two living species representing a rather recent second 

 invasion, it should be pointed out that fossils indistinguishable from 

 the living species occur as early as the Pliocene: the Whooping 

 Crane in the Upper Pliocene, and the Sandhill Crane in the Lower 

 Pliocene. 



Good examples of what were undoubtedly secondary New World 

 radiations from an early invading Old World stock are the cuckoos, 

 the pigeons, and the jays. The large and diverse Old World family 



