NO. 2 AVIFAUNA OF PLEISTOCENE IN FLORIDA WETMORE 5 



in question. Progress in our knowledge of these matters lias been so 

 rapid that it may be confidently predicted that eventually all of our 

 existing species, except those of small size, will be identified in Pleis- 

 tocene deposits. As conditions are seldom favorable for preservation 

 of small bones of fragile texture, not much can be known of the 

 smaller birds as fossils, for their preservation in that state is highly 

 fortuitous. We may dream, however, of the discovery of ancient 

 caves, inhabited long ago by Pleistocene owls, with great accumula- 

 tions of bones of small birds from the pellets of these nocturnal 

 predators — caves that have been hermetically sealed for tens of thou- 

 sands of years that chance may bring to attention and so give us 

 unexpected information on a fascinating subject. 



As his studies in avian paleontology have progressed the writer has 

 become convinced that evolution of our existing birds so far as 

 differentiation of species is concerned has taken place principally in 

 the late Tertiary, and that variation since tliat time has been of slight 

 degree, confined apparently to minor dififerences (in color and dimen- 

 sion) such as are used in our modern studies to distinguish the less 

 definitely marked of geographic races or subspecies. As our informa- 

 tion increases it appears that some of the differences that we consider 

 today as of subspecific value were in existence in birds of the Pleisto- 

 cene, for example in the gray cranes and in the turkey vultures, and 

 liave persisted to the present without apparent change, a striking ex- 

 ample of stability in these groups. 



The diversity in the bird life of North America at the time of the 

 coming of the rigors of the Ice Age must have been truly remarkable 

 since it would seem to have included most of our modern forms to- 

 gether with a host of others now extinct that are slowly becoming 

 known from the fossil record. The entire period since the opening 

 of the Pleistocene has been one of extermination rather than of evolu- 

 tion, a process that continued steadily until men appeared as the most 

 active factor contributing to its progress. 



THE SEMINOLE AREA 

 The region surrounding the small settlement of Seminole, not far 

 from St. Petersburg, Pinellas County, Florida, has been designated as 

 the Seminole area (see pi. i). In 1924 Mr. Walter Wetmore Holmes 

 discovered here a scute from the glyptodon Chlmnythcrhim septcn- 

 tnonalc, and through continued search during the succeeding 5 years 

 unearthed numerous other fossil bones including among them many 

 remains of birds. It is the Holmes collection of fossil birds that 

 initiated the writer's present studies on the Pleistocene avifauna of 

 Florida. 



