Todd-Carriker : Birds of Santa Marta Region, Colombia. 81 



thraupis," and Hemithraupis. It is not probable that the absence of 

 these forms, and of others which could readily be named, is merely 

 accidental. If any conclusion may be drawn from such negative evi- 

 dence, it must be that many species have failed to reach the Santa 

 Marta region, or failed to maintain themselves there because of the 

 conditions which obtain, and that the fauna is in realitv semi-insular 

 and depauperate, despite its diversity in character. 



The inclusion of the lowlands of the Santa Marta region within the 

 limits of the Caribbean Fauna, as the latter is characterized by Dr. 

 Chapman in his recent work, is not open to criticism so far as its 

 arid and semi-arid parts are concerned. Whether there are sufficient 

 grounds for a formal subdivision of the Caribbean Fauna into an 

 eastern, or Venezuelan, and western, or Colombian, section, is an open 

 question, to the consideration of which the writer hopes to return at 

 some future time, with more data in hand. It is certain that the 

 Caribbean Fauna as it now stands is heterogeneous, and that in the 

 event of its subdivision it would be necessary to recognize the Santa 

 Marta region as a distinct and coordinate faunal area, partaking as it 

 does of the nature of both extremes as well as possessing marked char- 

 acteristics of its own. 



The Subtropical Zone. 



Character and Extent.- — Ascending above the Tropical we enter a 

 zone entirely different in its physical aspects as well as in its fauna 

 and flora. This has been called by Dr. Chapman the Subtropical or 

 " Cloud " Zone, the vernacular name from the circumstance that its 

 lower limit coincides with the level of the clouds. As already said, 

 this level is at an average elevation of about 4,500 feet (more in some 

 cases) except on the north slope of the main Sierra Nevada, where 

 it descends as low as 2,000 feet. The Subtropical is primarily a zone 

 of humid forest, and its life is accordingly much more uniform in 

 character (from a faunal standpoint) than the life of the Tropical. 

 Wherever there are areas of savanna or open shrubbery within the 

 limits normally occupied by this zone, the birds inhabiting such areas 

 will invariably be found to be species of either the Piedmont belt of 

 the Tropical Zone, which have ascended from below, or else those of 

 the Temperate Zone, which have followed their natural environment 

 downwards. This is well illustrated at San Sebastian, which is situ- 



