Todd-Carriker : Birds of Santa Marta Region, Colombia. 59 



for the ordinary collector who hopes to achieve any large success or 

 cover any extensive area. 



The Tropical Zone is the only zone in the Santa Marta region which 

 is continuous with the same faunal area in the rest of Colombia, the 

 upper zones all being isolated from the corresponding belts in the 

 Andes by the interposition of the Tropical. The Tropical, being thus 

 more accessible than the upper zones, has received by far the largest 

 proportion of the total life of the region. The following table com- 

 pares the number and relative percentages of the constituent elements 

 of the resident fauna of the Santa Marta region with that of the 

 Andes as a whole, species alone being considered. 



Zone. Santa Marta Region. 



No. of 

 Species. Percentage. 



Tropical 337 76.4 



Subtropical 75 17.0 



Temperate 22 5.0 



Paramo 7 1.6 



The falling off in the number of species with the progressive in- 

 crease of altitude is thus seen to be more abrupt than in the Andes, 

 and gives an insular character to the fauna of the Santa Marta region 

 which we shall see hereafter is borne out in other respects. 



The Tropical Zone. 

 Character and Extent. — The Tropical Zone of the Santa Marta 

 region not only occupies a larger area than do the remaining zones 

 combined, but also supports by far the most birds, both species and 

 individuals, as well as the gr;eatest variety. It comprises in general 

 all that part of the region lying between sea-level and the lower edge 

 of the ordinary cloud strata. On the San Lorenzo and its connecting 

 ridge, as. well as on the southern spur of the Sierra Nevada, this line 

 falls at between 4,000 and 4,500 feet, but on the north slope of the main 

 Sierra Nevada, facing the Caribbean Sea, it drops down to 2,000 feet 

 or even lower. As a result of conditions already explained there is 

 here a heavy humid forest extending right do^yn to the seacoast, and a 

 consequent lowering and very confusing overlapping of the life-zones. 



