28 Alexander G. Ruthven 



Nevada been settled by the Spaniards and their descendants for nearly four 

 hundred years, but they found there upon their arrival a larjii^e population 

 of Indians, living largely by agriculture, the remnants of which still exist 

 •on those southern slopes and in the three valleys of the north slope which 

 today show large areas of savanna. It is an absolute certainty that the 

 savannas on the north and west slopes have been caused entirely by defores- 

 tation and burning done by the Indians. I am also inclined to believe that 

 the southern slopes of the Sierras were at some time forested to a much 

 greater extent than at the present day and that their present barren con- 

 dition has been brought about largely by deforestation and burning. A 

 mountain savanna when once started, and burned over every year at the end 

 of the dry season, will spread very rapidly, for with each burning the sur- 

 rounding woodland is killed for distances varying with the character of the 

 imderbrush and the steepness of the slope, the fire often running up a steep 

 slope through the forest for miles before dying out. The Colombians as 

 Avell as the Indians invariably burn over the savannas every year, just before 

 the spring rains, to remove the hard, woody grass stems and to stimulate 

 the growth of tender fresh grass for their livestock. It is probable that the 

 original forest growth of the southern slopes was not dense owing to the 

 lesser amount of precipitation there, brought about by natural topographical 

 conditions, as elsewhere explained, and for this reason was the more readily 

 destroyed by fire. Once destroyed, its replacement was an impossibility, 

 owing not only to repeated burnings but to diminishing rainfall, due to the 

 absence of woodland. Probably the most striking confirmation of the 

 recent formation of savannas at the foot of the southern slopes, is the fact 

 that there is an entire absence of any reptilian or amphibian fauna peculiar 

 to natural savanna, all the forms taken on these savannas being the same as 

 those present in the surrounding and adjacent forest or scrub. 



General Character of the Faunas. Mannnalian and Aznan: Taken as 

 a whole, the fauna, especially the bird fauna, of the Sierra A^evada de 

 Santa Marta, is not an abundant one, as represented either by species or 

 individuals, when compared with that of many parts of the Colombian 

 Andes. The great group of fruit-eating tanagers, so abundant in all three 

 ranges of the Andes, is conspicuously absent here, but three species of 

 Tanagra being found from sea-level to timber-line. Buthraupis and Comp- 

 socoma are entirely absent, while Poecilothraupis and Ramphocelus are 

 represented by but a single species each. The other great fruit-eating 

 groups, the parrots, toucans and trogons, are also poorly represented from 

 the foothills upwards. Parrots are abundant in the lowlands of the west 

 and parts of the south side. In the mountains proper but four species of 

 parrots, two of trogons and three of toucans are found, wdiich is a mere 

 bagatelle as compared with the Andes, especially the parrots. This undoubt- 

 edly shows that the forest growth, which is very different from that even 

 of the eastern Andes, offers little in the way of fruits and berries. On the 

 other hand, insectivorous forms are more abundant, especially the Dendro- 

 colaptidse and Formicariida;. Hummingbirds are also poorly represented 

 everywhere, and present in small numbers, with the exception of a few 



