NATURALIST'S GUIDE TO THE AMERICAS 



leras, the rainfall is distributed in two 

 wet seasons and its amount decreases 

 until portions of the Cauca and upper 

 Magdalena valleys become decidedly 

 arid. 



While generally the precipitation 

 increases as the mountains are ascended, 

 this rule is greatly modified locally 

 according to exposure to moi^ture- 

 bringing winds. Thus the plant-life 

 indicative of increased rainfall may 

 obviously be seen to increase upon the 

 western slope of the Central Cordillera 

 when an elevation is attained that over- 

 tops the opposing crest of the Western 

 Cordillera. Conversely upon the nor- 

 mally humid slopes of both the western 

 slope of the Western Cordillera and the 

 eastern slope of the Eastern Cordil- 

 lera occur pocket-like arid valleys 

 caused by the interception of the winds 

 by higher outlying spurs or ridges. At 

 higher levels the rainfall tends to be- 

 come more constant throughout the 

 year and to occur in lighter individual 

 showers, although the seasons are still 

 evident, and with a time of occurence 

 which may be much altered by local 

 topographic conditions. 



III. NATURAL REGIONS 



Since the wild life of Colombia is so 

 little changed from its primitive state 

 and since no areas whatever have been 

 set apart as preserves, it seems best to 

 modify somewhat the plan of present- 

 ment used in this volume for the several 

 states of the United States of North 

 America. We shall consider the differ- 

 ent natural regions of life, resultant 

 from topography and climate, and give 

 for each region one or more stations 

 from which it may be studied. In few 

 parts of Colombia and for few groups of 

 plants or animals is the flora or fauna 

 adequately known, so that possibilities 

 of valuable scientific exploration lie 

 within the reach of any who have op- 

 portunity to visit this land. 



The localities mentioned will be 

 assigned to their political department, 

 so as to facilitate finding upon standard 

 maps. There are few railroads in 



Colombia and none that serve to bind 

 together the entire country. Northern 

 Colombia, Antioquia, Tolima and the 

 Bogota section (Cundinamarca) are 

 interconnected by steamboat travel 

 on the Rio Magdalena, with a series 

 of subsidiary railroad lines. Steam- 

 boats from Cartagena also ply on the 

 Atrato and lower Sinu. The Cauca 

 Valley and southward should be reached 

 from the Canal Zone by steamer to 

 Buenaventura, connecting with a rail- 

 Tosujd to Cali. Another approach to 

 Colombia is by steamboat from Ciudad 

 Bolivar on the Orinoco in Venezuela 

 up the Rio Meta an approach which 

 only reaches the eastern "Llanos." 

 Also Cucuta, with railroad and steam- 

 boat connection to Lake Marocaibo in 

 Venezuela, is with difficulty reached 

 from the rest of Colombia. Roads for 

 wheeled vehicles scarcely exist beyond 

 the vicinity of the largest cities, so 

 that much of one's journey into and 

 across Colombia will be over primitive 

 trails, with mules or horses for riding 

 and for pack-loads. While readily trav- 

 ersed in the dry season, most trails 

 become difficult by reason of sloughs and 

 mud-holes in the rainy season. So far 

 as is consistent with the purpose of 

 one's journey one should plan a trip 

 across lowland trails for the dry season. 

 The mountain trails are apt to be none 

 too good at any season, but the months 

 of December to February and June 

 to August are usually the best for 

 travel. 



In this discussion we shall consider 

 first the areas of lowland and secondly 

 the mountain regions. All the lowland 

 regions of Colombia, except where arid 

 or, as at Popay^n, where, although 

 between the cordilleras, one is above the 

 truly lowland zone of life, are dangerous 

 to health by reason of malaria and other 

 tropical diseases. The upland mountain 

 zones are invigorating and healthful. 



A. Rain-forest 



The lowlands of Colombia are covered 

 with evergreen forests wherever rainfall 

 is sufficient in quantity and occurs 



