•'THE D/STh'IJJl TW\ OF ULUD-LIFI-: IX COLOMlilA' 



4ST 



imu'li of it is <;i\('ii <i\('r lo _i,n*aziiii;' in- 

 stead (if agriculture ( duuhtlcss owiiiij to 

 transportation (lilllrult ics), suii'ar. cof- 

 fee, eacao. I'icc. and ti'o|Mcal I'l'uits 

 grow luxui'iantl V. 'The Mai^dalcna \'al- 

 Icv. Iiclwccn the ccnli'al and ca>tci'n 

 ran^U'cs, is somewhat l>i"oader and mucli 

 more arid except in its lower (norlli- 

 iM'n) reaches where it is ([uite the re- 

 \crse. 'idle exteiisixc le\(d re^'imi ea>t 

 (d' the easlei'ii I'aiiii'e is sinndai' to adja- 

 cent parts (>r N'enezuida and Ui'azil. 

 there heini:' Hanos noi'th of the (inavi- 

 are Kiver. and south of it the yreat 

 Amazonian forest. 



l^r. ('ha]»nnin points ont that all the 

 life of tropical South America was 

 probably alike prior to the rise of the 

 Andes Mountains and as late as the 

 latter half of the Tertiary period. If, 

 at that time, there were no mountains 

 to act as barriers to the moistnre-laden 

 winds and no differences in altitnde, 

 the sea of life that flowed through the 

 continuous forest must have been quite 

 uniform from the Atlantic to the Pa- 

 cific. Indeed, today, the faunas of the 

 tropical Pacific area and the great 

 Amazonian forest are very similar in 

 spite of the barrier separating them. 

 But with the rise of the mountains, 

 there came great differences in climatic 

 conditions and eventually five distinct 

 areas could be recognized. West of the 

 mountains was an area of great con- 

 densation, the moisture-laden winds 

 from the sea giving up most of their 

 vapor and causing vegetation of great 

 luxuriance to grow. Xorthward. along 

 the Caribbean Sea, was an area which, 

 entirely cut off by the mountains from 

 those breezes, then became arid. East 

 of the mountains, the northern Ori- 

 nocan part became arid while the south- 

 ern part received its moisture-laden 

 winds from the southeast and remained 

 extremely humid. The valleys of the 

 Cauca and ilagdalena Ijecame more or 

 less cut off from the other regions by 

 the mountain barriers and formed a 

 fifth area, part arid and j^art humid. 



Altitudinally the change was even 

 more striking. IJeginiung at sea level 

 and continuing up to an altitndi' of 

 fl'om l.'iOO lo (iIMM) feet, the t I'opieal 

 foi'esis and all their life contituieil to 

 luxuriate. Fi'oni the upper reaches of 

 the tropical belt to about !)()()() or D.IOO 

 feet, coiidiiious (dianged. The temper- 

 ature decreast'd and the "I'owin"' season 

 became shorter. Ti'opical forms either 

 had to adapt tlieins(d\-es to [he shorter, 

 cooler seasou oi' pei'ish, and so. as thev 

 were carrie(l upwai'd liv the I'ise of the 

 ]iiountains, many new forms or adap- 

 tations arose and a new fauna was es- 

 tahlished wduch Dr. Chapman ha.- 

 called the Subtropical Zone fauna. As 

 the mountains rose higher and higher, 

 a third belt was correspondingly formed 

 so that today between 9000 'to ^riOO 

 and 11,()(»0 to 13,000 feet, we have the 

 Tem])erate Zone. Conditions here are 

 not unlike those of temperate Xorth 

 America, or South America in Chile 

 and Argentina. In fact, so like were 

 the conditions of southern Chile to 

 those of the mountains of Colombia, 

 Ecuador, and Peru above 9500 feet, 

 that many southern forms of this region 

 extended their ranges northward to oc- 

 cupy the territory newly formed. Thus 

 while the l)irds of the Subtropical Zone, 

 between 4500 and 9000 feet, are today 

 most closely related to the tropical 

 forms below them, the birds of the 

 Temperate Zone are most closely re- 

 lated to the seacoast forms of southern 

 Chile. 



At an altitude of from 11,000 to 

 13,000 feet, tree growth stops. The 

 season is too short for any tree to thrive 

 and there is an area of sedges, her1)a- 

 ceous plants, and curious woollv peren- 

 nials. This is the region called Paramo 

 and extends up to snow line at about 

 15,000 feet. It is a land of fog and 

 sleet during the l)leak months of its 

 winter, and even during its short sum- 

 mer clouds roll up from the forests l)e- 

 low to obscure the landscape part of the 

 dav. 



