OVER THE ANDES TO BOGOTA 



361 



Photograph by Frank M. Chapman 

 FERRYING ACROSS THE CAUCA RIVER IN THE SHADOW OF CEIBA TREES 



Dust is here unknown, and I was im- 

 pressed by the cleanness of the foliage, 

 every leaf of which received a daily 

 shower. Nor did a knowledge of the fact 

 that these rain-soaked, almost impene- 

 trable, forests are inhabited by many 

 species of birds found in no other part 

 of the world detract from the interest 

 with which Louis Agassiz Fuertes, the 

 artist of the expedition, and I observed 

 them. 



In March, 191 1, when I visited this 

 part of Colombia, the railroad which now 

 reaches Cali was not completed beyond 

 Caldas, 2,500 feet above, and about five 

 hours from Buenaventura. 



Caldas lies in a basin-shaped valley, the 

 western rim of which, throwing what 

 is technically known as a "rain-shadow," 

 robs the immediately surrounding country 

 of the precipitation which so strongly 

 characterizes the Pacific slope of the 

 Western Andes in Colombia. As a result 

 the forests through which we had just 

 passed, and which crown the mountains 

 above us, are here replaced by grass- 

 covered hills with scattered cacti and 

 acacias, representing the flora of an arid 

 region. 



This was the first of many instances 

 where personal observation was found to 

 be absolutely essential to a proper inter- 

 pretation of faunal problems. It would 



be out of place to enlarge upon this 

 theme here, but I cannot leave it without 

 emphasizing the importance of field-work 

 in zoogeography, and the futility of at- 

 tempting to determine the boundaries of 

 faunal areas and the laws governing the 

 distribution of life merely on the basis 

 of a laboratory study of specimens. 



BIRDS RESTRICTED TO CEEAREY DEFINED 

 ZONES 



The irresistible combination of a re- 

 ligious fiesta and a wholly secular circus 

 so delayed the assembling, packing, and 

 saddling of our impressive array of mules 

 that we left Caldas the following morning 

 at too late an hour to reach Cali the same 

 day. The night therefore was passed at 

 Rancho El Tigre. We were now, how- 

 ever, in no haste. The back of a mule 

 affords excellent opportunities for recon- 

 naissance. The pack animals set the pace 

 of three miles an hour and rarely did we 

 care to increase it. Barometer in hand 

 we observed the changes in altitude and 

 noted their effects on the distribution of 

 life. 



As we became familiar with the birds 

 and learned to recognize them at sight and 

 by voice, we could predict with surpris- 

 ing accuracy when certain species would 

 appear and when they would in turn be 

 replaced by others. In spite of their mo- 



