Todd-Carriker: Birds of Santa Mart a Region, Colombia. 75 



Helcodvtcs curvirostris Ramphocchis dimidiatus dimidia- 



Cyanocorax affinis affiuis tits 



Icterus mesomelas carrikeri Oryzoborus funereus 



Cacicus vitellinus 



Although it is a fact that the north coast region of humid forest 

 is apparently better adapted to these and other forms of similar tastes 

 than is the region east of the Cienaga Grande, we find that a consid- 

 erable percentage of such forms apparently do not enter it, being 

 confined to the latter region. Even making due allowance for the 

 possibility of certain species having been overlooked in one region or 

 the other, the discrepancy is striking, and in our opinion signifies that 

 these forms of the Humid Tropical must have entered this region 

 from the south, since not all of them have been able to complete their 

 distribution by passing the intervening semi-arid strip and occupying 

 the area of suitable habitat on the north coast. Turning now to Dr. 

 Chapman's list of Tropical Zone species which enter the Humid Cauca- 

 Magdalena Fauna from the east, we find that of seventy-six species 

 which he gives no less than fifty-six reach the Santa Marta region 

 either unchanged or as slightly modified forms. On the other hand, 

 of the fifty-nine species which he gives as entering the Humid Cauca- 

 Magdalena Fauna from the west, only five are known from the Santa 

 Marta region. This in itself is a striking confirmation of the theory 

 that the tide of Tropical Zone life which flowed into this region came 

 originally from the east, around the head of the Eastern Andes. Un- 

 fortunately our knowledge of this latter region is exceedingly scanty, 

 as Dr. Chapman remarks. 15 Sievers, however, reports that the forest 

 in the Sierra Perija and Sierra Negra (local names for parts of the 

 Eastern Andes opposite the Santa Marta region) generally begins at 

 about 1,200 to 1,400 meters (4,000-4,600 feet), although at Manaure 

 it is down to 1,100 meters (3,600 feet). At this height woods appear 

 everywhere on the whole range, forming a dark green crown as seen 

 from a distance. Between 1,600 and 2,500 meters (5,250-8,200 feet) 

 these woods are very dense (i.e., they are Subtropical Zone). We 



13 This is largely owing to the circumstance that it is inhabited by the 

 Motilone Indians, a savage tribe who permit no intruders into their domain, 

 and whom not even the Colombian Government has been able to subdue. The 

 region has been recently entered, however, from the Venezuelan side (com- 

 pare De Booy, Geographical Review, 1918, pp. 385 et seq.). 



