NATURAL AREAS AND REGIONS 



609 



snow has been recorded in the i^igh 

 mountains. Tree-line is about 10,000 ft. 



S. Geographic and faiinal communities 



Costa Rica is a naturalist's paradise. 

 The varied topography and climate, 

 combined with favorable geographic 

 position, given it the most varied fauna 

 and flora, for so tiny an area, in the New 

 World. The continent has narrowed 

 down to sixty miles, and in this space 

 occurs an unparalleled diversity of 

 conditions. Its present fauna and flora 

 has been derived both from the north 

 and the south, and in past geological 

 periods the mountains have been an 

 island, on which peculiar and distinct 

 types have evolved. In birds at least 

 one peculiar family, numerous endemic 

 genera and species, give the Costa 

 Rican highlands rank as a distinct 

 faunal area. The very diversity of 

 conditions and origins, however, makes 

 the delimitation of life zones or ecologi- 

 cal associations particularly difficult and 

 complicated, and unfortunately any 

 detailed knowledge of local distribution 

 is entirely lacking. The great rarity 

 of many endemic species, some of general 

 distribution, and others confined to a 

 single mountain peak, affords still 

 further food for speculation. There is, 

 here, a fascinating field in the study of 

 geographic distribution, but only the 

 most generalized account can be given. 



Luxuriant tropical rain forest. The 

 Caribbean slope is the easiest to de- 

 scribe. It is covered with a dense 

 tropical rain forest, with an exceedingly 

 humid and unhealthy climate. It is 

 exactly the same as the Caribbean slope 

 of Nicaragua, described in the preceding 

 article. It has a typically rich and 

 varied fauna, all the conspicuous and 

 prevailing neotropical types occurring. 

 There are no less than 400 species of 

 birds recorded. The flora is little 

 known, but the trees are of great size, 

 and the undergrowth of creepers and 

 lianas makes progress difl^cult, without 

 cutting at every step. At the lowest 

 levels, especially near the rivers, jungles 



of palm catch the traveller's eye. (For 

 species, see under Nicaragua.) 



Arid deciduous forest. On the Pacific 

 side of the coimtry, the difference in 

 rainfall causes a difference in ecological 

 condition, and slight differences in the 

 fauna. The northwestern past, includ- 

 ing the Nicoya peninsula is a region by 

 itself, and is exactly the same as the 

 Pacific slope of Nicaragua (which see). 

 It is the extreme southern limit of a 

 fauna which contains such conspicuous 

 forms as the white-winged dove, a 

 cactus wren, a rock wren, several orioles 

 and a long-tailed crested jay (Calocitta). 

 As in Nicaragua an extensive Indian 

 civilization existed at the time of the 

 Spanish Conquest, and much of the 

 original gallery forest has disappeared 

 and is replaced by grassy savanna. 

 Further south the Pacific slope is covered 

 with a dense gallery forest, the fauna 

 of which, at least, is not so distinctly 

 different from the tropical fauna of the 

 Caribbean slope. In extreme south- 

 western Costa Rica from the Terraba 

 Valley and the Golfo Dulce southward, 

 the heavy gallery forest is again varied 

 by considerable tracts of savanna. 

 Ecologically there would seem to be 

 little or no difference, but the fauna 

 is quite distinct. Numerous endemic 

 species of birds, such as a black and 

 yellow mannakin (Manacus aurantia- 

 cus), a snowy cotinga (Carpodectes 

 antoniae), and a hummingbird {Agyrlria 

 boucardi), are found only here and in the 

 adjacent parts of western Panama. 

 The causes, which have evolved this 

 peculiar fauna, are not understood. 



Passing now from the purely tropical 

 zone to higher altitudes, a marked 

 change takes place, when we enter the 

 subtropical or upper tropical zone at 

 about 3500 to 4000 ft. There are two 

 distinct ecological divisions. The lower 

 plateau region, while originallj- forested, 

 is the most settled portion of the coun- 

 try, and has long since been cleared in 

 large part, and used for agriculture and 

 pasture. Such is the country around 

 Cartago and San Jose. There are 



