﻿416 PROCEEDINGS OF THE NATIONAL MUSEUM vol. lOO 



It is often reduced locally to scrub, at times with bare patches, particu- 

 larly where the surface soil is altered by the occurrence of pebbly beds. 

 In the vicinity of water the dominant trees attain greater size, but the 

 general appearance of the forest shows little change. Approximately 

 90 percent of the trees composing this forest are deciduous, being in 

 general leafless throughout the dry season, although many blossom 

 during that time. The forest floor is bare, with the exception of 

 local areas covered with maya (Bromalia sp.). 



Vines are not abundant, arboreal epiphytes are rare, cacti are 

 typically confined to scattered individuals or small stands, palms and 

 heliconias are absent. 



Some of the trees collected as typical of this forest have been 

 identified as follows: 



Cochlospermum vitifolium Pithecelobium sp. 



Humboldtiella arborea Gyrocarpus americanus 



Machaeriurn grandifolium Ceiba pentandra 



Platymiscium pinnatum Guazuma ulmifolia 



Myrospermum frutescens Senegalia glomerosa 



Capparis odoraiissima Prosopis jidiflora 



Erythrina velutina Tabebuia chrysantha 



Some characteristic birds of the deciduous seasonal forest are: 



Crypturellus noctivagus erythropus Pulsatrix perspicillata perspicillata 



Buteo magnirostris magnirostris Nyctidromus albicollis albicollis 



Buteo nitidus nitidus Nyctibius griseus griseus 



Hypomorphnus urubitinga urubitinga Lepidocolaptes souleyetii littoralis 



Geranospiza caerulescens Myiarchus tyrannulus tyranmdus 



Leptoptila verreauxi verreauxi Tolmomyias fiaviventris collingwoodi 



Amazona ochrocephala ochrocephala Tardus leucomelas albiventer 



For obvious reasons, "edge" habitats are difficult to describe. 

 However, in the present instance the edge formed where for one reason 

 or another the deciduous seasonal forest isbrokenby openings of greater 

 or lesser extent presents a habitat to an important group of birds 

 rarely to be found in the woods themselves, or on the open savanna. 

 Apparently about one-third of the vegetation of the Sacacual-Las 

 Piedras formation may be considered as deciduous seasonal forest edge. 



There exists no extensive savanna edge, because the expanse of 

 savanna is rarely broken by patches of woods and because that zone 

 is generally set off physically from the surrounding countryside by 

 the abrupt chffs of the mesa scarp. The lowland seasonal forest 

 intrusion into the area is so limited that it is pointless to attempt to 

 distinguish an edge habitat. 



The deciduous seasonal forest edge presents itself typically as small 

 semiopen clearings covered with grass or shrubby carcanapire (So- 

 lanum verbascifolium) and bearing trees characteristic of this habitat. 

 The following trees, collected as typical of this habitat, have been 

 identified : 



