VENEZUELAN ORNITHOLOGY — FRIEDMANN AND SMITH 469 



gentle rise in the percentage of green trees, usually a thin veil of par- 

 tially opened buds, caused by local showers, subsurface water, or a 

 local concentration of nondeciduous trees. In the region below the 

 point of sharp change from the seasonally deciduous forest of the low- 

 lands to the subtropical montane forest of the coastal mountain range 

 the estimated percentage of trees in leaf nowhere attained 20 percent. 



70 



;oo V. 



D 



Figure 



106. — Average rainfall (bars), number of species of trees in flower (solid line), 

 percentage of trees in^leaf (dashMine) Jn study^area. 



This area (fig. 107) stands in sharp contrast with the northeastern 

 United States, where in spring the trees come into leaf with the grad- 

 ually increasing warmth. Moisture is available from melting snow 

 and from frozen interstitial water in the soil, and the rains, governed 

 for the most part by extensive "lows," cover wide areas, so that at 

 any given date the woods are at approximately the same stage of 

 development throughout the region. In our area, on the other hand, 

 temperature is presumably not a factor, as it fluctuates so little 

 throughout the year, and "spring" comes at the end of the dry season, 

 when the soil is extremely dry (at Cantaura, Anzodtegui, April 20, 



