Zonal Distribution of Vertebrates in a Mexican Cloud Forest

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Abstract
A very useful method of analysis in the study of faunal origin is based on the relationship of patterns of animal distribution to that of major vegetation types. Application of this method in a zonal analysis of cloud forest at its its northern latitudinal limit in eastern Mexico yielded the following observations: 1. Presence of a small but distinctive forest habitat, humid at all seasons, with a mild mean annual temperature of slight seasonal variation. 2. A unique indigenous floral assemblage including genera with both temperate and tropical centers of distribution, many of these found in Middle America only in the cloud forest. 3. A vertebrate fauna derived almost entirely from that of adjacent forest habitats, lacking most of the indigenous forms typical of cloud forest further south in Mexico and Middle America. The contrast between a rich indigenous cloud forest flora, actually richer than many similar areas further south, and a locally derived fauna lacking such distinctive elements suggests that the area has not been in recent contact with similar forests to the south. Possibly climatic change in this interval depleted the vertebrate fauna far more than the associated flora and left the habitat open to occupation by those animals occupying adjacent vegetations zones.