Patterns of distribution of swifts in the Andes of Ecuador

MARlN M.

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Abstract:

Trans-Anden elevational (above sea leve!) and vertica! (above ground) patterns of distribution of the resident swifts species in Ecuador were examined. The four types of limits for species distribution along an elevational gradient proposed by Terborgh (1971) and Terborgh and Weske (1975) were assessed as to their effects in swift distribution. 1) "Natura! terrninus of the environmenta! gradient" might affect only two species. 2) "Factors in the physical or biologica! surroundings that change parallel with the gradient" were possibi!ities for six of lO species. 3) "Competitive exclusion" was not found in the elevational gradient, but, is likely to operate in partitioning the vertical component. 4) "Vegetational ecotones" did not seem to affect the aeria! guild.