REPRODUCTIVE STRATEGIES IN ALPINE ADDERS, VIPERA-BERUS - THE BLACK FEMALES BEAR MORE OFTEN

Recent studies have demonstrated that melanistic adders are thermoregu latorily superior to cryptic (zig-zag) specimens, and that, because of this thermal superiority, they may result in faster growth rates and larger body sizes in comparison with the zig-zag individuals. A conseq uence of this size-advantage is that black females may have higher fec undity. Based on a five-year study by ''mark and recapture'' on an alp ine polymorphic adder population, we demonstrate that in this populati on the melanistic females were able to reproduce significantly more of ten than cryptic ones (differences significant at P = 0.015). The incr eased frequency of reproduction of black females possibly depended on the higher thermal efficiency of melanistic individuals (GIBSON & FALL S, 1979) permitting them to be active in the open during cold days in which zig-zag vipers are not active, and thus to spend more time forag ing, accumulating energy reserves for future reproduction.