Cohort affects growth of males but not females in alpine ibex (Capra ibex ibex)

We studied long-term cohort effects on chest girth and horn length in a rec ently established population of alpine ibex (Capra ibex ibex). Environmenta l conditions of the year of birth affected chest girth and first-annual inc rement of horns of males but did not affect chest girth and horns of female s. Females compensated for a slow horn growth during their Ist year of life , whereas males did not. Level of polygyny of the species and environmental conditions experienced by the population could account for the occurrence of long-term cohort effects in male growth and its absence in female growth . Abundance of food resources throughout the study period allowed females t o show compensatory growth. However, evolutionary constraints on growth tha t may exist in males of polygynous species may have prevented males from sh owing compensatory growth.