PRIETO C, TAKEGAMI C, RIVERA JM Population structure of Morpho sulkowskyi Kollar, 1850 (Lepidoptera: Nymphalidae) in the western Cordillera, Cauca department (Colombia). Entomotropica 20(1): 15-22. Between the months of April and August of 2003 we stimated the Morpho sulkowskyi population size in a site of the western mountain range in the department of the Cauca by means of three methodologies of mark-release-recapture (MRR): Peterson, Jolly-Seber and Schnabel compared with the method of abundance by observation of Pollard. We captured 152 individuals with a recapture success of 23.68%. The ages structure and the recapture success showed that this is a nonconfined population with an emergency tip between July and August. The size of the population varied between 9 and 348 individuals. The residence time average was 3 days and the maximum observed measured for males was 8 days. The number of captured and recaptured individuals showed a positive correlation with the monthly average temperature. The individuals flew mainly between 9:00 and 14:00 hours; and when the temperature was higher than 15 o C.