Activity of Oophaga pumilio was monitored on Isla Colón, Republic of Panama. I quantitatively determined the number of vocalizing male frogs and investigated differences in hourly total activity and hourly calling activity and the influence of weather conditions such as temperature, humidity, light intensity and rainfall on total activity and calling activity during the day. 17 There was a statistically significant difference between hourly time intervals for diel calling activity in the dry season, and a positive correlation between calling activity and light intensity. Overall calling activity was high between 10:30 am – 11:30 am, while calling activity was at its lowest early in the morning and late afternoon, and at its highest 9:30 am - 12:30 pm. There was no significant difference between total activity and temperature, total activity and humidity, total activity and light intensity, total activity and rainfall, calling activity and temperature, calling activity and humidity, calling activity and rainfall.