Behavoral ecology and social organization of a dendrobatid frog (Colostethus inguinalis)

Summary

• 1. A population ofColostethus inguinalis, a small diurnally active frog, was studied along a stream in seasonal tropical forest on Cerro Campana, Panama, from January through November 1976. Females laid eggs on land and carried up to 40 tadpoles on their backs to water. Tadpoles remained on their mothers' backs for up to 9 days. Sexual maturity was reached about 4–6 months after metamorphosis.

• 2. Some females produced two clutches in 11 months. The average interval between clutches was 133 days. Reproduction occurred in every month except April, with a peak in May and June, the beginning of the wet season. Reproduction decreased in the wettest months.

• 3. C. inguinalis has three vocalizations: an advertisement call, an encounter call used to challenge territorial intruders, and a close-range encounter call given just before an attack. The first two are given only by males, the last by females as well.

• 4. Agonistic behavior included postural displays, chases, attacks, and wrestling. Encounters between same sex individuals were more likely to end in wrestling than those between males and females. Males were more effective than females in repelling intruders without physical contact.

• 5. Courtship was prolonged and involved closerange vocal, visual, and tactile interactions between males and females.

• 6. The behavior and spatial organization of males and females changed seasonally. Both sexes defended small territories near pools in the dry season, although males remained in one place longer than most females. In the wet season, males defended widely dispersed territories ten times the size of dry season territories. Females were more mobile and seldom defended territories for more than a few days at a time. Dry season territories appeared to provide access to moist retreats and feeding sites in short supply. Large male wet season territories were used for feeding, shelter, courtship, and mating.

• 7. Both males and females defended territories against frogs of other species, but only encounters between maleC. inguinalis and maleColostethus pratti were frequent. Most of these occurred in the dry season, when the two species competed for the same retreats. There is some evidence that the two species can perceive each other's vocalizations.