Porcupines of the genus Coendou are among the least studied mammals in the Neotropics. The Stump-tailed Porcupine, Coendou rufescens, is distributed in the Andean region from Colombia and south to Bolivia. Despite its wide distribution, nothing is known about its natural history, besides observation of banana consumption in captivity. Here we present new observations on the feeding habits, diurnal activity, and the use of the tail for support during feeding obtained by means of collaborative (citizen) science. We also comment on its locomotion on land and in trees. We observed five diurnal events of C. rufescens feeding on infructescences of trumpet tree (Cecropia angustifolia Trécul). During the feeding activities, the Stump-tailed Porcupine used the tail for stability and support. These are the first observations of such behavior in the wild for this species and suggest a more diurnal activity for this species which belongs to a group of rodents traditionally considered to be predominantly nocturnal.