Vocal Activity of the Great Potoo (Nyctibius Grandis) in Relation to Moonlight: Detections in Costa Rica

Abstract

Variations in moonlight can affect the vocal activity of many nocturnal birds, including the Great Potoo (Nyctibius grandis), a rarely seen bird usually detected through its characteristic calls. We evaluated the vocal activity of the Great Potoo in relation to moonlight in a Tropical Forest of Costa Rica. We surveyed potoos using four replicated 13-minute counts covering a single moon cycle at 31 points at La Selva Biological Station during March and April 2020. We detected seven Great Potoos on nights with 76-100% moonlight, three on nights with 51-75% moonlight, and none on nights with 0-50% moonlight. Great Potoos were more easily detected during moonlit nights, which is consistent with other studies of ‘lunarphilic’ nocturnal birds, and suggests that future studies modeling occupancy or habitat use of Great Potoos should consider moonlight as a covariate of detectability.