Citizen Science Data Reveals The Cryptic Migration Of The Common Potoo Nyctibius Griseus In Brazil

The Common Potoo Nyctibius griseus is abundant, charismatic and generally considered to be sedentary across its range. Using citizen science data from eBird and WikiAves, we demonstrate that the Common Potoo may be a partial migrant whose breeding populations depart southeastern Brazil, Uruguay and northern Argentina in May to August during the region's austral winter. MaxEnt models revealed that spatio-temporal shifts in Common Potoo distributions were driven by seasonal changes in temperature and precipitation. We examined potential seasonal detection biases by restricting our analysis to daytime observations and testing for seasonally dependent shifts in distribution for two nocturnal non-migratory species. Our results provide the first evidence of migration for any member of the family Nyctibiidae. Our approach exposes the potential value that WikiAves data offer towards elucidating seasonal movements of South American birds.