Venezuelan oilbirds show varied migration patterns, study reveals

Researchers using tracking devices have documented three distinct foraging strategies among oilbirds, nocturnal birds that inhabit caves across South America. The study, which monitored 21 birds in Venezuela, revealed that individual birds employ markedly different approaches to locating and consuming fruit in tropical forest ecosystems.

One group of oilbirds exhibited a consistent pattern of nightly returns to their primary cave after feeding expeditions. A second cohort ventured out for several days at a time before returning, while a third group of five birds undertook significantly longer journeys, remaining away from their home cave for extended periods—with some absences lasting up to 73 days.

The extended-stay birds demonstrated energy-efficient behavior by reducing their nightly flight distances and establishing temporary resting areas closer to abundant food sources. This strategy contrasts sharply with the shorter-range foragers, who expended greater energy on flight. Researchers used movement-tracking devices to record flight patterns and duration, enabling detailed analysis of each bird's individual foraging behavior and energy expenditure.

The findings suggest that oilbirds possess considerable behavioral flexibility in adapting to food availability across different regions of their tropical habitat. This variation in migration and foraging patterns may reflect differences in local fruit abundance and individual bird preferences, offering insights into how cave-dwelling species optimize their survival strategies in dynamic forest environments.