En route activity of Chilean Elaenia, a long‐distance migratory bird in South America

The logistics of measuring activities that occur at fine temporal scales, such as short stopovers that last a few hours, has proven very challenging when studying small migratory birds. Here, we deployed multi-loggers equipped with an accelerometer and thermometer on Chilean Elaenia ( Elaenia chilensis ) to evaluate their activity patterns while they undertook their annual migration from their Patagonian breeding grounds to non-breeding zones in Brazil. Results show that elaenias can fly at altitudes of >1500 masl and migrate nocturnally, providing the first evidence of this behavior in a Neotropical austral migrant. Although most migration flights lasted less than 8 h, one individual flew non-stop for more than 28 h. Overall activity patterns (e.g., flight and stopover duration) were not substantially different between pre- and post-breeding migration. This technology offers a window into the migratory behavior of small birds that migrate within the Neotropics at a finer temporal scale than previously possible.