Like in most families, mealtime in owl nests can get a little rowdy. But among barn owl nestlings, competition over food is actually relatively civil: According to a new study, these avian siblings vocally communicate the extent of their hunger, and the less hungry step aside for the famished to eat their fill first.
In a study in the journal Behavioral Ecology and Sociobiology (as reported by Audubon), ecologists at the University of Lausanne in Switzerland placed 27 young barn owls in fake nests with several mice, and played recordings of earlier sibling calls at different rates, monitoring how the sounds affected eating behavior. This was designed to simulate situations in which owl parents drop off food that can be divided up between multiple chicks, rather than forcing the nestlings to compete over a single piece of food. The recorded calls came from owl chicks that had not eaten in 28 hours.
While the owls who heard the faster playback (indicating greater hunger) ate the same amount as the chicks who heard the slower playback (a noncompetitive call) over the course of the night, those who heard “siblings” crying faster for food paused before eating, waiting for the playback to stop. These chicks ate significantly less over the first five hours of the night, but then ate more to compensate during silent periods.
When the owlets were alone, they didn’t vocalize any more than usual before eating, but when together, the parliament of owl siblings chattered before chowing down, suggesting that the vocalizations are communication-related, rather than simply related to the act of eating. “In barn owls, our results suggest that siblings vocalize to signal their intention to consume part of a food stock, a behavior that efficiently deters siblings from competing,” the researchers write, perhaps because it’s evolutionarily advantageous not to provoke your siblings into attacking you.