Researchers from Université de La Réunion, Réunion, have found that Barau’s petrels synchronize their migration with the full Moon when travel to mating sites on Ile de La Réunion.
“First arrival at the colony is crucial in the mating system of colonial animals like seabirds,” said Patrick Pinet of Université de La Réunion, the lead author on a paper, published in the journal PLoS ONE.
Barau's Petrel (Peter Kappes)
The study reveals that contrary to some birds, which perform latitudinal migration, Barau’s petrel migrates longitudinally along the equator.
“This species makes longitudinal migrations although most seabirds perform latitudinal migrations. It thus remains in the tropical zone with slight photoperiodic variations during its whole life cycle. Barau’s petrel represents therefore a relevant model to study the relationships between photoperiod and the behaviour of tropical seabird species,” said researchers.
“Firstly, the annual activity of birds exhibited seasonal changes in activity according to their annual cycle with a lower proportion of time on water during the breeding compared to the non-breeding stage. The increase in ecological constraints from a growing chick across the breeding season, as regular returns to the colony and higher energetic demands, may explain the higher flight activity during this period. Secondly, migration dates of Barau’s petrels were consistent between years and seem to be linked to photoperiod.”
The researchers selected Barau’s petrel (Pterodroma baraui) because it exhibits a predictable annual timing of breeding and migration.
These birds are more active when the full Moon is out, spending more than three quarters of their time in flight rather than on the water.
The researchers concluded that the increase in activity is triggered by need of Barau’s petrels to hunt for prey, something that is easier for them to do when moonlight is available.
