An assay to investigate initial orientation in nocturnally fledging seabirds

Submitted by Johan on 4 February 2021.

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Shearwaters and petrels are some of the worlds greatest travellers. The migration of adult Manx shearwaters has been documented by use of small biologging devices. It showed that those seabirds fly from UK, across the globe, to the South Atlantic. Not much is known, however, about the migration of juvenile Manx shearwaters due to their low survival rate and prolonged time before they come back to breed on their natal island.

Photo by Joe Wynn

We explored the first minutes of the maiden flight of nocturnally fledging juvenile Manx shearwaters by attaching a small LED to a the back of the birds. This allowed us to observe, using binoculars, this remarkable moment in the life of a seabird - their first flight. By attaching a small box with a magnet (experimental) or a glass bead (control) to the head of the bird, we investigated if the orientation of a young seabird could be disturbed by a magnet. We did not find a difference between the control and the experimental group, but we observed other factors that influenced a young seabird’s departure from its natal island. Juveniles flew with a wind component between a crosswind and a tailwind, often observed in young, inexperienced seabirds, suggesting a learning phase of flight. Furthermore, young shearwaters oriented towards the sea, where they could forage, and away from land where they could be depredated.

Photo by Joe Wynn

This assay could potentially be used in other species of birds that are typically difficult to research due their low chance of recovery or those that are unsuitable for large tracking devices.

The paper is Open Access and can be downloaded here: