Leg rings impact the diving performance of a foot-propelled diver

GÓMEZ-LAICH, A.; PANTANO, C.; WILSON, R. P.; SVAGELJ, W. S.; YODA, K.; GUNNER, R.; QUINTANA, F.

IBIS

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2022 vol. 164 p. 118 - 131

0019-1019

Leg rings are frequently used to mark aquatic birds in order to identify individuals, study population dynamics and migration patterns with the proviso being that the rings should not affect the birds. The effects of tags and rings are of particular interest in diving birds because any change in body shape could impact swimming efficiency and costs since water is almost a thousand times denser than the air. We attached tri-axial accelerometers to both ringed and unringed breeding Imperial Shags Leucocarbo atriceps to assess dive performance based on descent angle, descent rate, power stroke rate, power stroke peak acceleration amplitude, and Vectorial Dynamic Body Acceleration (VeDBA) as a proxy of energy expenditure. Ringed birds, especially females, had a higher foot-stroke amplitude than unringed animals. In addition, the overall efficiency of the ringed individuals, as expressed by the descent rate per unit VeDBA, was compromised (by some 3.5 % in females and 4.3 % in males) compared to unringed birds. We conclude that leg rings change the diving performance of Imperial Shags although the effect is small and may not affect reproductive success. However, given that birds are typically ringed for life, we urge researchers to be particularly critical about the potential cumulative effect of attaching leg rings to foot-propelled diving species.