Swimming Energetics and Performance of Instrumented Adélie Penguins (Pygoscelis Adeliae)

The effects of implanted and of externally attached instruments (1.8% of body cross-sectional area) were studied on Adélie penguins (Pygoscelis adeliae) using a 21 m long canal in conjunction with respirometry at Esperanza Bay, Antarctica. Penguins in both groups covered the same mean distance (173 m in 5 min) as controls. Implanted birds preferred to swim at slower speeds (1.3–1.7 m s⁻¹) than did the controls (1.9–2.1 m s⁻¹), whereas penguins with external instruments had a bimodal speed distribution with maxima at 1.7–1.9 and 2.3-2.5ms⁻¹. Power input during swimming averaged 20% less in implanted penguins (12.7 W kg⁻¹) and 42% more in penguins fitted with external instruments (22.5Wkg⁻¹) compared with controls (15.8 W kg^{− x}). Similarly, cost of transport was 23% lower in implanted penguins (7.0 J kg⁻¹ m⁻¹) and 25% higher in externally instrumented birds (11.3 Jkg⁻¹ m⁻¹) compared with controls (9.0 Jkg⁻¹m⁻¹). Possible reasons for the effects caused by the devices are discussed and the advantages and disadvantages of implanted and externally fitted devices are compared.