Magellanic Penguins Spheniscus magellanicus commuting through San Julian Bay; do current trends induce tidal tactics?

Abstract

The behaviour of Magellanic Penguins Spheniscus magellanicus commuting between their foraging areas and breeding areas in San Julian Bay, Argentina, was studied to examine whether tidal rip currents affected travelling patterns. Although there was no apparent relationship between departure and arrival patterns and the state of the tidal cycle, birds travelling against the current dived for longer periods and a shorter rests on the surface than birds travelling with the current. In addition, bird swimming against the current hugged the banks of tidal rivers much more closely than did birds swimming with the, thus, reducing the magnitude of the current against which they had to swim. In cases of extremely high current speeds, birds travelling upstream walked. Models regarding the energetics of movement indicate that the strategies adopted by Magellanic Penguins can result in substantial energy savings.