Magellanic penguins gather at their breeding colony after returning from long journeys at sea
Magellanic penguins are smarter ocean travellers than previously thought, according to a new study involving researchers from Swansea University’s Animal Movement Lab. The findings reveal that these penguins use tidal currents not only to return home more efficiently, but also to forage for food along the way.
Published in PLOS Biology, the researchers tracked 27 adult penguins during their return trips from foraging in the ocean off Argentina. Led by the Max Planck Institute of Animal Behaviour, the team discovered that instead of swimming in a straight line back to their nests, the penguins often followed curved, S-shaped paths shaped by the tides. These routes helped them conserve energy and take advantage of feeding opportunities.
Co-author Professor Rory Wilson of Swansea University’s Animal Movement Lab explains: “We used small high-tech tracking devices with GPS and compasses, combined with detailed ocean current models. These revealed that penguins adjusted their swimming direction depending on the strength and direction of the currents. In calm water, they headed straight for home, but when the currents were stronger, they allowed themselves to drift sideways. This made their journey longer, but less tiring.”
This strategy also gave the penguins more chances to feed.
“The penguins were observed diving and foraging for food during much of their return journey,” said Professor Wilson. “As they got closer to the colony, they became more focused and swam more directly, often arriving within just 300 metres of their original departure point — an impressive level of accuracy after journeys of up to 75km.”
The researchers considered two logical strategies the penguins might use to return home. Theoretically, and assuming that the penguins ‘knew’ where they were, because they cannot see land when they are far out at sea, they would appear to have two obvious options as to how to get home. The ‘naïve’ approach would be to always head directly for the colony regardless of current strength or direction – something humans caught in rip tides or rivers are prone to doing. However, in strong opposing currents, the penguins doing this would have to work extremely hard.
Indeed, currents in their region may be up to 4.5mph – roughly equivalent to speeds of the best Olympic swimmers and although penguins – which cruise at about 4.5mph - can easily travel faster, it costs them lots more energy. The smarter ‘navigator’s option’ is to swim at an angle to the colony so that the combined effect of the penguin swim speed and direction and that of the current results in an overall movement towards the colony. This is far more energy efficient. However, it assumes that penguins can somehow compute or perceive the effect of the current and correct their heading accordingly.
Surprisingly, the penguins don’t strictly follow either strategy. “Actually, penguins do neither!” said Professor Wilson. “Their approach is more flexible. They seem relaxed about being at sea — sometimes swimming with the current even if it doesn’t take them directly to their nest. Occasionally, they shoot past the colony and down the coast.”
What’s remarkable, Professor Wilson adds, is that penguins appear to sense both the presence and strength of currents, even when there are no visible cues: “Penguins seem able to determine when they are in a current and roughly how strong it is. They also appear to understand the tidal cycle — that water moves first in one direction and then reverses. If they’re carried too far by the incoming tide, they seem to know they’ll be brought back by the outgoing tide later.”
These findings offer new insight into how Magellanic penguins adapt their movement strategies in dynamic environments. They also provide a broader framework for understanding how other marine animals, such as seals, turtles, and seabirds, may respond to increasingly dynamic ocean conditions driven by climate change, including intensified currents, shifting prey distributions, and altered thermal fronts.