Why penguins ride the currents instead of swimming straight home

Magellanic penguins are expert navigators. A new study shows they don’t just head straight home from foraging trips. They ride ocean currents and tides, save energy, and grab snacks along the way.

A research team led by the Max Planck Institute of Animal Behavior and Swansea University tracked 27 adult penguins returning to their colony in Argentina.

The results showed that penguins don’t follow the shortest path. Instead, they adopt curved, S-shaped routes shaped by tidal flows. These winding paths help them conserve energy and find more food.

Penguins ride ocean currents to save energy

The researchers analyzed GPS and compass data combined with ocean current models. This revealed a clever strategy.

“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.”

These paths aren’t random. Penguins adjust their heading to balance effort and direction. The team developed travel vector models to track how birds moved with or against currents.

When needed, penguins angled their swims to work with water movement. This created more efficient ground movement, even if the direction wasn’t perfectly straight.

Feeding while floating home

Along these ocean current-driven, drift-friendly paths, penguins often dove deep to hunt. Most kept diving for prey during nearly 80% of their return trip.

Dive depth and prey capture activity decreased as the penguins neared the colony, showing a transition from feeding to focused homing.

“The penguins were observed diving and foraging for food during much of their return journey,” said Professor Wilson from Swansea University.

“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.”

These dives weren’t random. Penguins often deviated from a straight path to hunt, showing opportunism in action. The strategy paid off. They traveled efficiently without needing to swim straight the whole time.

Penguins use a flexible ocean route 

The study tested whether penguins used either a simple straight-line strategy or a complex angle-correction approach.

“Actually, penguins do neither! Their approach is more flexible,” said Professor Wilson. “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.”

Instead of fighting the flow, penguins accept some drift. The tides in San Matías Gulf alternate directions every 12 hours. This helps balance out sideways drift across the full journey. By planning loosely around this cycle, penguins avoid constantly battling currents.

How penguins sense ocean currents

Penguins likely don’t see land for most of their return. So how do they know where they are?

“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,” said Professor Wilson.

“If they’re carried too far by the incoming tide, they seem to know they’ll be brought back by the outgoing tide later.”

The study suggests that the penguins don’t rely on seabed features or landmarks. Instead, they may use a mix of compass orientation, smell, and detection of flow against their body.

Some penguins returned at night, meaning vision alone can’t explain their precise homing.

Currents help more than they hurt

The team ran simulations where penguins always swam straight home. These “naïve” agents, which ignored the effects of ocean currents, often missed their target by many kilometers.

Real penguins, with their flexible strategy, consistently returned within 300 meters of their starting point. This accuracy shows that adjustment, not stubborn straight-line effort, is key.

Swimming against ocean currents costs energy. Penguins avoid that by letting the ocean currents carry them when helpful and correcting only when needed. The study measured energy use using an “ease of transport” score, like a fuel-efficiency rating.

Penguins’ real-life paths scored better than the theoretical “optimal” path when overall energy use was considered. They sacrificed some directness for efficiency and still ended up close to home.

Other animals may use similar strategies

These findings reveal just how well Magellanic penguins manage complex conditions. Their strategies may also reflect how other marine animals, like turtles or seals, adapt to changing seas.

As ocean conditions shift with climate change, species that adjust their movement patterns, like these penguins, may have the best chance of thriving.

The penguins’ flexible, energy-smart behavior could inspire new ways to understand marine navigation across species.

The study is published in the journal PLOS Biology.

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