As the Copacabana field station research presses on, new questions concerning diet, foraging habits, and chick rearing are asked. How far do penguins have to travel to find a reliable source of food, and how much time do they spend away from the nest on foraging trips?
For the Love of Krill
Antarctic krill, tiny, shrimp-like crustaceans, are one of the primary food sources for Adèlie, Gentoo, and chinstrap penguins in the Western Antarctic Peninsula. Most of a krill’s life is spent in open ocean or aggregating under ice with millions of other krill to feed on the plankton and algae that grows beneath the sea ice. Recent studies have indicated that increasing global temperatures have significantly decreased the amount of ice in the Western Antarctic Peninsula. Without this critical habitat for krill, their populations have seen a sharp decline, which is not very good news for the penguins. Now, more than ever, is an important time for researchers to gather as much data about these changing ecosystems as possible.
© Troels Jacobsen | Oceanwide Expeditions
What is a “Krill Gut”?
Weeks pass by, and soon, the first fluffy chicks begin to emerge from their eggs. It’s now up to the adults to catch enough krill to feed two mouths, which means longer foraging trips, and more time spent away from the nest.
When the chicks start hatching, it’s never too difficult to spot a new parent. Upon their arrival back to shore from a foraging trip, the penguins appear to be filled to the brim with krill. Down the beach they lumber, their distinctive waddle even more exaggerated now, making the occasional stop to catch their breaths. Their bellies grow so large, that it is sometimes difficult for them to see what’s in front of them as they make their way down the beach. Rocks and other beach debris can quickly become tripping hazards. It may be more efficient in some cases to roll them back to their chicks. This over-inflated look is affectionately referred to as a “krill gut”, and is an exciting sight for any young, hungry chick.
When the parent finally makes it back to the nest, it’s time to regurgitate a portion of krill to each chick, and let the other parent go out to forage for more food. It’s a nonstop feeding frenzy for the first few weeks of the chick’s life, and an exhausting time for the scientists who have to keep track of these patterns.
After observing the penguins’ mating and chick-rearing behaviors for several weeks, it’s time to solve another crucial piece of the penguin puzzle: how far do the penguins travel to find food? First, five individuals of each of the three species of penguin must be caught and fitted with a satellite transmitting device (a PTT or Platform Transmitter Terminal) that records their geographic location and their diving depths when they’re out foraging.
Catching the penguins is no easy task. It usually takes one person to catch them with a net, and two more just to carefully hold onto them while the tag is fitted. The tag, the size of a small candy bar with an antennae attached, is fitted onto their lower backs with epoxy glue, which reduces drag while they swim. The epoxy glue causes no harm to the penguins, and the feathers that the glue is attached to are shed at the end of the summer.
The tags begin recording data as soon as they are attached to the penguins, and will not be seen again until they return to the island from their foraging trip. Upon their return, the penguins carrying the tags must be immediately recaptured and relieved of their data collecting duties. Again, the net comes out and the penguin’s tag is painlessly removed with a small pair of scissors.
Unfortunately, some penguins decide to migrate to a different island with their tags still attached, and others loose them in the middle of the ocean on their way back, which is bad news for scientists looking to collect as much information about the season’s krill availability and dining hotspots as possible. There’s never a 100% success rate with this method of data collection, but it’s currently the best technology that exists for these types of studies.
Back to School
As the months pass on, it becomes time for mom and dad to start teaching their young how to survive on their own. “Crèching” or “penguin school” is the time when groups of chicks from the same colony gather together to learn various behaviors. The adults don’t stray too far during this period, and can be found on the perimeter of the crèches, guarding their young from predators.
While it’s important to keep an eye on their young, it’s even more important to teach them that their parents, or any other adult penguin for that matter, are no longer a reliable source of food. Weaning the chicks off of mom and dad’s krill is no easy task. Hungry chicks can be seen chasing the adult penguins down the beach, and begging for krill. Even with such short legs, these penguins can move quickly.
Eventually, troupes of young penguins can be found walking around the island together, learning how to swim in shallow pools of glacial run-off, and cautiously inspecting anything that resembles krill. Soon, they will molt their chick-fuzz and grow their waterproof, adult feathers so that they can begin their migration through the ocean.
The chicks’ newfound independence also tells of the quickly approaching winter, and cues the scientists to begin packing up camp. Six months passes by quickly, but there’s always another season on the horizon to look forward to, for both the scientists and our Antarctica expeditions alike.
© Oceanwide Expeditions