Imagine that you went out to buy shrimp but the closest grocery store didn’t have it in stock. Even then, the same store most likely has their selection of other seafood and meat for you to choose from, so that won’t be too devastating.
Adelie penguins can do the same: when they can’t get enough krill – a tiny shrimp-like crustacean that is their main source of food – they can switch to eating fish such as the Antarctic silverfish.
Such a switch can be triggered by a competitor for the Adelies’ food: baleen whales. When these whales arrived to the Antarctic in the spring to feed, they ate about 2000 times more krill than penguins would. Continue reading