In Antarctica, the rocky beaches are basically the entire shopping district. There aren’t any twigs or grass - so when a male Adélie penguin wants to build a nest and find a mate, he has to use pebbles. And he picks them very carefully.
He’ll wander the beach, comparing stones, until he finds the one he thinks is just right - smooth, perfectly sized, maybe a little shiny. Then he waddles over to a female he likes and drops the pebble at her feet. If she accepts, the pebble becomes part of the nest they build together, and the pair will usually return to each other every year for life.
It’s not all sweet - penguins also steal each other’s pebbles when no one’s watching. But the original gift always counts. And in the middle of winter, when temperatures drop to -40°F, emperor penguins keep each other alive by huddling in tight crowds that slowly rotate, so every bird gets a turn warming up in the middle.
