Male Adelie penguins give females smooth pebbles to ask them to be their mate.

Adelie penguins live in Antarctica and breed during the spring months of October and November. Male penguins arrive at their breeding areas first and immediately start looking for the best pebbles they can find.Scientists have watched these penguins for over 60 years. They found that males spend about 3 hours each day searching for stones. They walk up to 1.5 kilometers away from their nesting area to find the right pebble. The best pebbles are smooth, round, and about the size of a large marble.When a male finds a female he likes, he presents his chosen pebble. Research shows that 73% of females accept the pebble offer. If she takes it, they become mates for that breeding season. The pebble becomes the first stone in their nest.Building a complete nest requires 50 to 100 stones total. The nest protects their eggs from the freezing Antarctic temperatures that can drop to -40°C. Males who give better quality pebbles have much higher success rates at finding a mate and raising chicks. Some males have to try up to 12 different pebbles before a female accepts one.