When a male penguin falls in love with a female penguin, he searches the entire beach to find the perfect pebble to present to her.

natgeoPenguinsPenguins sharing pebbles   © National Geographic

Humans give flowers and candy when impressing a lady. Penguins give rocks. Not just any rocks, though — male Gentoo penguins search through piles of pebbles to find the smoothest, most perfect ones. When a penguin has selected his pebble, he presents it to his intended companion. If she approves, she puts the stone in her nest and the two are well on their way to becoming mommy and daddy birds. Pebbles are so important to the penguins that males often fight over the prettiest selections.

Penguins are birds that build nests for laying eggs. Their environment in the Antarctic restricts them in their choice of materials to line it with. Gathering up small stones and pebbles scattered on the ice, they line the ice hollows to make a nest.

Adelie Penguins are known for “pebble envy” within the group, with sneaky male penguins trying to nab the best looking pebbles from other nests for their own sweetheart. Male Adelie Penguins prepare the base of the nest while the female arrives later to collect the final most important items while the male guards the now valuable collection of pebbles.
So off the females go, having to search further and further afield for stones. While they are away, other female Adelie Penguins continue to arrive at the nesting ground. Many of these will be younger, less fit birds who are still unattached. Spying a healthy-looking male with a nice nest, they will quite often take the opportunity to try and jump into the situation and seduce him. However, if the returning female discovers them, she will face the abuse of a sharp beak as the outraged spouse re-asserts herself.

There are, of course, a lot of young single males around. The female Adelie, when selecting her mate, assesses the fitness and body weight of the prospective partner. The male, after all, will have to stand guard on the eggs and keep them warm during the incubation period, so the females are looking for podgy partners with sufficient paunch to see them through the long, cold days ahead. But, being blokes, the young males don’t want to miss out on any mating that might be on the go so they have developed a cunning ruse.

During the initial ritual in the hunt for stones, the young males collect a cache of their own, even though they do not intend to build a nest. Instead, they position themselves slightly away from the nests, close enough that the females searching for pebbles have to pass them. As the females approach, their eyes scanning the ice for pebbles, the young males will invite the females to get some rocks off them.
It is at this point that, faced with the prospect of a long hunt for pebbles in the cold, some females are tempted. Many females will make their way over to the young males and begin flirting, often ending up prone on the ice with their pleasures on display. If a young male accepts the invitation, the female will collect a pebble as payment after the nefarious deed is done and return to her waiting partner at the nest who is none the wiser, or at least seems undisturbed.

Researchers have also witnessed the extremely skilled flirt type of female Adelie Penguins who will go through the same flirting routine as the others but, when a male makes a move, will swiftly grab a pebble and beat a retreat. The young males do not seem to mind this if the preceding show was satisfactorily stimulating. Indeed, some females have been seen to tease in this way up to sixty times with the same males.

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