December 6, 2021

I, Science

The science magazine of Imperial College

Emily Mobley takes a look at the extraordinary and beautiful courtship behaviours of animals large and small

peacock eric kilby 4512923662_b860b92524_b

In nature, the competition to win a partner can be so intense that it creates both extraordinary beauty and bizarre courtship behaviours. Success in nature is all about creating the next generation, and various males do whatever it takes to communicate their fitness and win over choosy females.

Say it with Flowers

The BBC series Spy in the Pod gave a turtle’s-eye view into the courtship behaviour of bottlenose dolphins. In the breeding season, young males swim together in bachelor pods seeking out pods of females. To impress a female, the male dolphin will spend hours searching for the perfect strand of seaweed which he then tosses around in the water to show off his agility, before presenting it to her like a bunch of flowers.

marine flatworm Steve Childs 233603352_95c54f32bd_bMake War, Not Love

Whilst brightly coloured marine flatworms may look graceful as they glide through the water, for them the mating game is a battlefield. Marine flatworms are hermaphrodites, and possess both male and female sex organs. When mating, the flatworms must decide who takes on the more costly maternal role in reproduction. The negotiation takes the form of ‘penis fencing’, a type of combat during which the two flatworms rear up and expose their penises to try and stab each other. The two flatworms fight it out for up to an hour until the ‘loser’ is inseminated, and must take on the role of the female in producing offspring.

My Eye Spots Are Up Here

In one of the most renowned displays of animal courtship, male peacocks show off a brilliant array of feathers which make up a five foot tall tail, dotted with brightly coloured eye spots. The choosiness of peahens has driven the evolution of this giant tail in males, which acts as a sexual handicap in that it makes him more vulnerable to predators but more sexy to females.

However, studies have shown that perhaps peahens aren’t so interested in the elaborate tail, but more the courtship dance. Using eye-tracking technology, researchers found that peahens pay more attention to the male’s legs and the lowest edge of the tail feathers; she rarely gazes into his eyes – neither those on his head or in his tail. In particular, when he turns his back and rustles his little white tail feathers in the dance she is the most attentive. Therefore it may be that size doesn’t matter when it comes to peacock’s tails, but more how he uses it in his dance moves.

Deadly First Dance
MalePeacockSpider_1024wFor a male peacock jumping spider who’s only the size of a grain of rice, almost anything can be dangerous – but most of all, a potential mate. In Australia, the male spider seeks out a female by following a scented strand of her silk. Along the way he encounters previous victims of similar endeavours; the female is not amorous, and kills every male that doesn’t match her expectations. However, his argentine tango may win her over. When he meets the female, a complicated dance routine commences. He waves his third legs in the air and raises his brightly coloured abdominal flap, like a peacock’s tail, attempting to seduce her. Meanwhile she attacks him continuously. Finally she succumbs and allows him to mate with her, then kills him anyway – after all his body makes the perfect meal to nourish her eggs.

The Artist

At the bottom of a bay in Japan, a small grey Japanese pufferfish is almost invisible on the ocean floor, so to attract a female’s attention he has become one of nature’s greatest artists. Using his fins as his only tools, he follows a plan of mathematical perfection in his head and ploughs the sand, breaking it up into fine particles. He removes shells and uses them to decorate the peaks of his masterpiece, which he must work on 24 hours a day for a week to protect it from the ocean currents. The result is an astonishing, geometrical crop circle in the sand.

A female, bulging with eggs comes to inspect his creation before leaving to await the final stage. By the next morning the male has moved all of the softest sand to the middle, creating a soft bed ready for her eggs. When she lays her eggs in the heap of sand, the male grasps her cheek with his beak and fertilises them, before flicking his tail to bury the eggs. After an hour of rough affection, which leaves a love bite on her cheek, she finishes laying her eggs and leaves the male to stay and fan the eggs until they hatch.

long-tailed manakin steve garvie 4682605165_540c16458c_o croppedFeathered Wing Man

A male long-tailed manakin bird has the task of trying to impress one of the world’s choosiest females. He has been practicing his moves for nearly a decade in the Costa Rican jungle, and is joined by another male – not a rival but his junior partner. The master and apprentice co-ordinate their courtship dance routine and know each other so well that they can finish each other’s calls. The female expects perfect harmony so they must practice together every day. She is a dull green colour, in contrast to their black plumage with blue back feathers, red caps and long tails. To court her the males dance in synchrony, jumping up into the air, swapping positions and harmonising their calls. When they win her over the apprentice is banished and only the master gets to mate; there is no reward for the apprentice until his master dies and he can take his place.

The Stage is Set

In the forests of Papua New Guinea, a bright yellow bird with a red hood creates a stage. The flame bowerbird possesses an eye for detail as he builds a bower out of twigs, before painting it with mud to create a darker background to set off his magnificent plumage. He spends a week building and dressing the set with leaves, bright blue berries and flowers, before he calls for a female and waits.

When a female visits, he lures her into the bower before he starts the show. First he mesmerises her by dilating his pupils alternately, then limbers up by stretching out his wings and letting out a wheezy call from deep in his throat. During his grand performance he looks over his shoulder and waves his wing like it’s a matador’s cape, vibrating his body up and down. She gives him a hint by picking up a blue berry, which he uses as a prop in his dance. When she’s really interested, he gets physical and head butts her chest.

Emily Mobley is studying for an MSc in Science Communication

Images: Peacock display (Eric Kilby, Flickr)Pseudoceros bifurcus – Blue Pseudoceros Flatworm (Steve Childs, Flickr); Male peacock spider (Wikimedia Commons)Long-tailed Manakin (Chiroxiphia linearis) (Steve Garvie, Flickr)