Imagine stepping into a quiet forest at dawn. The air hums with anticipation as male birds gather in a clearing, each perched on their chosen display spot. Suddenly, the silence breaks, and calls, songs, and flamboyant movements fill the air. These birds are putting on the performance of their lives to win over potential mates. This is the spectacle of lekking, a behaviour as dramatic as it is fascinating.
Lekking is a courtship ritual where male birds, and sometimes other animals, gather in a specific area, known as a “lek,” to compete for the attention of females. Think of it as a high-stakes talent show where the males are the performers, and the females are the discerning judges.
A lek is usually an open, conspicuous area that allows males to show off their best attributes. Depending on the species, this might include singing elaborate songs, performing acrobatic dances, displaying brightly coloured feathers, or puffing up air sacs in their chests to create booming calls. The goal of being part of the lek is to outshine the competition and win the attention of visiting females.
While many males participate in the display, only a few, and sometimes just one, actually end up mating with the females. This creates an intense competitive dynamic, with males vying for prime display spots and giving their all to stand out in the crowd.
Lekking often follows a specific structure:
Central males: The dominant males usually occupy the best, most visible spots in the lek. They’re often the ones most likely to mate.
Peripheral males: Subordinate or less dominant males occupy the edges, where they might still get lucky but aren’t the main attraction.
Satellite males: In some cases, sneaky males hover nearby, hoping to mate with a female without putting on a full display.
For females, lekking provides an efficient way to evaluate many potential mates in one place. Instead of wandering across a territory looking for males, they can visit a lek and pick from the best of the best. Scientists believe this behaviour helps females ensure their offspring inherit strong, desirable traits.
Lekking is a behaviour full of contradictions. On one hand, it’s all about cooperation, with a group of males gathering in one spot, often peacefully, for the sake of courtship. On the other hand, it’s intensely competitive, with every male trying to steal the spotlight. Some males even team up, performing synchronised dances or calls to attract females, even if only one of them ultimately mates.
While it might seem like a lot of effort for limited payoff (since so few males get to mate), it works. Lekking has evolved independently in several bird species and even in insects, fish, and mammals. It’s a testament to how sexual selection can drive some of the most spectacular behaviours in the animal kingdom.
Lekking is not limited to just one family of birds, but is a behaviour that spans the avian world, from temperate forests to tropical rainforests and even grasslands.
In the open moorlands and grasslands of Europe and Asia, black grouse gather at dawn. The males, known as blackcocks, fan their distinctive lyre-shaped tails and puff up their white undertail feathers while making a bubbling, cooing call. These displays often involve dramatic confrontations where males face off, flutter, and leap into the air, trying to intimidate their rivals. Females, called greyhens, arrive to observe the action and choose the most dominant, energetic males as mates.
The great bustard, one of the heaviest flying birds, puts on a display as grand as its size. Found in Europe and Central Asia, the males gather on open grasslands to show off their strength and stamina. During the lek, a male will inflate special air sacs in his neck, ruffle his long neck feathers, and fan his tail feathers, creating an impressive and slightly comical puffed-up appearance. This spectacle is enhanced by their deep, resonant calls. Dominance plays a huge role with only the largest and most visually impressive males tending to mate.
In the tropical rainforests of New Guinea, the lekking behaviour of birds of paradise is a dazzling display of evolution’s creativity. Males have evolved elaborate plumage, including iridescent feathers, long tail streamers, and intricate patterns. Some, like the greater bird of paradise, perform highly choreographed dances, using tree branches as their stage. Others, like the superb bird of paradise, transform their bodies into almost unrecognisable shapes, creating a surreal display.
Manakins, found in Central and South American forests, are known for their acrobatic and highly synchronised courtship displays. Males of some species, like the long-tailed manakin, team up in pairs or small groups to perform intricate dances. These routines can involve moonwalking-like movements, flips, and even coordinated wing snaps that create popping or buzzing sounds. Interestingly, only the dominant male in the group mates, but the younger males in the troupe benefit from practising their moves for future seasons.
In wading birds like the ruff (Calidris pugnax), lekking takes on a unique form. Male ruffs sport dramatic breeding plumage, with extravagant ruffs of feathers around their necks and vibrant colour patterns. They gather on leks to perform a mix of territorial posturing and energetic displays. Some males adopt alternative strategies, that rely on tactics to secure a mate without participating in the main show. The diversity of male strategies within a single species makes sandpipers especially fascinating in the context of lekking.
Lekking is an example of sexual selection, one of the two main mechanisms of natural selection first described by Charles Darwin. While natural selection favours traits that increase survival, sexual selection favours traits that increase reproductive success. Lekking provides a unique lens through which we can observe how these forces shape behaviours, physical traits, and even evolutionary trade-offs.
In lekking species, males compete intensely for female attention by displaying their most extravagant traits, whether it’s colourful plumage, elaborate dances, or booming calls. Females, in turn, choose mates based on these displays, selecting the males that exhibit the most desirable traits. This selection pressure drives the evolution of these traits over generations, often resulting in the extreme ornamentation and behaviour we see in species like birds of paradise or ruffs.
But why would females prefer such seemingly arbitrary traits? The answer lies in indicator models of sexual selection. Extravagant traits are often costly to produce and maintain, so only the healthiest, strongest males can afford them. By choosing a male with these traits, a female ensures her offspring inherit “good genes” and traits linked to overall fitness and survival.
One of the most intriguing theories linked to lekking is the Fisherian runaway model, first proposed by geneticist Ronald Fisher. This model suggests that a female’s preference for a specific trait and the male’s expression of that trait become genetically linked over time.
If a female prefers males with, say, brighter feathers, her offspring will inherit both her preference and the male’s bright plumage.
Over generations, this preference becomes more widespread, and the trait becomes more exaggerated.
The process continues until the trait becomes so extreme that it begins to hinder the male’s survival (e.g., long tails that make flight less efficient).
This creates a paradox: why would evolution favour traits that are detrimental to survival? The Fisherian runaway highlights the tension between natural and sexual selection. In lekking birds, the benefits of attracting mates and passing on genes outweigh the survival costs – at least until the balance tips.
The problem is that in lekking birds, unlike in peacocks where males have evolved extreme tails due to sexual selection, no such runaway has been observed. Many scientists have attempted to explain why this may be, but the paradox remains.
Lekking presents a fascinating problem for evolutionary biology: if females are consistently selecting the most attractive males, shouldn’t the genetic diversity of these traits decline over time? This is known as the lek paradox.
In theory, “good genes” should spread throughout the population, making males more or less identical and giving females little reason to choose one over another. Yet, in practice, lekking species maintain a surprising amount of variation in male displays. Scientists believe this is due to several factors:
Hidden Genetic Variation: Even if certain traits appear uniform, underlying genetic variation may still exist.
Environmental Influences: Traits like plumage colouration or courtship stamina may vary depending on environmental conditions, such as diet or parasite load.
Mutation and parasite resistance: Mutations constantly introduce new variation, while selective pressures like disease ensure that traits signalling health remain relevant.
Lekking displays are often examples of honest signalling, where extravagant traits reliably indicate a male’s quality. For example, a bird with vibrant feathers or elaborate dances likely has the energy, health, and genetic resilience to sustain such displays. These traits are costly to maintain, so they act as a filter: only the strongest males can “afford” them.
For females, choosing a mate with honest signals ensures their offspring inherit genes that will help them survive and thrive. This creates a feedback loop where males with the best displays are more likely to reproduce, pushing the evolution of traits even further.
Lekking provides a dramatic stage where sexual selection plays out in its purest form, free from many of the pressures of survival selection. It’s a system that highlights the complexity of evolution, showcasing how competition, choice, and cooperation shape species over time. From the paradoxes of genetic diversity to the stunningly extravagant displays of lekking birds, this phenomenon remains one of nature’s most fascinating spectacles.
