Booming and strutting for sex
Channel: TerraNaturalist
Date: 2013-03-13

Matt Schulze provides this excellent footage of Lesser Prairie-Chickens attending a lek in New Mexico. Why do males join leks as opposed to defending all-purpose territories, as do most species of birds?  Why are male prairie-chickens so elaborately attired?  A few answers are provided below.
In spring, male Lesser Prairie-chickens gather on small plots of land where they fight each other and display to passing females. The intent of each male in such gatherings, called leks, is to persuade as many females to mate with him as possible. However, given the intense competition among contenders and the choosy disposition of females, it is difficult for any one male to successfully reproduce.
It is under such stringent conditions when natural selection produces some of its spectacular creations, which is certainly true for male prairie-chickens. For onlookers, it is impossible not to notice the conspicuous head-feathers, colorful inflatable cheek patches, and the bizarre habit of males stomping their feet.  And then there is the hypnotic booming and rhythmic sounds produced by multiple males simultaneously displaying. Presumably, most females visiting the lek are also impressed, but the task at hand for every male is to stand out above the crowd.
   Assuming that a female mates with only one male per breeding season -- and then only within designated display arenas -- having all males displaying together simplifies the task of choosing a sexual partner. It also logically follows, that for a male to have a chance of breeding, he is obligated to join a lek despite the fact that only a few dominant males will win the approval of the majority of females.
  Indeed, deciphering the dynamics of such an intricate mating system presents a host of mysteries. Why, for example, do multiple males choose to display together as opposed to each defending an exclusive and much larger multi-purpose territory to attract a mate?  Several interesting hypotheses have been proposed.
   Some biologists contend that subordinate males seek out the company of sexy males, because these so called "hotshot" performers are magnets for females. If this idea is true, the best chance for a young male to sire offspring is to mingle with the local Don Juans. On the other hand, convincing evidence also suggests that males gravitate to areas where females are likely to be, such as near heavily traveled corridors. Instead of males seeking out each other's company, leks may form near "hotspots," that is, near locations determined by the seasonal movements of females.
   In either scenario, however, choosing the best site for male Lesser Prairie-chickens to gather is, in part, determined by the suitability of the surrounding terrain. Stable leks, that are formed in the same locations each season, are typically situated in open country where females can simultaneously monitor multiple males and where males can spot approaching predators. Indeed, some lek sites are better suited than others which results in the establishment of local traditions.
  Here is second mystery concerning lekking birds, including prairie-chickens: why are males so elaborately attired and why do they perform so energetically?  Perhaps the intimate presence of multiple rivals makes it necessary for each performer to "go all out" to impress finicky females. This includes flaunting bright plumage and generating impressive sounds. Presumably, the more bells and whistles a male can employ the greater the chance he can intimidate rivals and more importantly, persuade females to copulate with him. Given that prairie-chickens on average live for less that five years, most males have few opportunities to breed.
   As a rule, males are not particularly choosy when comes to having sex while, in contrast, females can be very discriminating. Females are best served by selecting a mate that possesses good genes and is free of infectious diseases and parasites. They do this by looking for traits that inferior and unhealthy males cannot fake, at least not convincingly. All things being equal, males that have survived several years have either been extremely lucky or possess good genes. Needless to say, older males typically procure the best, centrally located sites within a lek.
   Based on their appearance and behavior, it seems impossible to discern in the video which males possess superior qualities. Do females also have difficulty making up their minds? If so, this could explain why many females meander on a lek for extended periods of time before copulating. Also, what about inexperienced hens breeding for the first time?  As a rule, selecting a male capable of holding his ground in the center of the lek, where rivalry among contenders is greatest, is a good choice. Another option is to choose a male that older females find attractive, a phenomenon called mate choice copying.