Lek it or Not; where blokes show off

Nature has come up with a wealth of ways to achieve the most pertinent end of all - ensuring that your genes are passed on to the next generation, and preferably to a greater extent than those of your neighbours. One of the most impressive of these mating systems, from a spectator's point of view, is the lek, where hopeful males gather to display in competition, with the prize-winners being chosen by selective females, who ensure his gene line will continue on, in combination with their own.

The word is from Swedish, and referred originally to the display areas and gatherings of various grouse species, where the males gather in dozens to show off their finery and make a lot of noise. (If this reminds you of certain social situations involving young human males, there may be a reason for that too...) In many leks - perhaps even most - most of the  females' selection process is done for them, with the most successful males taking up position in the centre of the display area. It is no coincidence that these positions are the safest, with predators inevitably drawn to the edges of the performance. It is certainly to the females' benefit not to have to travel far to compare the talent on offer, and for said talent to sort out their rankings for her to inspect. The benefit to successful males is clear, though the also-rans may miss out entirely.

In the case of the Cocks-of-the-Rock, two species of outlandishly attired South American cotingas, the prize positions at the centre of the lek are determined by a series of one-on-one display contests between males, with winners edging ever closer to the middle. 

Andean Cocks-of-the-Rock Rupicola peruvianus, San Pedro area, southern Peru.
These brilliant colours come at a cost, as the carotenoids can only be obtained from fruits, then converted, by expenditure of much energy. More about this here.
Further, when a female (below) arrives, a frenzy of flapping and harsh calling erupts, again expending energy. They can ill afford to leave the lek to feed while others are present, lest they lose their spot.

Andean Cock-of-the-Rock female, Aguas Calientes, Peru.
She has no need to spend lavishly on gorgeous attire.

Another cotinga which forms leks is very familiar to movie-goers, even if they don't realise it. The startlingly loud call was used in every Tarzan movie, and most movies since then that featured rainforests, regardless of the continent! You can hear a selection of their calls here; I'd recommend the second and third ones as being pretty typical. Again such huge calls are at great cost, which is the point of the exercise - he is telling the world how strong he is, and what an appropriate father he'd be.

Screaming Piha male Lipaugus vociferans - love that species name! - Yasuni NP, Ecuador.
Here the display is purely aural, so no sartorial extravagance is required.

Still in South America, many of the hermit group of hummingbirds also engage in lekking, albeit not quite so spectacularly as cocks-of-the-rock or pihas. Males gather together, in dozens sometimes, in traditional lek sites, singing and tail waggling when a female approaches. Both of the species illustrated below are known to form leks.

White-whiskered Hermit Phaethornis yaruqui, Mindo Valley, north-west Ecuador.

Great-billed Hermit Phaethornis malaris, Yasuni NP, Ecuadorean Amazon.
Deep in the shadows of the rainforest floor is not a good place for clear photos - sorry!

Some African antelopes also practise lekking, though it seems that for them this is only one strategy. In species including Uganda Kob and Topi, some males form a traditional territory with good resources and try to attract females to it, while others form leks on relatively bare areas - of little other value - and fight to attain the coveted central positions. Because of the lack of resources males cannot maintain their position in the lek for very long. Females visit regularly, and make for the centrally located males; they will fight other females for the privilege of mating with these desirable males, especially in Topi where the females are only receptive for one day a year! ('Topi' are now regarded as comprising several species of the genus Damaliscus.)

Korrigum female and male Damaliscus korrigum, Waza NP, northern Cameroon.
Previously regarded as a sub-species of Topi or Tsessebe.

Uganda Kob male Kobus thomasi, Murchison Falls National Park, Uganda.
He is lekking, in typically sparse grassland, unattractive as a permanent territory.
(And if were prone to anthropomorphism, I might suggest he is looking very pleased with his position of honour on the Ugandan coat of arms.)

In the 1990s Galapagos Marine Iguanas Amblyrhynchus cristatus became the first reptile to be added to the list of 'lekkers'; in summer males gather on lava platforms to display and attract females.

Male Marine Iguanas, Isla Espanola, Galapagos.

Male frogs gather to call competitively, as do cicadas; many butterfly species indulge in 'hilltopping' where males compete for the sites closest to the top of a hill, where they display for females. All these are forms of lekking.

Macleay's Swllowtail Graphium macleayanum, a species which forms leks over mountain tops in Namadgi National Park high above Canberra.

Then there is a form of lekking known as 'exploded lekking', where the displaying males are far apart, but compete by loud calling. The most-cited of these is the wonderful but sadly critically endangered flightless New Zealand parrot the Kakapo which emits far-carrying booms - all night for up to four months, at great cost. Another apparent example is the Australian Musk Duck Biziura lobata, which splashes loudly and whistles and grunts, being audible and visible from far across the water.

Musk Duck male, south of Canberra.

I hope you've found this of some interest - at worst I've had fun writing it!

I'm off for a few days out of town over Christmas, but will be back soon with more offerings for your delektation.

BACK ON TUESDAY 31 DECEMBER