War of the sexes, 3

Choosy females

Although females behave less dramatically than males, they have a very crucial hand to play in the mating game. They are not, as usually portrayed, passive recipients of male lust, but are naturally cautious and highly discriminating when deciding with which to copulate. From their point of view, all males are different and, as every female wants only the very best possible specimen to father her offspring, she plays for time while assessing the quality of what is on offer.

Females therefore go shopping for sex and males must market themselves like animated billboards to attract a customer. Lavish ornamentation often means quality, because mediocre males cannot afford the luxury of ‘expensive’ displays. By weighing up the choice of mates and choosing only the chirpiest or flashiest partners, females act as wildly imaginative artists, capable of ‘creating’, through sexual selection, males which are as breathtakingly gorgeous as they are bizarre…

Among the amphibians, male frogs woo by trilling or croaking. Male anolid lizards erect brightly coloured dewlaps, while fish tend to flourish decorative fins. Most mammals have keen noses and accordingly use seductive odours to meet up with the opposite sex. Some insects stridulate—make a chirping or scraping sound, like grasshoppers—for sex, whereas others deploy potent scent to lure mates. Emperor moths can home in from 3 kilometres (2 miles) away by following a plume of perfume which acts as both an irresistible attractant and an aphrodisiac to members of the opposite sex; in web-building spiders, the males strum a tattoo on the silken threads which their partners perceive through their feet. Fireflies emit flashes of light, certain diurnal butterflies reflect patterns of ultra-violet and electric fish communicate with each other in the murky waters where they live by discharging pulses of electrical energy. In some species, the males advertise for sex in such extravagant manner as to defy imagination—and all because they must catch the eye of a discerning female.

The blue peafowl is the largest and most spectacular of the true pheasants. In full courtship mode the male is, without a doubt, one of the wonders of nature and an eloquent testament to the creative force of sexual selection. He is nothing less than an ostentatious sexual advertisement, proclaiming with strident voice and ornate plumage that he is the best source of sperm…

But sex is not the end of this affair. Peahens are remarkably possessive of the peacock with which they have mated and, although they need to be inseminated only once to have their eggs fertilized, each female tries to monopolize his attentions by being aggressive to other hens or by actively soliciting further copulations from the male if he starts to court another. By exhausting the male’s supply of sperm, the peahen attempts to prevent him passing on his desirable characteristics to the offspring of other peahens, which will inevitable compete with her own.
 
Bridal bowers

Some of the most extraordinary birds to be seen in Australia and New Guinea are the dozen or so bowerbirds which rate as the landscape artists of the avian world. The fact that most native mammalian predators in Australasia are nocturnal makes it possible for the males to spend the days displaying on courts close to or on the ground, which they meticulously prepare for the purpose of sex and seduction. As they eschew parental duties and the forest provides plenty of easily obtained food, the males are able to dedicate much of their year to building and decorating their bowers.

The hens behave like connoisseurs of art, awarding their sexual favours to the owners whose works impress the most. Depending upon the species, the male bowerbirds build structures ranging from the simple avenues of twigs—like the dazzling yellow and black regent bowerbird’s—to more elaborate ones which the owners embellish with all manner of bright objects; the cock satin bowerbird even daubs the walls of his bower with ‘paint’ derived from strongly coloured berries crushed in his break.

chapter-bBut there are as nothing compared to the achievements of three gardener bowerbirds—Macgregor’s, the striped and the Vogelkop—which practise their art deep in the forests of New Guinea. These mostly brown birds, the size of a starling, are master builders, constructing out of interlocking twigs maypole-like towers up to 3 metres (10 feet) in height, and huts resembling tepees supported by internal columns with passageways connecting inner chambers. Furthermore, The birds landscape their buildings with carefully tended forecourts on which all kinds of eye-catching treasures are displayed. In the case of Macgregor’s bowerbirds, and possibly the others, decorative fruit is brought into the bower and the cache doubles up as a snack bar, allowing the cock bird to spend more time on site advertising for hens.

Although they all construct amazing bowers, Vogelkop bowerbirds—from the mountains of the western tip of Irian Jaya—produce the most extravagant exhibitions of landscape art. The male’s arena is 5-6 metres (16-20 feet) across, with his astonishing bower in the centre. This is constructed around a sapling and is completely covered in by a thatched roof which is supported internally by several pillars.

In front of the entrance is the garden, on which is meticulously arranged a variety of pretty or conspicuous objects gathered from the surrounding forest—a number of faded yellow leaves laid out in a pattern, a heap of brightly coloured berries, the iridescent wing-cases of a certain kind of beetle and fresh flowers which are changed daily before they wilt. The industry involved in maintaining such an arena must be phenomenal and yet the investment will be well worth while if the hens are impressed and allow the male to father their next broods.
 
Dazzling duets

Scientists working in the sweltering forests of Costa Rica claim to have discovered that female long-tailed manakins may be the fussiest females in the animal kingdom. Cock long-tailed manakins are forced to be really high-pressure salesmen; they will be chosen to mate on the basis of how well they sing in tune, shine on the dance floor and excel themselves in an extraordinary test of stamina.

These sparrow-sized birds belong to a family of forty or so exotic species which are confined mostly to South America. Second only to the incomparable humming-birds, male manakins are dazzling feathered jewels, their plumage sparkling with sky blues, brilliant reds and yellows set against the deepest velvet black. Some of their wing and tail feathers are modified for producing a variety of instrumental sounds which supplement the curious vocalizations the male utters to draw the attention of the hens.

The courtship displays are nothing short of virtuoso performances, choreographed into series of pivoting movements, mincing steps, jumps, somersaults and butterfly flights. Although the details vary from species to species, the acrobatic displays of the manakins rival those of any bird of paradise and are equally difficult to observe because they take place either in the forest canopy pr in deep cover near ground level…

Once she has made her choice, the top male signals his junior partner to make himself scarce. He then performs a solo dance in front of his admirer and then, in a flash, mounts and inseminates her. The reward for the junior male may come later—he may inherit the stage when the more experienced bird dies or vanishes, but he may have a long time to wait, because long-tailed manakins live for about fifteen years.

Almost all the hen manakins end up mating with but a handful of males. In one area with about eighty cocks, just five of them accounted for over 90 per cent of the matings over a course of ten years. So it pays to be a senior male manakins in a top performing team because such a bird is likely to be chosen by as many as fifty or sixty hens a year.

However, the cost of that achievement is considerable. It has been estimated that during his apprenticeship as a junior partner, a male will utter about 3 million ‘to-le-do’ calls and spend about 1000 hours perfecting his cartwheel routine before standing a chance of graduating to the status of a senior male.

Published in: on October 26, 2016 at 11:36 am  Comments (1)  
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  1. Reblogged this on Kerberos616.


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