With plumage of intense and other-worldly colors, deployable regal crests, and behavior that ranges from coy to maniacal, parrots have little trouble attracting our attention. But what traits fare best for these birds when their goal is inspiring love in potential parrot mates? Is a parrot sexy in the eyes of other parrots because it is a good provider, attentive, talented, or beautiful?

Of the parrots’ many qualities, colorful plumage is surely its most spectacular: blue and gold; red and green; blue, yellow, green, orange, red. These brilliant colors are not just splashed on these birds; they’ve soaked right through. It would seem that the fantastically gorgeous plumage of parrots would be obvious sexual attractants for mates. But when the would-be mate is flying the same colors, how sexy is that? In fact, 75 percent of parrots species are classified as sexually monomorphic, which means that males and female resemble each other physically.

It turns out that it’s not just color but the intensity of feather color that can be a turn-on to a prospective mate. Color intensity signals good health, immunity, parental care abilities, and breeding success — all key things to know if you’re in the market for a mate. In a study of wild Burrowing Parrots in Patagonia, Argentina, researchers found that the more intensely red the abdominal feathers on the parrots were, the better was their success in breeding.

Color intensity is a physical characteristic that we, as humans, can observe. But research shows that while male and females parrots of the same species look similar to us — they look different to each other. A parrot’s highly sensitive tetrachromatic avian eye can see the entire UV spectrum, while we only perceive light in the near-ultraviolet spectrum. So there’s a whole world of fluorescent color that a parrot’s eyes can visualize that our humans eyes just can’t.

Budgerigars have yellow fluorescent plumage on their crowns and cheeks. To determine if the fluorescent patches are used in courtship displays, researchers covered the crown feathers of male and female birds with sunscreen, limiting their ability to absorb UV light. Other male and female budgies spent more time courting “glowing” companions, ignoring those with dulled feathers. What the study showed was that the more a suitor glowed, the more alluring it was to a prospective budgie mate.

But don’t get the wrong idea: in the parrot world, mating is not based on looks alone. Some parrots appreciate “talent” or showmanship in a mate. In the kakapo’s mating system, the males go to a prominent location, such as a hilltop, and create a courtship area known as a lek, or a group of bowl-like indentations dug in the ground. When the males gather, they compete for the best spots, and then begin calling for the females. The male mating call is a very loud, low booming sound that can be heard for several miles. The booming goes on all night, every night, for as long as several months. At the same time, the males spread their wings and do a hopping dance. When females show up, they pick out the best boomers and hoppers for one blissful night of mating.

It should come as no surprise that music can woo a female. A good, strong singing voice in the bird world indicates good health, strong immunity, and a successful partner. But a study of budgerigars found that while a female appreciates vocal abilities, she actually prefers to mate with a male who sounds like her.

Glowing plumage, fancy moves, and a beautiful singing voice go a long way toward attracting a mate, but nothing says sexy to parrots like regurgitation. Though sometimes used as a reward for sex, many parrot species use food regurgitation as a part of the courtship ritual. Parrot couples exchange food, and thus information, on the quality of mate. A healthy amount of regurgitation tells the female that the courter can provide for her and her brood if she decides to choose him.

Those vibrant colors, beautiful voices, and fancy crests may all look like mere adornments to us, but to a parrot, they’re clues about a potential mate’s overall fitness, genetic superiority, and superior traits for survival. Just like with humans, in the parrot world, “sexy” takes many forms.

Female jumping spiders will attack and eat anything that moves. This often includes males who may be courting them. So, if a male falls short in convincing a female that he will be a good mate, he may become lunch. This is a compelling reason for males to work hard in perfecting their courtship dances.

In the mating game, it is not always “do or die,” but the penalties can be severe, and there is no single tried and true approach when it comes to the fascinating strategy of attracting a mate. Charles Darwin called it “sexual selection.” NATURE is calling it What Females Want and Males Will Do for love — a two-part miniseries about sexual selection.

What Females Want and Males Will Do explores the evolution of sexual strategies and what makes certain species winners and losers in the mating game. Courtship drives evolution by controlling whose genes are passed on to the next generation, and intense competition gives rise to a wide array of dazzling displays and impressive ornamentation.

From spiders that dance and monkeys that drum in the name of love, to female geladas that seek male partners with hot, red chest patches — this program about sexual selection explores the unique behaviors and special adaptations that determine how animals pick their mates, and how these selections affect future generations. In some species, the normal rules of mating are turned on their head, such as the feisty female topi antelope champing at the bit to have sex with an aloof male or bonobo males practicing free love.

Scientists around the world are making amazing new discoveries about the complex nature of courtship and competition throughout the animal kingdom. It’s sexual education that takes us way beyond the “birds and the bees.”

Part Two: What Males Will Do — Apparently, there is nothing a male will not do for the right to mate with a female — dance, sing, fight, change body colors, illuminate, even agree to be eaten alive. There is often a surplus of males, and they are instinctively driven to compete in order to pass their genes to the next generation. But it takes two to tango. Now, scientists are learning to what extremes males will go in order to find that dance partner.

To order a copy of What Females Want and Males Will Do, please visit the NATURE Shop.

Online content for What Males Will Do was originally posted April 2008.