In addition to eating the fruits of chapils and other trees (along with the odd lizard, frog, or insect), male long-wattled umbrellabirds have one overriding preoccupation: sex. During the August-to-February mating season, groups of between five and fifteen males gather every morning and afternoon at special sites called leks, each of which typically covers about 4.5 acres. Most males stake out their own territories within a lek. Beginning in the predawn darkness, the males sit on their favored perches and bellow their moo calls out into the forest around them. As the day breaks, they begin to extend and retract their crests. They ruffle the feathers on their wattles and bob them up and down. They spread their wings out in a vulture-like pose and make a strange gurgling sound. They briskly beat their wings against their bodies, making a sound like the ears of a wet dog shaking its head dry. Sometimes they pull small branches off their perching trees and beat them against the limbs or trunk. They spend hours each morning and afternoon in such elaborate displays, often nearly falling off their branches from the exertion.
Singin’, dancin’, lookin’ fine . . . the males are, of course, trying to impress females! For their part, female umbrellabirds spend most of their time away from leks, and rarely intermingle with males. But each year, when it comes time for a female to reproduce, she visits the leks to find a sire for her offspring. Each male wants to convince every visiting female to copulate with him, and not with the guy down the hill. But females don’t rush headlong into romance. They shop around, extensively.
At first, a female may pass close to a lek without entering, listening to the different males sing. After a day or two of that, she may visit a male that sounds particularly good to her. She flies in silently and perches ten or fifteen yards away. When he notices her, he kicks his efforts into overdrive and begins an energetic sequence of singing, head bobbing, wattle ruffling, wing spreading, and whatever else may occur to him. She sits on her perch, apparently absorbed in preening her feathers, but really all eyes and ears, as he fires up his one-man show.
If she’s making her first visit, she will invariably fly off after a few minutes, as quickly and quietly as she came. She will definitely drop in on many males, and perhaps several different leks, before picking a mate. Sometimes she’ll return to the same lek for several consecutive days. Sooner or later, however, she settles on one male and begins to spend more time on his turf. Whenever she is near, the male feels compelled to ruffle, fluff, gurgle, and moo, pulling out all the stops.
Finally, the moment arrives, and she flies over and perches about a foot away from him. He slowly works his way toward her until he is by her side. He pauses. Crest flared and wattle ruffled to the max, he moos once or twice, maybe throwing in a gurgle for good measure. He then performs what my assistants refer to as “the deal-closer”—the umbrellabird equivalent of dimming the lights and putting on some Barry White. He vigorously sways his head away from the female and then back toward her, causing his wattle to swing up around her neck and come to rest on her back, like a feather boa. Her eyelids lower at such an intimate embrace, and he seizes the moment, hovering up behind her on the wing to consummate their brief union. Although the courtship takes several days, the sexual act lasts just seconds. Before you can say “long-wattled umbrellabird,” the male is back by her side and she jolts back to attention, preens a bit perhaps, and then flies away without a backward look.
And that is the extent of their relationship. The female is now on her own. She flies back to her home area in the forest, sometimes a few miles away and proceeds with the business of nesting. My team and I haven’t been able to document whether she builds her nest before mating or after, or how long she can hold sperm before fertilizing her eggs. (Some female birds can store sperm for months before they use it.) Sometime after copulating, however, the female lays a single egg. She alone then incubates the egg; feeds, broods, and protects the chick until it leaves the nest; and continues to care for it until it can fend for itself, a few months later.
The male’s life, conversely, remains centered on the lek. For several months of the year he spends most of his time there, leaving only to eat. He will never see the nest where his offspring is raised, and most likely wouldn’t know his own son or daughter if they met beak to beak. Such deadbeat-dad behavior may not provide a good example of responsible parenting by human standards, but it is part and parcel of the lek mating system as practiced by many bird species.