Bachelor pad: Vogelkop bower bird (Amblyornis inornatus). (Animal Architects).

Male Vogelkop bower birds could give human males a few lessons on wooing chicks. These clever New Guinean birds are real romantics. They build and decorate elaborate "bachelor pads," called bowers, solely as places to entertain female bower birds. When the ladies come calling, the male birds sing and proudly display the neatly prepared decorations, says Gerald Borgia, a biology professor at the University of Maryland.

Of the 19 species of bower birds, 15 are builders. Brown Vogelkops, weighing in at only 156 grams (5.5 ounces), weave twigs and sticks around a central pole until they've created a small hut. Their bowers usually feature a single doorway framed by a perfect arch. "Without the arch, the weight of the roof would cause the doorway to sag and fall in," says Eric Nelson, a Boston-based architect. "That could make the entire hut collapse."

Like the giant 63-story Gateway Arch in St. Louis, a Vogelkop's arched doorway is stable because the compressive (pushing) and tensile (pulling) forces that act on it are in equilibrium (balance).

Architects use a complex mathematical formula to calculate the exact size and shape of arched openings in buildings. Vogelkops, however, can't do math. Instinct tells them to build bowers, but they have to practice to get them right. Young birds often make messy, poorly decorated bowers; older birds have the skill to build more elegant homes. Building a bower may take as long as a few weeks, Borgia says. Once the process is complete, the birds "carpet" the entrance with moss and decorate it with thousands of colorful objects like orange flowers, yellow leaves, blue fruits, and red berries.

Borgia and Al Uy, a biologist at the San Francisco State University, used video cameras to discover that male Vogelkops with large, tidy bowers decorated with bright blue ornaments attract the most females. Hint to the guys: Maybe it's time to renovate your rooms.

HOUSE OF STYLE: Male bower birds scour the forest for colorful knick-knacks--purple wild tobacco blossoms, blue parrot feathers, white snail shells--to carpet the entranceways to their elaborately built huts, The bright colors help lure mates.

BUILT TOUGH: The Gateway Arch soars 630 ft (192 m) over the Mississippi River in St. Louis. Bower birds, like humans, build arches to keep structures stable.