If you're a bird, nesting season — the whole business of courting and mating and raising a family — often parallels the behavior of certain bipeds with opposable thumbs but no feathers. The house finches this spring reminded us of this when the males donned the brazen red plumage that says here I am, girls, as plain as a new tattoo in a singles bar.

If you're a bird, nesting season — the whole business of courting and mating and raising a family — often parallels the behavior of certain bipeds with opposable thumbs but no feathers. The house finches this spring reminded us of this when the males donned the brazen red plumage that says here I am, girls, as plain as a new tattoo in a singles bar.

In the feathered world, it's usually the males that put on the style. It's up to the females to warm to or reject the pitch. This is analogous to checking out a guy's new Armani suit or BMW. In both cases he's flaunting it to declare he's successful (a good provider).

The first move appears to be made by the male, but in fact it's often up to the female, who must make a show of availability ( just talking birds here). Say you are a female mallard, and you see the boys are back in town. Instead of lowering your lashes or crossing your legs or fumbling for a light, you stretch your neck out and swim with your head barely above water, just so.

Wanna dance? Many birds strut their stuff by extending and vibrating their wings. The male grouse struts his stuff in a formal dance. Western grebe couples dance by rising together out of the water and "rushing," or running along the surface.

Eagles, hawks and crows do a dangerous dance in which a bird "hooks up" feet with his partner, and the two plummet, whirling, to near death before releasing each other at the last instant, much like a tango.

If things are clicking, a time comes for the female to send the signal. Let's go back to Ms. Mallard. What you do is give a series of quick, staccato quacks and flick your beak sideways, back and down. Foreplay consists of you and your beau floating face to face and bobbing your heads up and down. Ooh-la-la.

Many birds are monogamous. It's a reasonable arrangement, since in birds as well as in humans there is an approximately equal number of individuals of each sex. And breaking up is hard to do, and life is short, and there are eggs to brood, and so on. Some birds (eagles, geese, swans, parrots) are officially monogamous for life but may fool around. Others, such as house wrens, are serial monogamists that have one partner at a time, one after another, like Liz Taylor.

Male marsh wrens, red-winged blackbirds and indigo buntings that are rich and powerful enough (have good territories) practice polygyny, the taking of multiple mates in the manner of biblical Hebrews and Texas Mormons.

Then there's polyandry. If you're a female spotted sandpiper, the more of your sisters you can beat up, and the more eggs you can lay, the more "husband" sandpipers you get to have. In the sequential polyandry practiced by some phalaropes and jacanas, she mates with a male, leaves him to incubate the eggs and runs off with another male (honey, keep an eye on the kids, heh heh).

Still other birds, including some hummingbirds, have a Bill Clinton gene in which males see the act of genetic donorship as the perfect end of a beautiful relationship.

Gulls, terns, geese, swans, parakeets, ostriches and other birds sometimes form gay couples, even adopting eggs and raising broods. You don't have to be an ornithologist to see this. Check out Harry and Pepper, a gay Magellanic penguin couple at the San Francisco Zoo. The guys nest together on the north side of Penguin Island. Nor are they the first male couple there. A retired zoo worker said the male-male penguin couples seem happy. And they always have the most tastefully decorated burrows.