Once you come to know vultures it's easy to understand why they get such a bad press.

Until this spring my only close acquaintance with the creatures was once when a turkey vulture flew into the grill of my van; I had to chase the terribly torn bird into a brierpatch and wring its neck.

Lately I have been given the privilege of frequenting a wild place in Southern Maryland, and on that place is a tumbledown cabin and in that cabin some black vultures are raising a couple of chicks.

The shack is on the path that leads into the heart of the property, and an adult bird is nearly always sitting in the window. If anyone stops, or even pauses, it flies up to a nearby tree and marches in place on a branch, nervously lifting one foot and then the other, until the intruder goes away.

The landowners wouldn't disturb a nesting bird even if it weren't against the law. They have abandoned the clearing around the shack to the birds, although they had planned to do some planting there this year. But I was tempted by the chance to get a close look at the young of a species normally seen only as a speck in the sky, especially of a bird that has only recently become fairly common in this region. I finally succumbed in late spring, when the chicks were sure to be fair good size.

Better I should have passed by. The first thing that happened when I entered the shack was hissing and growling so fierce and loud I jumped and hit my head on a beam. After the ringing stopped and my eyes had adjusted to the gloom I saw the pullet-sized birds huddled in one corner.

For reasons known only to herself Mother Nature has made most baby animals cute. In human children that has obvious evolutionary value, but "lower" animals are not believed to make esthetic judgments. Peahens presumably pick the prettiest peacock because the rascal's tail pattern triggers an instinctive reaction rather than an appreciation of line, form and color.

Be that as it may, Herself has made baby black vultures ugly. That is unwarranted, anthropocentric, dumb thing to say, since the point is not how they strike a human but how the parent birds react. Still, hoo boy.

The little darlings flapped their downy wings, stretched their oversized beaks forward and vomited at me in unison. I have smelled some ripe things in this life, but twice-regurgitated carrion -- the parent birds predigest the food -- was a new high.

They followed up the volley with a stifflegged charge. I fled, not wishing to know whether they had any more tricks.

"Sounds like a pretty standard vulture encounter," said raptor biologist Mark Fuller of Paxtuxent National Wildlife Research Center, whom I called to inquire about the beasts. "Hiss, growl, grunt, vomit, nip at you. We've done studies of caged vultures, and every time we'd go in to tend them or measure them we'd get dumped on."

Like 'em or not, it is Fuller's duty, and the duty of the rest of us, to do what we can to learn more about every species, the better to guage our stewardship of the planet and its living things. But black vultures are not cooperating. normally Patuxent would send someone out to band such birds, because surprisingly little is known about them. But "there is a prohibition against banding black vultures," he said.

"How come?"

"Well, you see, they defecate on their legs, and the stuff will build up around a band and cause sores."

"Why on earth do they do that?"

We think it helps cool their bodies by evaporation. But we can't prove it."

Since then I have kept my distance from the shack, where the chicks are no doubt steadily growing bigger and uglier. A parent bird is always around, inscrutable as ever.

And I have come to realize that the vulture's form and habits can only be considered beautiful by the rule that form follows function. It's a messy and valuable service they perform, cleaning up a landscape that otherwise would be littered with carrion.

Since their diet is going to make them reek anyway, they probably excrete on themselves just to increase the stink: It keeps away hawks and raccoons and foxes and nosy people.