Five llamas or five pigs or three horses equal one "animal unit"?

They do in Fairfax County, where the Board of Supervisors voted this week to clarify livestock laws that restrict the owners of large lots to one animal unit per acre.

It's all based on the cow, see? Two cows equal one unit. Five sheep are one unit. So are five goats, three horses or five alpacas.

What if a Fairfax resident would like to keep a pig, a llama and a chicken?

"Work the fractions," said Lu Wright, assistant to the zoning administrator and chief of the county's zoning ordinance amendment section.

A pig is one-fifth of a unit, as is a llama, she said.

Chickens are harder to figure. "We have 'bird units,' " said Wright. "This is a concept similar to the animal unit, using the adult chicken as a base."

Thirty-two chickens are a bird unit. One chicken is roughly 1/32 of an animal unit.

Wright calculated for the pig, llama and chicken. "About 69/160 of an animal unit," she said.

And, therefore, permitted.

County officials developed animal unit measurements, which are based on how much land is required to support a head of cattle, in the 1970s after considerable public input. "I never heard from the chicken people," said Wright. "They were the one set of people I never heard from."

How about cicada units?

"Bite your tongue," said Wright. "I only have to worry about those every 17 years."

But the county developed honeybee guidelines; some bee owners were required to build "flight path barriers" so insects wouldn't buzz low over neighbors' yards.

"George thinks that's hysterical," said Wright, referring to Planning Commission Chairman George M. Lilly. "I keep trying to tell him that after adopting the code, I found flight path barriers in almost every code I picked up. They're even in the Hawaiian code."

Fairfax's animal unit formulas and hive restrictions worked fine, except that they caused some confusion.

"For example," said Wright, "the code had been misinterpreted by at least one of the zoning inspectors to mean that each individual hive had to have its own water source, so if you had five hives, the inspector thought it meant you had to have five water sources."

In an effort not to change the livestock and bee restrictions, but straighten them out, the Planning Commission held a May 20 hearing to consider an amendment.

Here's a verbatim excerpt:

Commissioner John H. Thillman: "Less than one burro is not an animal unit?"

Wright: "Less than what?"

Thillman: "One burro. Mule -- not mule, burro. You've got burros, B-U-R-R-O-S, burro. Less than one is not an animal unit?"

The commission approved a few wording changes, acknowleged the existence of alpacas and llamas in the county, and redefined buffalo as "bison (American buffalo)."

"Apparently, that's a definition type thing," said Lilly, who owns no personal animal units ("No, ma'am.")

The amendment then went to the Board of Supervisors, where it was approved Monday.

"Wasn't that fascinating?" asked Vice Chairman Martha V. Pennino, afterward. "Like, you can have two llamas and one swine in an animal unit."

She said she had never heard of "animal units" before and, in any case, hadn't possessed any since she was a girl in Gloucester, Mass., and drove her goat, Capricornus, around in the back of a station wagon.

Pennino also grew up with dogs. "Five Chihuahuas don't equal one St. Bernard, I can tell you."

She said one of the things that most surprised her was to learn of the growing popularity of llamas in Fairfax.

"Yeah," sighed Wright, remembering Monday's meeting. "They had to ping at me about llamas and alpacas, and how many did we have in the county, and were the herds escalating."

Said Pennino: "To me, a llama is like a small camel, and a camel is not a friendly beast."

She remembered the camel at the grand opening of the South Lakes Shopping Center near Reston. "That thing spit at me. It hissed. It stunk.

"I said, 'Hey, friend -- the feeling is mutual.' "