After rubbing snouts with his girlfriend and showing off his dance moves, the male poison-dart frog let loose a mating call that made his bright yellow-and-black underbelly pulsate.

Even though he and the object of his desire each weigh less than an ounce and are a mere inch or so long, the frog's alluring trill filled the humid air in a small renovated barn in Ellicott City.

"Poison-dart frogs are very social creatures," said Sean Stewart of the pair, whose courtship rituals will be repeated by other amphibious couples living inside the 100 clear plastic terrariums at Herpetologic, the frog and snake "farm" he owns.

"That quality, combined with their coloration and beauty, makes dart frogs the best pets," he said. And they aren't toxic when raised in captivity - another bonus.

Corey Wickliffe, who works part time for Stewart, said the frogs' public display of affection is just the beginning.

"They're at the point now where she's given him her phone number," she said, playfully describing the 2-year-old creatures' budding romance. "They're just in the first stages of mating."

Breeding is the name of the game at the facility that supplies a 10-year-old online business, which is an outgrowth of Stewart's longtime passion for amphibians and reptiles that dates to his childhood in Columbia.

"The county was more rural when I was growing up as a typical boy who liked frogs and snakes and spent a lot of time outside," recalled Stewart, now 39.

He started collecting poison-dart frogs when he was 14 and began selling them at age 21, nearly a decade before switching to Internet sales.

The other "merchandise" offered through Stewart's Web site is housed in the building's basement, where more than three dozen green tree pythons drape themselves around fake branches inside heated enclosures. Despite their name, the popular snakes come in various color combinations, such as blue and white or green and yellow.

Very specific rules apply to tending the pythons' homes and diet as well; each cage has its own thermostat and mice are on the menu every two to four weeks.

Over the years, Stewart has become one of the go-to guys for private collectors, zoos and research institutions worldwide. With more than 25 years' experience dealing with husbandry and propagation of amphibians and reptiles, he's made a name for himself as a consultant and a supplier.

"Sean has the drive and the ambition for this work," said Ed White, a biologist at the National Zoological Park in Washington. "And he also has the skills - both learned and innate."

But that's only half of Stewart's story.

His "day job" is emergency room physician at Holy Cross Hospital in Silver Spring, where he works three 10- to 11-hour stints each week. The job is intense, he concedes, but each shift goes by quickly, and his condensed schedule frees him up to oversee Herpetologic.

Stewart explained the dichotomy that is his life by saying he happened to be in the right place at the right time - twice.

While he was pursuing a zoology degree from the University of Maryland, College Park, he began an internship at the National Aquarium in Baltimore in 1992.

"One of the aquarium's priorities then was working with dart frogs, and they were the only institution worldwide doing it," said Stewart, who is married and a father of two.

After graduation in 1993, he accepted a fellowship with the National Institutes of Health in Bethesda. There he became acquainted with John Daly, the scientist whom Stewart described as "an icon in frog toxicology."

"There was this chain of coincidental events in my life" - a sequence that ended up shaping his future.

He went on to earn his medical degree from the University of Maryland in 2001, and then did a three-year residency at Maryland Shock Trauma Center, both of those decisions carefully planned.

But Stewart said he never dreamed of owning 1,000 frogs and a few dozen snakes, nor imagined himself conducting business around the globe. Helping him run his burgeoning enterprise are his mother, Barbara, and his younger brother, Christian.

There aren't too many countries the entrepreneur hasn't dealt with, and he has dispensed advice and sold inventory to zoos, aquariums and botanical gardens across the United States. He said he's presently working with two new clients, Sea World in San Diego and the Georgia Aquarium.

While some kids purchase frogs from him, 90 percent of Herpetologic's individual customers are serious hobbyists, he said.

Then there are the young professionals who buy pythons as an investment, Stewart said. One recent buyer spent $7,000 on reptiles and then turned that purchase into a $20,000 sale just two years later, a return that outperformed any real estate or stock deal, he said.

Smith said there is great interest right now in the types of snakes Stewart breeds.

"Sean's really into it, even though those snakes are prone to problems in breeding and hatching," he said. "This work attracts a cadre of folks who look at it as a mark of their skill, and Sean is exceptional."

Stewart admits to being a Type-A personality, always pushing himself and seeking new experiences. As if he weren't juggling enough, he also arranges tours for local elementary and middle-school science classes on occasion.

"This job is intriguing and challenging, and it's difficult to get bored," Stewart said. "One of the goals here is to sustain our passion in working with these amazing creatures."

Neighbors

Is there a noteworthy person or event in your neighborhood? Contact Neighbors columnist Janene Holzberg at jholzberg76@msn.com or 410-461-4150.