GEOLOGIST

During its larval stage, a ruthless two-inch beetle called the water tiger injects its victims with a venom that dissolves muscle, and then extracts its dinner like a teen sucking chocolate shake through a straw. And it's not afraid to attack creatures much larger than itself. All this would be fine as long as it happened somewhere far away, like New Jersey. But this Coleopteran monster lives in a pond behind my house.

I know this because of Mac Donofrio, 41, a Montana naturalist who recently made a house call to educate me about the wilderness pulsing in my own backyard. Last fall, Donofrio launched Home Ground Inventory Services, a one-man operation that surveys the flora and fauna on private land.

Donofrio's business is the culmination of 20 years in the natural sciences. Ever since moving from Maryland to study geology at the University of Montana in 1978, he has excavated prehistoric sites in the northern Rockies, studied bald eagles in Glacier National Park, and most recently cataloged songbirds in Montana and Idaho. "My goal is to spend every waking minute outdoors," he says. "Except when it's 33 degrees and raining."

On a stroll around my 25-acre place with Donofrio, I learned more in two hours than in the entire ten years I've lived here. "See that?" he said, pointing to what I thought was a fat sparrow, but what is really a northern pygmy owl. Farther on, Donofrio tore a leaf from a two-foot weed. "Hounds-tongue. If your horses eat it, they could get sick."

Donofrio charges $150 for one of these informational nature walks, but for $20 an acre he will conduct an archaeological survey of a piece of land's human history, the best places to site a building, and the probability of a wildfire whisking across your property.He assembles his findings in a scrapbook, complete with a hand-drawn map and pressed plants arranged in plastic sleeves.It's an ambitious undertaking, even for a veteran naturalist like Donofrio, but his backyard start-up has already taught him a valuable lesson: Namely, when it comes to understanding the environment, he shouldn't be afraid to attack things much larger than himself. —BILL VAUGHN

PROFILE
All Naturalist

• The Work: Take your pick among a dozen rock-jock jobs, including seismology (dig trenches across California fault lines to find signs of tectonic shift) and digital mapping with the U.S. Geological Survey. Or work as a petroleum geologist, scouting for oil traces along the continental shelves.
• Time Outside: 80 percent for government researchers, 25 percent for academics, 10 percent for consultants and oil seekers.
• Payback: $25,000 as a rookie USGShire; $30,000-$50,000 as a private consultant; $100,000-plus as a full professor or Exxon explorer.
• Prerequisites: A B.S. in the geophysical sciences gets you started, but to rise in the ranks you need an advanced degree: Try the University of Chicago (773-702-8101; geosci.uchicago.edu).
• Networking: The Geological Society of America (303-447-2020; www.geosociety.org) offers a monthly bulletin of job leads.
• Peon to Pro: "At first, all the rocks look gray," says Dartmouth geologist Page Chamberlain, "After 20 years, you see hundreds of shades of gray."
• Drudge Factor: Hauling rocks.
• Outlook: Academia is tight, but private sector work follows the economy. When the world's reserves go down and the price of oil goes up, so will the demand for geologists.

MARINE BIOLOGIST

• The Work: Scuba diving to check the health of Caribbean reefs; buzzing above Baja Sur to tally migrating gray whales; scraping lobster larvae from the seafloor; negotiating humane fishing practices with Maine lobstermen; tagging Stellar sea lions in Alaska; serving as one of three federally appointed delegates on the Marine Mammal Commission; consulting for eco-tour companies and aquariums.
• Time Outside: 30 percent fieldwork, 70 percent hustling grants and teaching.
• Payback: $25,000-$33,000 for nonprofit and government work; $40,000-$80,000 for university professors and researchers; $60,000-plus for independent consultants.
• Prerequisites: Get your toes wet working for nonprofits, zoos, or aquariums (a B.S. in ecology or biology is your ticket). To secure high-paying research grants and prime teaching positions, you'll need an advanced degree. Check out the University of Alaska-Fairbanks (907-474-7289; www.sfos.uaf.edu:8000) and the University of Mary land (301-405-6938; www.mees.umd.edu).
• Networking: The American Society of Limnology and Oceanography hosts annual symposia and publishes a journal eight times a year (800-929-2756; www.aslo.org).
• Peon to Pro: Seven years in the trenches from B.S. to grant-winning Ph.D.
• Drudge Factor: It's not all bikinis and bare feet; there is sea lion scat to collect and rotting jellyfish to analyze. "I necropsy lots of corpses," says Kate Wynne, a marine mammal specialist at the University of Alaska. "And some of them are the smelliest dead things going."
• Outlook: You could sink or swim. Competition for whale and dolphin research dollars is intense, so consider focusing on little-studied algal blooms or invasive organisms like pfiesteria instead.

Photo: Bill Vaughn (top); Norbert Wu