MADISON, Wis. -- The duck was dead on arrival.
Packed in a plastic foam case with blocks of synthetic blue ice, the corpse came from Maryland as cold and dead as a duck could be.
One cool "canard" -- but what did in the duck? Who was the culprit in this mallard murder?
That was the answer that Christopher Franson sought as he leaned over the carcass, which lay on a stainless-steel table, under a bank of fluorescent lights.
Drawing a large knife over a sharpening steel, Mr. Franson prepared to carve the bird.
Mr. Franson is the chief laboratory diagnostician at the National TC Wildlife Health Research Center, a federal facility dedicated to analyzing and curing wildlife diseases -- which all too often man has a hand in causing.
State and federal wildlife agencies throughout the nation send their baffling cases to be examined by the Wisconsin lab. The Maryland duck, for example, had puzzled state Department of Agriculture staffers, who found it in a pond outside of Baltimore.
Working deftly with scissors and scalpel, Mr. Franson opened the duck and nipped and cut at its organs. He dropped samples of tissues into formaldehyde for laboratory analysis.
"Finding out what has killed a particular animal is a tricky business," he said. "Sometimes we can spend two or three weeks trying one thing or another and still never find out."
It may seem that disease in the wild is just a part of nature's balance, hardly needing special attention. But that is no longer the case.
"We've created situations where man has influenced the transmission of disease," said Milton Friend, director of the health center.
Because of the growth of domestic feedlots and poultry houses and the transport of all kinds of animals around the world, there are many more sources of diseases that can spread to the wild, he said.
Besides, there isn't as much "wild" as there used to be. "Wildlife has been forced into refuges and parks," Mr. Friend said. "We've lost so much habitat that we've changed the system, so we see infectious diseases which had never been a big issue become a major concern."
Pox, poisons and a host of other wildlife health problems keep flowing into the center, which was created in 1973 after an outbreak of duck plague. The plague, a herpes virus that came to the United States from the Netherlands, killed 40,000 ducks in the Lake Andes National Wildlife Refuge in South Dakota.
"It is these large-scale, dramatic incidents that are not natural occurrences," said Mr. Friend.
"We don't have very much of a natural environment left," he said. "We've polluted, we've altered it. . . . Disease is another expression of the problem."
Louis Sileo, a center research scientist who has studied problems as diverse as avian malaria in Hawaii and lead poisoning in American bald eagles, said, "We imbalanced things so much, we facilitated transmission of the disease.
"So," he said, "it is reasonable to expect that we try to right things where we can."
Before animals can be treated, someone has to figure out what ails them, and that usually happens in the center's basement dissecting room and the laboratories above it.
In the case of the Maryland mallard, Mr. Franson continued to methodically probe and search. "It isn't apparent," he finally said. "We've got a lot of pieces of this duck going in different directions; maybe something will pan out."
Within a few days, a break in the case came from the microbiology lab. The culprit was avian botulism, a disease that has killed as many as 1 million birds in a single year and as many as 50,000 animals in a single outbreak.
"It is a major killer of waterfowl," Mr. Friend said, "and it is an environmental disease, whose causative agent is in the soil.
"You must have certain environmental conditions before the disease occurs," he said. "But we are still trying to figure that out."
Maryland Department of Agriculture officials said that the case was an isolated incident and that there was no widespread problem.