Charles J. Krebs

Zoology, Animals, Physiology, Metabolism

Famous for writing Ecology: The Experimental Analysis of Distribution and Abundance (now in its fifth edition), a textbook used worldwide to teach ecology, and for his work on the Fence Effect.

"We should be conservative in the ways we deal with natural systems."

Charley Krebs sits at the back of the sled, tired and happy to be pulled along by the noisy snowmobile. Its high-pitched whine breaks the serenity of the frozen lake in Canada’s North. But Krebs loves it, the crisp cold, the wide-open whiteness. The wind sprays snow in his face as the snowmobile plows through another drift.

Krebs thinks about the morning as the sled swooshes along over bumps and cracks in the ice. With him are four ecology students from the University of British Columbia, two riding in front of him on the sled loaded with research equipment, two up front on the snowmobile. They are returning from a six-hour session of tagging snowshoe hares on a remote island in Kluane Lake in the southwest Yukon Territory. Working in teams, they have just finished checking live-hare traps placed throughout the island. They have removed many hares from the traps, taken notes on weight, sex and health and clipped id tags on their ears before letting them go. They have piles of notebooks to show for their work.

Krebs is satisfied. He’s thinking about how all this new information will fit into a paper he’s working on, when suddenly the student driving the snowmobile yells, “Hold on, guys!” and revs the engine to jump across a crack in the ice. It’s early May 1980. The lake is starting to break up with the spring thaw and they have crossed a few cracks already. The snowmobile makes it across, but it opens the crack too much. Before they know it, the sled, the equipment and three people are sinking fast in icy water. It doesn’t help that they’re all wearing winter parkas and heavy snow boots. Krebs treads water with one hand and holds the bundle of notebooks up with the other, yelling, “Save the data! Save the data!”

They did save the data in the notebooks, and themselves, fortunately. But his students never let Krebs forget that day. Data are hard to collect when you are a wildlife biologist like Krebs. He doesn’t work in a laboratory. His lab is the great outdoors. Since animal life cycles take years, you need decades of observation and data collection to understand a particular animal.

One of Krebs’ students tells a similar story. Once, with a different group of students, Krebs became trapped on an island in Kluane Lake. They had been flown in for the annual hare-counting and tagging session, but weather conditions became so bad that no plane could return to pick them up when they were done. The stormy weather went on and on. After they had been there two weeks longer than planned, the food ran out and the students suggested they eat some of the hares. Krebs refused, because the hares were his experimental subjects. The students were frustrated. They had all these traps and there were plenty of animals. Were they going to starve to death for the benefit of science? After a few more days, when people were getting really ravenous, Krebs finally relented and said they could catch and eat hares — but only if they didn’t have ear tags.

As a young scientist ...

Charles “Charley” Krebs grew up in a small Illinois town near St. Louis, across the state line in Missouri. He remembers as a kid fishing for catfish in local rivers with his grandfather. Charley admired his grandfather and his tales of natural adventures and wildlife. In particular Krebs was drawn to the Canadian Arctic. At eight years of age he wanted to be a forest ranger. Even then, he was reading books about basic ecology and the science of wild animals. He was fascinated by the big mysteries of the North — for instance, did lemmings really commit mass suicide by jumping off cliffs?

All through his high school years, Krebs had an unusual summer job. He worked for a St. Louis fur-trading company harvesting seals in the Bering Sea. Each summer he travelled by train for three days to Seattle, then by boat for seven days up the west coast of Canada to the northern islands. Krebs was curious about all the wildlife on the islands.

After getting his bachelor of science (BSc) degree, Krebs moved to Vancouver to study at the University of British Columbia with Dennis Chitty, who was (and still is) the world expert on lemmings. Krebs obtained a master of arts (MA) and a doctorate (PhD) in zoology, then after a two-year fellowship at Berkeley, California, he went back east to teach zoology at Indiana University. In 1970 Krebs returned to Vancouver and he has been there ever since as a professor of zoology at UBC.

In 2002 Krebs retired from teaching and began spending part of the winter working with the Rodent Research Group at the Commonwealth Scientific and Industrial Research Organisation in Canberra, Australia, to help them figure out why house mice in Australia reach very high populations at irregular intervals and cause extensive damage to grain crops. He also continues to work on snowshoe hares and other animals of the boreal forest in southwestern Yukon, Canada.

Krebs’ textbook, Ecology, is the standard teaching text for ecology courses worldwide. His interests have become a family affair. His wife is a research associate in ecology at UBC and often goes on field trips with him. His son works for the B. C. Ministry of the Environment, and his daughter is an expert on birds.

The Science