Science Vignette: Not Fenced In

By: Colbie Bell

Imaging you are being pulled along by a snowmobile in the cold expanse of Canada’s arctic. The temperature is warming up, it’s only about –20° C today, but it doesn’t seem that cold because the air is quite dry and you’re bundled up inside layer upon layer of winter clothes. You have just finished another day of tagging and reporting on rabbits. The snowmobile and the sound of the snow passing underneath the sled are the only sounds that you hear. Suddenly, the driver yells out "Hold on guys," as he attempts to jump a crack in the ice. You’re not worried, since the weather has warmed and spring break-up began, the team has crossed dozens of cracks like this one in the last week. The sled jumps forward as the driver accelerates to gain the speed necessary to jump the crack. Luckily the snowmobile clears the jump and makes it across. Unfortunately for you, the sled does not and falls into the lake. What would you do?

Charles Krebs had this very same experience on a research trip while crossing a lake in the South West Yukon Territory. Krebs was observed to be treading water with one hand and holding on to the data with the other yelling, "Save the data! Save the data!"

Charles Krebs is an ecologist and considers the great outdoors as his office and animals as his subject of study. His earliest recollection of his interest in nature is that of growing up in small town Illinois and listening to his grandfather tell of tales of wilderness adventures during their fishing trips. At the age of eight, Charles was sure that he wanted to be a forest ranger and to further that goal began reading books about the study of ecology. During his teens he worked for a St. Louis fur trading company that harvested seals in the Berring Sea. Perhaps it was due to the influence of these summer trips that Charles Krebs developed attraction to Canada’s arctic. Krebs went on to get his B.Sc. in Minnesota, before moving to Vancouver to complete both his M.A. and Ph.D. at the University of British Columbia. Since then he has written many research papers as well as the textbook "Ecology" published by Harper-Collins, which is used worldwide to teach courses in ecology and is now in its fifth edition.

As an ecologist, Krebs has spent the last forty-four years of his life trying to figure out why lemmings and other small Northern mammals undergo population crashes every four to ten years. The difficulty in studying animals and ecological processes lies in the fact that the collection of data takes so long. In forty-four years the only thing that Krebs is quite sure of is that contrary to the myth, lemmings do not suddenly develop the urge to jump off cliffs. The ability to keep track of wild animal in their natural habitats also makes it difficult to collect accurate data. In light of this, Krebs decided to fence in a pasture the size of a football field to observe the effects of different variables on a population of voles. It was his goal to provide a reason that would explain why population levels in voles and other small mammals steadily rise and then crash every four to ten years. A logical assumption was that the food supply for an area could be one reason for the observed population crashes. However, the population crashes were still observed even when the voles had access to an unlimited food supply. The population levels of predators was the next assumption to be tested, and was also ruled out as an explanation of cyclic population crashes. Krebs current belief is that this " fence effect" may be due to social behavior among voles. It’s been observed that as crowding occurs many mothers will go out and kill the babies in neighboring nests. However it should be noted that even after forty-four years of study that Krebs himself admits the fence effect is still only a theory.

Questions

Would you risk your life to save data? Can you think of situation in which you would?

Often labs are under pressure to come up with data and results quickly and accurately to improve some aspect of human life. Is this possible when studying ecological processes?

Some people see no reason to be studying animal species if the research does not benefit mankind directly. Proverb: "The flutter of a butterfly can cause an enormous clash across the globe."

What does this statement mean?

What can we say about the nature of ecology?

Resources

http://www.science.ca./scientists/scientistprofile.php?pID=11

© Colbie Bell.  Reprinted with permission from Colbie Bell.  All rights reserved.