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Top of the class

The truth about food chain isn't always pretty

Fourth-graders at J.D. Floyd learn by examining what owls eat - and what they can't keep down.

By MATHEW WASSERMAN
Published December 15, 2005

SPRING HILL - The easiest way to find out what something ate is to analyze what came out of it. That may seem like a disgusting concept, but it's a scientific truth.

It's easier for some animals than others. For example, owls can't chew their food, so they swallow everything whole. About every 24 hours they regurgitate a pellet about the size of a human thumb containing everything that was indigestible.

Last week, science resource teacher Patrick Kirchman's fourth-grade class at J.D. Floyd Elementary School got to sift through the owl indigestibles and discover exactly what the owls ate and which parts couldn't stay down.

"About 95 percent of what the students found were mice bones," said Kirchman. "I think every student found at least one skeleton, and some found three or four."

The students used dissecting forceps and probes to examine the pellets. When they found intact bones, they glued them onto papers that featured diagrams of the four most popular types of owl prey: mice, moles, birds and shrews.

"It was neat to find the actual bones of the animals and match them up with the picture," said fourth-grader Jaclyn Benko, 10. "I think some of the kids thought it was nasty, but I didn't."

For the students who did think it was gross, Kirchman said excitement replaced that feeling quickly after each student went to work on his individual owl pellets, although some students developed a combination of the two feelings.

The pellets were harvested in New England from common barn owls. Each pellet is about a day's worth of food for an owl, which normally equals about six mice. The point of the class' owl unit was to explain the food chain and natural relationship between mice, owls and people.

As owls perch at the top of the food chain, mice and the other rodents and birds that owls eat face life as links in the chain. However the owls now face a somewhat unnatural predator in the form of land developers who are destroying their homes to make way for houses and businesses.

"The average female mouse produces about 40 mice per year," said Kirchman. "If there are no owls to eat the mice, then the mouse population becomes overgrown and they start destroying crops and vegetation. There's a balance that shouldn't be interfered with because there is an interdependence between things like owls and mice and humans."

As Kirchman explained this idea to his students, they created food webs to illustrate the point.

"It was interesting to find out what animals eat what things and how the whole chain goes through," Jaclyn said. "Each thing in life affects something else."

The mysterious cycle of life, discovered and explained through owl regurgitation.

"You need a hook to grab the students' attention so you can really teach them," Kirchman said. "This got their attention."

Mathew Wasserman can be reached at Mat65432@aol.com

[Last modified December 15, 2005, 00:33:15]