Who Set the Moose Loose?

Trophic Interactions in the Greater Yellowstone Ecosystem

Author:	Kristina Hannam Department of Biology SUNY Geneseo hannam@geneseo.edu
Abstract:	This “clicker case” focuses on the food web of the riparian bird communities of the Greater Yellowstone ecosystemand how community structure and productivity may be influenced by top-down mechanisms, resulting in a trophic cascade. As students examine the food web and non-feeding interactions among the community members, they uncover the effects of herbivore densities on songbird populations and gain an appreciation for species interactions and impacts in a biological community. The case is presented in class using PowerPoint slides (~2.6MB) that are punctuated by multiple-choice questions which students answer using clickers, though the case could be adapted for use without these technologies. Designed for an introductory biology course taken primarily by freshmen and sophomores to fulfill a general education requirement, it could also be used in an introductory course for biology majors.
Objectives:	Understand how to construct a food web and how different feeding relationships are represented. Examine data and infer what it suggests about species interactions. Distinguish between top-down and bottom-up control of ecosystem productivity. Understand the importance of non-feeding relationships among species on species abundance. Understand the role of top predators in trophic cascades. Recognize human influence on community structure and energy flow.
Keywords:	Food web; trophic cascade; riparian; species interactions; moose; songbird; birds; willow tree; hawk; coyote; predator; biodiversity; Yellowstone; Grand Tetons
Topical Area:	N/A
Educational Level:	High school, Undergraduate lower division
Formats:	PDF, PowerPoint
Type/Method:	Clicker, Interrupted
Language:	English
Subject Headings:	Biology (General) Ecology Environmental Science
Date Posted:	04/07/10
Date Modified:	N/A
Copyright:	Copyright held by the National Center for Case Study Teaching in Science, University at Buffalo, State University of New York. Please see our usage guidelines, which outline our policy concerning permissible reproduction of this work.

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