New search
download case
  • Overview
  • Teaching Notes
  • Answer Key
  • Supplemental Materials
  • Videos
  • Comments/Replies

The Return of Canis lupus?


Parks Collins
Natural Science
Mitchell Community College


Although gray wolves once freely roamed North America, the gradual loss of their habitat from westward expansion and extermination programs led to their demise in the early 20th century. Many argue that predators such as wolves benefit a functioning ecosystem. In 1995, following years of extensive planning and controversy, wolves were brought from Canada and restored to Yellowstone National Park. This case study provides students with an opportunity to integrate various abstract ecological concepts (trophic cascades, keystone species, interspecific versus intraspecific interactions) with applied ecology as they learn about the wolf reintroduction debate and the conservation of an ecosystem. As part of their case work, students formulate and present a management plan. Originally designed for a college ecology course, this case has also been successfully used with both majors and non-majors in basic biology courses. Students will need some background knowledge of community and population structure within ecosystems.

  • Explain ecological concepts as they are set in the context of an ongoing controversy.
  • Differentiate between interspecific and intraspecific interactions.
  • Differentiate between density-dependent and density-independent factors as they relate to population size.
  • Define carrying capacity.
  • Understand how wolves are linked to a trophic cascade mechanism.
  • Understand why the wolf is considered a keystone species.
  • Analyze data sets.
  • Develop literature review skills.
  • Apply information from research and behavior to a management plan.
Keywords: Wolf; wolves; Canis lupus; animal behavior; trophic cascade; carrying capacity; interspecific competition; intraspecific competition; density-independent factors; density-dependent factors; keystone species; food web; community; Yellowstone National Park
Topical Area: Ethics, Regulatory issues
Educational Level: High school, Undergraduate lower division, Undergraduate upper division
Formats: PDF
Type/Method: Analysis/Issues, Discussion, Interrupted, Student Presentations
Language: English
Subject Headings: Ecology   Wildlife Management   Biology (General)  
Date Posted: 8/6/2013
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.

Teaching Notes

Case teaching notes are password-protected and access to them is limited to paid subscribed instructors. To become a paid subscriber, begin the process by registering here.

Teaching notes are intended to help teachers select and adopt a case. They typically include a summary of the case, teaching objectives, information about the intended audience, details about how the case may be taught, and a list of references and resources.

  Download Teaching Notes

Answer Key

Answer keys for the cases in our collection are password-protected and access to them is limited to paid subscribed instructors. To become a paid subscriber, begin the process by registering here.

  Get Answer Key

Supplemental Materials

The supplemental material below may be used in conjunction with this case.

  Click-and-Learn: Exploring Trophic Cascades hhmi/
Trophic cascades refer to impacts that reach beyond adjacent trophic levels. This interactive walks students through the classic example of sea otters in the kelp forest ecosystem off the west coast of North America. Students then apply their knowledge to predict responses and consequences of ecosystem changes in four other case studies. The case studies demonstrate how indirect effects mediated by changes in one species can broadly alter many aspects of community function. Produced by HHMI BioInteractive.


The following video(s) are recommended for use in association with this case study.

  Some Animals are More Equal than Others hhmi/
This short film opens with two questions: "So what determines how many species live in a given place? Or how many individuals of the species can live somewhere?" The research that provided answers to these questions was set in motion by key experiments by ecologists Robert Paine and James Estes. The film discusses Paine's starfish exclusion experiments on the coast of Washington state as well as Estes' and colleague John Palmisano's discovery that the kelp forest ecosystems of the North Pacific are regulated by the presence or absence of sea otters, which feed on sea urchins that consume kelp. These early studies were the inspiration for hundreds of investigations on other keystone species and trophic cascades, as well as ongoing studies into the regulation of population sizes and species numbers. Running time: 19:29 min. Produced by HHMI BioInteractive.

  Film Guide for "Some Animals are More Equal than Others" hhmi/
Film guide as well as instructor materials and a student quiz that complement the film "Some Animals Are More Equal Than Others: Trophic Cascades and Keystone Species." Produced by HHMI BioInteractive.

I was wanting to discuss with someone who had used this case study on a high school level and bounce some ideas off of you for direction with students on writing the management plan.

Jessica Labbe

Bremen High School

City State:
security code
Enter Security Code: