Large, introductory, nonmajors biology classes present challenges when trying to encourage class discussion to help reinforce important concepts. Lively in-class discussion involving hundreds of students is more successful when a relevant story told with passion is used to introduce a topic. In my courses, each semester begins with thorough treatment of the scientific method, followed by the multiple Darwinian theories of evolution. To reinforce these two important themes, the story of the ivory-billed woodpecker’s ecology, evolution, conservation, and probable extirpation has been effective in provoking class dialogue and reinforcing the two themes. Although I describe this approach as a large-class activity, it works well in courses of all sizes. In this article, I discuss teaching with storytelling and detail the use of the ivory-billed woodpecker story as a teaching tool.

Introduction

My annual responsibilities at the University of Kentucky have involved teaching five to six sections of two large, nonmajors introductory biology classes (Human Ecology and Basics of Biology) with enrollments ranging from 300 to 550 students per section. These large classes present various pedagogical challenges. For example, in-class, hands-on activities are extremely difficult to execute, to the point of not being realistic. One way around this dilemma was for my students to design experiments during class discussion that tested hypotheses (e.g., birds choke to death after eating wedding rice; see Krupa 2005) that I then carried out, reporting results back to the class each week. The wedding-rice activity lasted the semester and was extremely successful; however, it had limitations due to the amount of lecture time involved. I rely more on specific discussion-oriented topics lasting one or two lectures. Finding topics that provoke discussion is difficult, and I am constantly searching for new ones that work. I want these discussions to reinforce important, recently introduced themes.

One of the challenges of trying to provoke discussion in freshman classes is getting students in the mindset early in the semester that lively interactions are expected each time we meet. Unfortunately, discussion does not occur in many of our large science courses, and too many instructors discourage it. Consequently, many students find such interactions unusual and intimidating and need time to get used to this approach. Finding a topic that will capture students’ interest to the point of overcoming their inhibitions is my goal. Over the years, through trial and error, I have found topics that work. The formula that works best is to lead off with a topic about which I am passionate. The topic is delivered with my best storytelling skills. If I succeed in delivering the story, my students are primed to participate in the discussion.

Too often, I have watched educators focus their attention on improving content retention and active learning by incorporating technology, without considering other ways to ignite our students’ interest. Comments on the importance of igniting interest as a key part of education have surfaced over time. The phrase “education is the kindling of a flame, not the filling of a vessel” is attributed to Socrates (470–399 B.C.), although there is disagreement on whether he is responsible for these words. Plutarch (46–120 A.D.) is claimed to have said that “the mind is not a vessel to be filled but a fire to be kindled,” and Yeats (1865–1939) has been credited for similar words: “education is not the filling of a pail, but the lighting of a fire.” Regardless of who first compared good teaching to lighting a fire, I am ever mindful of these words, because they remind me that I need to develop teaching methods that will kindle excitement in my students. As a biology professor at the University of Kentucky (UK), I never forget the impact that past UK teachers have had by inspiring students. As UK alum John Scopes said, “Teachers rather than subject matter rekindled my interest in science” (Scopes & Presley, 1967). This expresses my primary goal. Telling a good story provokes lively discussion and, hopefully, thus lights the flame. This is a challenging goal when facing hundreds of freshmen, many of whom are less than enthusiastic about having to take a science course. I know that my course is often the last chance to convince these students that biology in particular (and science in general) is exciting.

Engendering excitement in large classes requires passion, effective storytelling, and extensive class discussion. Recently, Reece (2011) asked UK students in his freshman composition class, English 104, to write an essay profiling their best or worst teachers. Sadly, most chose to write about the worst. Three of the common shortcomings students saw in their teachers were a lack of knowledge of the subject, lack of passion for the subject, and unwillingness to engage in dialogue.

The great 19th-century teacher Louis Agassiz was adamant that educators only teach what they know extremely well. Agassiz felt that the best lectures involved topics the teachers were knowledgeable in and passionate about. I am not sure how one can exhibit passion for a topic without possessing extensive knowledge. Furthermore, passionate teachers are often great storytellers. Thomas Huxley, another great 19th-century biology teacher, was, like Agassiz, a great storyteller (Desmond, 1997). Huxley’s lecture “On a Piece of Chalk” stands as one of the best of all time (reprinted in Beebe, 1944). George Sutton, the 20th-century ornithologist, artist, and teacher, is noted for his exceptional storytelling skills as well (Jackson, 2007). Two of my most influential teachers (Ken Geluso, University of Nebraska Omaha; John Janovy, University of Nebraska–Lincoln) took classes with George Sutton as graduate students at the University of Oklahoma in the 1960s. Their teaching styles and skills of storytelling are reminiscent of Sutton’s and likely influenced by him. Even today, former Sutton students, now retired, talk often about Sutton the teacher. Clearly, like Agassiz and Huxley, Sutton’s knowledge, passion, and storytelling skills were what made him a great teacher and ignited passion in his students. If each of us profiled our best and most influential teachers, I venture to guess that most of these teachers exhibit Sutton’s attributes. The importance of these attributes as teaching tools and how to develop these skills is rarely a workshop topic, and yet storytelling is a method amenable to large-class teaching and advocated by inspirational biology teachers from Agassiz (Cooper, 1945; Krupa, 2000) to E. O. Wilson (2002).

Discussion of the use of storytelling in teaching is sporadic and mostly focused on K–12 education. Kieran Egan (1986) addressed this approach most thoroughly, and Joy Hakim (2002) provided an example of the story of the atom as a way to convey a scientific lesson to middle school students. An excellent discussion on teaching using storytelling is at the NCTE website, entitled “Guideline on Teaching Storytelling” (http://www.ncte.org/positions/statements/teachingstorytelling). Wiggins and McTighe (2006) briefly mentioned the power of storytelling, and Wilson (2002) detailed the power of storytelling for teaching science. In their nonmajors biology textbook, Shuster et al. (2012) employ this technique by using a historical story (in their Milestones in Biology sections) to introduce a topic. Clearly, storytelling is an approach that is ancient and obvious, yet overlooked by modern pedagogy. As a long-time devotee of this approach, I am convinced that my rapport with my students and their retention of the central lessons are maximized when I am most passionately engaged in relating my best stories.

It is curious that little pedagogical discussion has focused on how to develop and improve storytelling skills. This may be due to the belief that one is a good storyteller by nature and, thus, that developing this skill is not possible. I hope this is not the case. I listen carefully to excellent storytellers (e.g., Garrison Keillor delivering his “News from Lake Wobegon”) and use their techniques in delivering my lectures. I may be a storyteller by nature, but I still spend a considerable amount of time developing these skills.

I want students to think scientifically as well and to challenge my explanations by generating alternative hypotheses. It is imperative to use a story that will compel them to discuss, hypothesize, and challenge. Two themes run throughout my courses. The first is the scientific approach, which is introduced in week 1 of each semester. This introduction to the scientific approach begins with the definition of theory: a comprehensive explanation of some aspect of nature that is supported by a vast body of evidence that generates testable and falsifiable predictions (National Academy of Sciences & Institute of Medicine, 2008). Next, I differentiate theory from fact by defining fact: a scientific explanation that has been tested and confirmed so many times that there is no longer a compelling reason to keep testing it (National Academy of Sciences & Institute of Medicine, 2008). Thus, evolution is both theory and fact! Third, I define and explain strong inference and the multiple-hypothesis approach advocated by John Platt (1964) through his four steps: (1) Formulate a series of alternative hypotheses; (2) Set up a series of crucial experiments to test these hypotheses, each experiment able to rule out a particular hypothesis; (3) Carry out experiments in as clear-cut a manner as possible; and (4) Eliminate the hypotheses that failed step 3 and return to step 1. Although there are criticisms of Platt’s approach (discussed by Pigliucci, 2010) for being too simplistic, strong inference remains a valuable scientific approach that students should know.

Evolutionary theory is the second theme. It is introduced in the third week of the semester, covering the multiple Darwinian theories of evolution that are the foundation of biology. Too often, only natural selection and descent with modification are emphasized in introductory biology classes. Instead, I present the overlapping and interconnecting Darwinian theories as teased apart by Ernst Mayr (1991), and I go beyond Mayr by distinguishing descent with modification from descent from a common ancestor. These include (1) evolution as such, (2) gradualism (including the nuance of punctuated equilibrium), (3) descent with modification, (4) descent from a common ancestor, (5) multiplication of species, (6) natural selection, and (7) sexual selection. I emphasize that the first five theories are the patterns of evolution, whereas natural and sexual selection are Darwin’s mechanisms for how evolution occurs.

These two themes, the scientific method and evolutionary theory, are the foundation on which each course is built; moreover, they are the unifying threads that twine through the semester, binding the course together from beginning to end. Beginning in week 4 of the semester, I reinforce these themes and set the expectation that the course will involve extensive discussion and hypothesizing. For this, an especially captivating topic is needed to secure student interest. I have tried numerous topics over the years. The story of the ivory-billed woodpecker, one with which I am deeply familiar, has proved most effective. Below, I detail how the ivory-billed woodpecker provokes discussion and reinforces these class themes.

The Ivory-billed Woodpecker

The story of the ivory-billed woodpecker’s (Campephilus principalis; Figure 1) ecology, evolution, conservation, and probable extirpation is gripping. This is a story of habitat loss, overhunting, political missteps, greed, and missed opportunities to save this spectacular North American bird. Although it is most likely extinct, many recent books have been published on ivory-bills. These provide a wealth of information, drawings, and photos that can be used in lecture (Weidensaul, 2002; Hoose, 2004; Jackson, 2004; Gallagher, 2005; Hill, 2007; Steinberg, 2008; Snyder et al., 2009; Bales, 2010). The only existing study of this species (Tanner, 1942) provides a wealth of information as well. In addition, Hill et al. (2006) provide audio recordings of woodpecker species in the same genus as ivory-bills (Campephilus), and the Macaulay Library at the Cornell Laboratory of Ornithology has many audio recordings of the genus online, including ivory-bills from 1935. Short (1982) provides beautiful color plates representing most species of woodpeckers. An excellent documentary on ivory-bills is available on DVD (Crocker, 2010). If time permits, this 85-minute film is a great supplement for students to watch (although I have not used it in my class).

Figure 1.

Images of the ivory-billed woodpecker (Campephilus principalis), pileated woodpecker (Dryocopus pileatus), and imperial woodpecker (C. imperialis) from Short (1982). Courtesy of Delaware Museum of Natural History.

Figure 1.

Images of the ivory-billed woodpecker (Campephilus principalis), pileated woodpecker (Dryocopus pileatus), and imperial woodpecker (C. imperialis) from Short (1982). Courtesy of Delaware Museum of Natural History.

This woodpecker, with its ivory-white bill and red crest, captivated Native Americans and European settlers. Native Americans found the white bill magical, and they thought that possessing it would give them the bird’s powers (Hoose, 2004). Consequently, ivory-bills were killed for their bills and plumage as long as humans coexisted with them, probably for centuries (Jackson, 2004). This, coupled with habitat loss, led to the demise of a bird that required large expanses of bottomland forest with an abundance of large and recently dead trees. Table 1 provides a timeline of significant events associated with the ivory-billed woodpecker.

Table 1.

Timeline of the significant events associated with the ivory-billed woodpecker’s decline and efforts to find it. Much of the information is available in Hoose (2004) and Jackson (2004). Lack of citation in the timeline indicates material obtained from Hoose and Jackson. Other sources are cited.

DateEvent
1712–1725 Mark Catesby, the first European to discover ivory-bills, saw many white bills adorning the headdresses of Native American warriors. 
1820 John James Audubon heard the double-hammer of ivory-bills constantly while floating down the Mississippi River. He saw frontiersmen along the shore with the heads of ivory-bills for sale to steamboat passengers. He also saw the heads and bills of this woodpecker used as ornaments on the belts of Native American chiefs. Audubon killed the first of his many ivory-bills on 20 December 1820. 
1865 By the end of the Civil War, the logging boom began in the South, reducing the ivory-bill’s range through loss of bottomland forest habitat. 
1880–1915 Hunting of ivory-bills accelerated because the birds were coveted specimens for scientific and personal collections. Approximately 200 birds were killed during this time (see Jackson, 2004: fig. 3.4, p. 74). 
Early 1900s By the turn of the century, habitat loss continued while ivory-bills became increasingly rare. The species was considered extirpated in Louisiana by 1900. 
1924 Ivory-bills were considered extremely rare. Dr. Arthur Allen of Cornell observed a pair in Osceola County, Florida. This was the first confirmed sighting in years. Two taxidermists killed both birds the day Allen left them. 
Early 1930s Many considered ivory-bills extinct in the United States. 
1932 On 15 April, Mason Spencer shot a male ivory-bill in Madison Parish, Louisiana, near an area that was to become known as the Singer Tract. Spencer did so to confirm the existence of this species in the state. 
1935 Arthur Allen, J. J. Kuhn, Paul Kellogg, George Sutton, and James Tanner observed ivory-bills in the bottomland forest of the Singer Tract (Sutton, 1936). 
1937–1939 James Tanner returned to the Singer Tract to conduct the only study of ivory-bills (Tanner, 1942; Bales [2010] detailed Tanner’s experience). 
1939–1944 Chicago Mill and Lumber Company accelerated logging of Singer Tract. World War II and the availability of German prisoners as free labor further accelerated logging. Efforts by the Audubon Society to save the Singer Tract as a wildlife refuge failed. 
1944 Last ivory-bill observed in the Singer Tract. 
1948 Logging of Singer Tract completed. John Dennis observed a breeding pair of ivory-bills in Cuba (Snyder et al., 2009). 
1956 George and Nancy Lamb found evidence of ivory-bills in Cuba (Snyder et al., 2009). 
1958 Whitney Eastman provided credible evidence of ivory-bills along the Chipola River in Florida (Snyder et al., 2009). 
1967 Reports of ivory-bills in the Big Thicket region of east Texas. Solid confirmation never obtained (Snyder et al., 2009). 
1971 Ivory-bill photographed by Fielding Lewis near Franklin, Louisiana, in 1971 and given to George Lowery, who presented these photographs at the 1971 meeting of the American Ornithologists’ Union. Criticism and accusation of fraud followed and were a sore point for Lowery until his death in 1978 (photograph in Gallagher, 2005; Steinberg, 2008). 
1986–1987 Ivory-bills sighted in Cuba. No other confirmed sightings after 1987. 
1999 A seemingly credible sighting in the Pearl River Wildlife Refuge north of New Orleans. No confirmation came, despite a concerted search. 
2002 The 30-day Pearl River expedition was undertaken in search of ivory-bills. Double-hammer rapping recorded on 27 January made national news. This recording was later thought to be of gunshot echoes. 
2004–2005 Ornithologists observed what appeared to be an ivory-billed woodpecker in Arkansas (Fitzpatrick et al., 2005; Gallagher, 2005). David Luneau recorded a video clip of a large black-and-white woodpecker in flight at the same location. The evidence was debated by ornithologists (Fitzpatrick et al., 2006a, 2006b, 2006c, 2007; Jackson, 2006a, 2006b; Sibley et al., 2006, 2007; Collinson, 2007; Crocker et al., 2010). Additional confirmation in the form of photographs or recordings was never obtained. 
2005–2009 Cornell-organized search continued in Arkansas. No additional evidence gathered. 
2005–2006 Evidence of ivory-bills was reported from the Choctawhatchee River in the Florida panhandle (Hill et al., 2006; Hill, 2007). Conclusive evidence has yet to be obtained. 
2007–present The search for ivory-billed woodpeckers continues, with regular, unconfirmed sightings reported. 
DateEvent
1712–1725 Mark Catesby, the first European to discover ivory-bills, saw many white bills adorning the headdresses of Native American warriors. 
1820 John James Audubon heard the double-hammer of ivory-bills constantly while floating down the Mississippi River. He saw frontiersmen along the shore with the heads of ivory-bills for sale to steamboat passengers. He also saw the heads and bills of this woodpecker used as ornaments on the belts of Native American chiefs. Audubon killed the first of his many ivory-bills on 20 December 1820. 
1865 By the end of the Civil War, the logging boom began in the South, reducing the ivory-bill’s range through loss of bottomland forest habitat. 
1880–1915 Hunting of ivory-bills accelerated because the birds were coveted specimens for scientific and personal collections. Approximately 200 birds were killed during this time (see Jackson, 2004: fig. 3.4, p. 74). 
Early 1900s By the turn of the century, habitat loss continued while ivory-bills became increasingly rare. The species was considered extirpated in Louisiana by 1900. 
1924 Ivory-bills were considered extremely rare. Dr. Arthur Allen of Cornell observed a pair in Osceola County, Florida. This was the first confirmed sighting in years. Two taxidermists killed both birds the day Allen left them. 
Early 1930s Many considered ivory-bills extinct in the United States. 
1932 On 15 April, Mason Spencer shot a male ivory-bill in Madison Parish, Louisiana, near an area that was to become known as the Singer Tract. Spencer did so to confirm the existence of this species in the state. 
1935 Arthur Allen, J. J. Kuhn, Paul Kellogg, George Sutton, and James Tanner observed ivory-bills in the bottomland forest of the Singer Tract (Sutton, 1936). 
1937–1939 James Tanner returned to the Singer Tract to conduct the only study of ivory-bills (Tanner, 1942; Bales [2010] detailed Tanner’s experience). 
1939–1944 Chicago Mill and Lumber Company accelerated logging of Singer Tract. World War II and the availability of German prisoners as free labor further accelerated logging. Efforts by the Audubon Society to save the Singer Tract as a wildlife refuge failed. 
1944 Last ivory-bill observed in the Singer Tract. 
1948 Logging of Singer Tract completed. John Dennis observed a breeding pair of ivory-bills in Cuba (Snyder et al., 2009). 
1956 George and Nancy Lamb found evidence of ivory-bills in Cuba (Snyder et al., 2009). 
1958 Whitney Eastman provided credible evidence of ivory-bills along the Chipola River in Florida (Snyder et al., 2009). 
1967 Reports of ivory-bills in the Big Thicket region of east Texas. Solid confirmation never obtained (Snyder et al., 2009). 
1971 Ivory-bill photographed by Fielding Lewis near Franklin, Louisiana, in 1971 and given to George Lowery, who presented these photographs at the 1971 meeting of the American Ornithologists’ Union. Criticism and accusation of fraud followed and were a sore point for Lowery until his death in 1978 (photograph in Gallagher, 2005; Steinberg, 2008). 
1986–1987 Ivory-bills sighted in Cuba. No other confirmed sightings after 1987. 
1999 A seemingly credible sighting in the Pearl River Wildlife Refuge north of New Orleans. No confirmation came, despite a concerted search. 
2002 The 30-day Pearl River expedition was undertaken in search of ivory-bills. Double-hammer rapping recorded on 27 January made national news. This recording was later thought to be of gunshot echoes. 
2004–2005 Ornithologists observed what appeared to be an ivory-billed woodpecker in Arkansas (Fitzpatrick et al., 2005; Gallagher, 2005). David Luneau recorded a video clip of a large black-and-white woodpecker in flight at the same location. The evidence was debated by ornithologists (Fitzpatrick et al., 2006a, 2006b, 2006c, 2007; Jackson, 2006a, 2006b; Sibley et al., 2006, 2007; Collinson, 2007; Crocker et al., 2010). Additional confirmation in the form of photographs or recordings was never obtained. 
2005–2009 Cornell-organized search continued in Arkansas. No additional evidence gathered. 
2005–2006 Evidence of ivory-bills was reported from the Choctawhatchee River in the Florida panhandle (Hill et al., 2006; Hill, 2007). Conclusive evidence has yet to be obtained. 
2007–present The search for ivory-billed woodpeckers continues, with regular, unconfirmed sightings reported. 

Teaching with the Ivory-bill Story

The ivory-bill activity is typical of my approach to teaching: leading with a story that captures my students’ attention before shifting into concepts. There are few topics that I am more passionate about than that of the ivory-billed woodpecker. As a child, I was fixated by the image of the ivory-bill in my Golden Guide to Birds. As an undergraduate, I was mesmerized by George Sutton’s story of being on the Louisiana expedition that rediscovered ivory- bills in 1935 (Sutton, 1936). As a graduate student at the University of Oklahoma, I met Sutton (at the time a retired professor), knowing that he was one of the last people to see living ivory-bills and one of only a few artists to draw the species from living, wild birds. As a biologist, I have roamed the swamps of Arkansas, Florida, and Oklahoma, always listening and looking for this bird. Providing students with my personal connection to the bird conveys the passion I have for this topic. This lecture is extremely colorful and visual, with PowerPoint images from the recent books cited above, and covers the ivory-billed woodpecker’s demise, missed opportunities to save it, its rediscoveries followed by additional disappearances, and the continued, obsessive search to find it. After leading with this story, I introduce the biogeography, morphology, calls and communication, and taxonomy of the woodpecker genus Campephilus. Eight species are in South America, two in Central America, and two in North America (including the imperial, and ignoring disagreement on the taxonomy of Cuban birds). They all have chisel-shaped bills, and they all communicate using the double-hammer rapping sound made by pounding the bill quickly against a tree twice.

Discussion-based Activity

Once the background is laid out and the story told, the Socratic Method comes into play as I provoke class discussion by presenting the following questions:

  1. Why do so many species of crested woodpeckers exist in the Western Hemisphere?

  2. Why are all known species that characteristically signal with the double-hammer also crested?

  3. Why are New World woodpeckers that characteristically produce the double-hammer considered members of the same genus (Campephilus)?

  4. Why do all Campephilus species live in the Western Hemisphere, most in South America (Figure 2)?

  5. Why do the two largest species (ivory-bill and imperial; Figure 1) have the most northern distributions (Figures 2)?

  6. Why do ivory-billed woodpeckers and pileated woodpeckers (Dryocopus pileatus) look so similar (Figure 1)?

  7. Why do other species of Dryocopus look similar to other species of Campephilus (Figures 2, 3, and 8)?

  8. What explanations and hypotheses can be generated to address these questions?

  9. What evidence is needed to support or refute these hypotheses?

Figure 2.

Distribution of the 11 species of Campephilus, based on BirdLife International (http://www.birdlife.org). Courtesy of Delaware Museum of Natural History and National Geographic Society.

Figure 2.

Distribution of the 11 species of Campephilus, based on BirdLife International (http://www.birdlife.org). Courtesy of Delaware Museum of Natural History and National Geographic Society.

Some of these questions remain to be answered by woodpecker biologists and are wonderful examples of open-ended questions. Pigliucci (2002) stressed the importance of avoiding canned class activities that lead to preordained results, which mislead students into thinking that science has most of the answers. Pigliucci also stressed that science is an activity of open-ended inquiry; thus, class activities should be oriented toward open-ended inquiry as well. Generating and discussing unanswered questions about the evolution of these woodpeckers fits with this approach. Students generate hypotheses yet to be tested by woodpecker biologists, so most of their hypotheses remain viable. My students are thrilled to be dealing with current scientific issues.

I have been using this ivory-bill activity for 10 years. Students are moved by this story, so their enthusiasm for generating hypotheses is always high. Discussion in my large classes is tremendous. Students generate many of the same hypotheses each semester, including (1) that crested species evolved from a common ancestor in South America early in the history of woodpeckers, (2) that the double-hammer species of Campephilus evolved from a crested-common ancestor, (3) that imperial and ivory-billed woodpeckers evolved from a recent common ancestor, and (4) that ivory-bills and pileated woodpeckers look similar because they are closely related.

The resulting class discussion can easily last 30 minutes. I let it continue as long as students are interactive and enthusiastic. Once a sufficient number of hypotheses has been generated, I ask what evidence is needed to support or refute each. Discussion continues before I introduce the concept of the phylogenetic tree (diagram showing descent and relatedness based on ancestry) using an example based on woodpecker morphology that I developed from Short (1982; Figure 3). Students are led through the tree, indicating the key points: (1) Crested woodpeckers probably evolved from round-headed ancestors; (2) Woodpeckers that produce the double-hammer probably evolved from a crested ancestor; and (3) Larger, black-bodied species probably evolved from smaller, light-bodied ancestors that produced the double-hammer. I ask students to indicate which Darwinian theories of evolution are clearly exemplified by the phylogenetic tree and to provide evidence to support these claims. Students readily recognize evolution as such, descent with modification, descent from a common ancestor, and multiplication of species. They recognize that sexual selection is an evolutionary mechanism involved in this case, given the sexual dimorphism of Campephilus species as seen in images of male and female ivory-billed, imperial, and magellanic woodpeckers. In every class, students suggest that natural selection is a relevant mechanism as well. When I ask them where on the phylogenetic tree natural selection is most clearly indicated, they have difficulties. I point out that it would be difficult to imagine natural selection not being a component of woodpecker evolution, but evidence for this theory is least obvious on the phylogenetic tree. This provokes extensive discussion on what constitutes evidence, speculation, and assumption. As the discussion develops, it becomes clear that with the evidence available on the phylogenetic tree, sexual selection is more obvious than natural selection. I reemphasize that we are not dismissing natural selection as a driving evolutionary force, but that the evidence for sexual selection is more obvious from the images of Campephilus. In some semesters, students counter-argue that the chisel-shaped bill is an obvious example of natural selection. This is an excellent counterpoint that I do not get every semester.

Figure 3.

Simple woodpecker phylogenetic tree based roughly on Short (1982). Courtesy of Delaware Museum of Natural History.

Figure 3.

Simple woodpecker phylogenetic tree based roughly on Short (1982). Courtesy of Delaware Museum of Natural History.

The discussion shifts to the importance of corroborating evidence, and I ask whether this morphologically based phylogenetic tree is an accurate representation of woodpecker evolution. If not, what additional evidence is needed? Students typically suggest the need for genetic evidence. With this, I introduce the concepts of (1) cladistics (a classification scheme based on the historical sequence of divergent events as revealed by the presence of shared derived characteristics) and (2) cladograms (an evolutionary tree reflecting the results of cladistic analysis, often using molecular evidence) (Freeman & Herron, 2007). I briefly show them a recently published cladogram for Campephilus (Fleischer et al., 2006; Figure 4). We do not dwell on this figure, other than to explain the concept of primary literature and the importance of molecular evidence. I then show a simplified and modified version of the cladogram in Fleischer et al. (2006; Figure 5) and ask whether the cladogram and previous phylogenetic tree corroborate each other. Students agree that they do.

Figure 4.

Phylogenetic tree for Campephilus from Fleischer et al. (2006). Courtesy of HighWire Press.

Figure 4.

Phylogenetic tree for Campephilus from Fleischer et al. (2006). Courtesy of HighWire Press.

Figure 5.

Redrawing and simplification of Fleischer et al.’s (2006) phylogenetic tree, using images from Short (1982). Courtesy of Delaware Museum of Natural History.

Figure 5.

Redrawing and simplification of Fleischer et al.’s (2006) phylogenetic tree, using images from Short (1982). Courtesy of Delaware Museum of Natural History.

Discussion shifts back to the two largest members of the species, the imperial and ivory-billed woodpeckers. The cladogram suggests that they descended from a common ancestor 2 million years ago, yet these two forest dwellers’ ranges are separated by an arid, unforested region of Mexico and Texas where these birds cannot live. Given this, I ask students to suggest what other corroborating evidence is needed to confirm that these two woodpeckers evolved from a recent common ancestor. Students respond that fossil evidence is important. With this, I show (Figure 6) that fossil evidence suggests that a continuous forest existed from western Mexico to the southeastern United States 2 million year ago and that a 2-million-year-old fossil (Campephilus dalquesti; see Jackson 2004), apparently a common ancestor, was discovered in central Texas.

Figure 6.

Distributions of the ivory-billed woodpecker (Campephilus principalis) and imperial woodpecker (C. imperialis), based on BirdLife International (http://www.birdlife.org) and Tanner (1942). Star represents location where fossils of the extinct C. dalquesti were found in Scurry County, Texas (Jackson, 2004). Solid green lines indicate a rough estimate of forested area, and dashed green lines a rough estimate of the range of ancient forests. Courtesy of Delaware Museum of Natural History and National Geographic Society.

Figure 6.

Distributions of the ivory-billed woodpecker (Campephilus principalis) and imperial woodpecker (C. imperialis), based on BirdLife International (http://www.birdlife.org) and Tanner (1942). Star represents location where fossils of the extinct C. dalquesti were found in Scurry County, Texas (Jackson, 2004). Solid green lines indicate a rough estimate of forested area, and dashed green lines a rough estimate of the range of ancient forests. Courtesy of Delaware Museum of Natural History and National Geographic Society.

The next phase of class discussion is to ask whether the major questions of Campephilus evolution have been answered. Students feel that they have. I tell them that two more detailed phylogenetic trees have been published (Webb & Moore, 2005; Benz et al., 2006) and show them Benz et al.’s (2006) cladogram (Figure 7), which provides more information on woodpecker evolution, including many more genera than are presented by Fleischer et al. (2006). From this cladogram, we see that crested woodpeckers are found in both the New World and the Old World and that crests may have evolved independently multiple times (or that crests were lost multiple times). Surprisingly, ivory-billed woodpeckers are not closely related to pileated woodpeckers as suggested by Short (1982), who placed both genera in the tribe Campephilini, but are more closely related to orange-backed and greater flameback woodpeckers, both considered Asian “ivory-bill” species. I ask for hypotheses explaining how a group that diversified in South America 5 million years ago could be most closely related to Asian species. These questions prompt lively hypothesizing by students. Some of their hypotheses include the following:

Figure 7.

Woodpecker phylogenetic tree from Benz et al. (2006), including more species of woodpeckers than in Fleischer et al. (2006). Red boxes indicate species with crests. Courtesy of Delaware Museum of Natural History and Elsevier B.V.

Figure 7.

Woodpecker phylogenetic tree from Benz et al. (2006), including more species of woodpeckers than in Fleischer et al. (2006). Red boxes indicate species with crests. Courtesy of Delaware Museum of Natural History and Elsevier B.V.

  • An ancestral form flew across the Pacific Ocean.

  • The common ancestor existed when the continents were connected, then the two groups diverged when the continents separated.

  • A South American ancestor dispersed up through North America, across the Bering Strait, down through Siberia, to the current Asian distribution, where speciation then occurred.

  • The reverse of hypothesis 3: The group evolved in Asia, and species dispersed to South America.

  • Ancestors lived in northern Eurasia and northern North America during a warm period. Global cooling and an advancing ice age forced woodpeckers south into Asia and South and Central America, where speciation occurred.

After sufficient discussion and hypothesizing, I explain that hypotheses 1 and 2 are unlikely. Most species of woodpeckers are not strong fliers capable of traveling the long distances required to cross the Pacific Ocean. Even though ivory-bills were odd among woodpeckers in being strong fliers (often compared to pintail ducks in this regard), we have no evidence that they were long-distance fliers. With respect to the second hypothesis, woodpeckers evolved 15 million years ago, long after the continents separated during the Jurassic more than 140 million years ago.

I then explain that hypotheses 3, 4, and 5 are still debated by researchers (and thus are examples of open inquiry) and that more evidence, especially fossil evidence, will be needed to resolve the debate. This is an excellent example for students to see that science is an ongoing process. As more evidence is gathered to answer existing questions, more questions are generated.

I ask the class to hypothesize why pileated woodpeckers look so similar to ivory-bills despite not being closely related. I further ask whether this has anything to do with the two species coexisting. Finally, I ask why (1) throughout North, Central, and South America, most species of Campephilus coexist with a member of the pileated genus Dryocopus; and (2) one species of the genus Dryocopus also coexists with the Old World ivory-bills in Southeast Asia and India (Figure 8). Students are asked to generate hypotheses, which typically include these:

Figure 8.

Distribution of New World and Old World ivory-bills, as well as species of the genus Dryocopus. Courtesy of Delaware Museum of Natural History and National Geographic Society.

Figure 8.

Distribution of New World and Old World ivory-bills, as well as species of the genus Dryocopus. Courtesy of Delaware Museum of Natural History and National Geographic Society.

  • Convergent evolution has occurred, indicating that some adaptation exists for shape and coloration in forest habitat where these two genera reside.

  • One species may be mimicking the other.

  • Some cooperative association between these species exists that favors similar morphology.

I give the class sufficient time to generate hypotheses before asking them if they are ready to hear the correct explanation. Students are surprised and pleased that woodpecker biologists have generated similar hypotheses, yet these currently lack sufficient evidence to be supported or refuted. This is an extraordinarily powerful example, demonstrating that science is a never-ending, ongoing process of open inquiry.

Conclusion

I have found that for my large courses to succeed, the discussion-based approach must be established early in the semester. Furthermore, provoking lively discussion of a topic requires leading with the best, relevant story I have, told with as much passion as I possess. If I can capture my students’ interest with this story, tremendous discussion usually follows. The ivory-billed woodpecker activity accomplishes these two goals and sets the tone early. This technique has been very successful. The activity provides both a review and application of the scientific method and evolutionary theory covered at the beginning of the semester. Long-term retention and self-motivation are likely to correlate best with excitement and involvement during class. A successful class is one in which many students join the discussion, contribute ideas, and collaborate in moving the topic forward. This is an exciting approach that helps build an ongoing relationship by drawing students into the subject matter. I firmly believe that this kind of experience helps stimulate intellectual engagement and interest in a topic that persists long after the course has ended.

Acknowledgments

I thank Jerome Jackson for his thoughts on storytelling, teaching, and George Sutton, and especially for sharing his knowledge of woodpeckers in general and ivory-billed woodpeckers in particular. I also thank Brett Benz, Mark Robbins, and David Webb for sharing their knowledge of woodpeckers with me. Phil Crowley, Jerome Jackson, Doug Mock, Rees Storm, Randal Voss, and three anonymous reviewers provided helpful comments on the manuscript. My thanks to John Fitzpatrick and Tammy Bishop of the Cornell Laboratory of Ornithology for permission to use George Sutton’s watercolor of an ivory-billed woodpecker for the cover of ABT. I thank the Delaware Museum of Natural History for permission to use the beautiful images of woodpeckers painted by George Sandström for Lester Short’s Woodpeckers of the World; Elsevier B.V. for permission to use the figure from Benz et al. (2006); HighWire Press for permission to use the figure from Fleischer et al. (2006); and the National Geographic Society for permission to use images of the Eastern and Western Hemispheres. My sincere thanks to Bill Kroen and the NABT Four-year College and University Section Biology Teaching Award Committee, as well as Betsy Ott and the NABT Evolution Education Award Committee, for giving me these two awards. Dossiers for both award competitions included this activity on storytelling and the ivory-billed woodpecker.

References

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