Hands-on research experiences are crucial opportunities for students to learn about the nature of inquiry, gain confidence in solving problems, and gain self-identify as scientists (1-4). However, most traditional undergraduate research opportunities only benefit a small number of well-prepared students. In contrast, course-based undergraduate research experiences (CUREs) introduce many more students to authentic research experiences. They can therefore increase inclusivity for students who are financially or time-limited (5) and provide equitable access to research experiences early in a college career (6).
Although many excellent CUREs have been developed for laboratory courses in cellular and molecular biology (see CUREnet for examples; 7), CUREs that engage students in field sciences such as ecology are rare (8-10). Nevertheless, they are critically important for several reasons. First, they help prepare students for the workforce by teaching them hard skills used in wildlife and conservation fields. Secondly, they train students in soft skills that employers highly value, such as problem-solving, teamwork, and written communication (11). Third, they allow students to work on authentic data with unknown results, which improves data literacy (12,13). Lastly, they expose students to ecological and environmental threats, as well as how scientists approach investigating and managing these issues.
In spite of these many benefits of field-based CUREs, instructors can be reluctant to develop them. They can be time consuming to establish and maintain, and do not always fit within the time available for a lab section. Working with vertebrates poses additional challenges because of difficulty obtaining Institutional Animal Care and Use Committee (IACUC) approvals and/or institutional support for liability issues (14). Furthermore, adequate amounts of ecological data can be time-consuming to collect, resulting in insufficient data to analyze for many classes that attempt to incorporate field studies (15).
Squirrel-Net (http://squirrel-net.org), is a group of mammalogists from eight institutions across the U.S. who wanted to integrate meaningful, field-based CUREs into undergraduate biology education. We have designed a series of inquiry-based lessons that engage students in authentic research by examining the ecology of squirrels, a widely distributed, highly visible, and charismatic group of mammals (16,17; Figure 1). These modules are designed to broaden the availability of field-based CUREs and minimize challenges that often hamper their implementation. First, participating students use the same protocols to collect data, which they submit to a multi-institutional database, alleviating the pressure to collect sufficient data in a single course or at a single institution. By combining data across geographic regions, students can evaluate more variables and therefore test a wider range of hypotheses than would be possible in a single class period. This in turn leads to more creativity and control over a project, with the potential to increase student learning gains in scientific communication, persistence in science, self-confidence and self-efficacy (4). The combined datasets also provide ready-to-analyze data for times when individual classes are unable to collect their own data (e.g., due to inclement weather or lack of animal activity), permit inclusion for students with physical disabilities, and can form the basis for activities that focus on data analysis and management. In addition, Squirrel-Net provides templates for institutional approvals (e.g., IACUC, Animal Use Protocols). Furthermore, we have tested each module at different institutions in different semesters and have found they are easily integrated into a wide range of undergraduate courses and can be combined with other Squirrel-Net modules across a curriculum to provide an integrated set of research activities. We offer suggestions on how each module can be used independently or networked with other modules throughout an entire curriculum.
Not only do our modules lower barriers for using field-based CUREs, they also encourage student engagement. Studying animals is intrinsically interesting and compelling for many students. Specifically, observing live animals can foster strong personal connections with science and nature in students from urban settings, who may be less familiar with wildlife (21). Behavioral ecology studies therefore provide unique opportunities to engage students in the scientific process, from generating and testing hypotheses to strengthening quantitative skills and drawing conclusions from data (22). Furthermore, a sense of belonging to a community is a strong predictor of persistence in science, and this may be particularly important for underrepresented groups (23). Our modules provide this sense of community through increasing collaboration with peers, working more closely with teaching assistants and professors, and providing opportunities to be part of a larger scientific network (24).
Below, we briefly summarize each of the four CURE modules and suggest ways that they can be adapted to different levels of inquiry to be used singly or together in a curriculum.
Squirreling Around for Science: Observing Sciurid Rodents to Investigate Animal Behavior
The first module in our series engages students in behavioral observations (Figure 2A) to examine how trade-offs influence the time spent in different behaviors (25). In this CURE, students work in pairs to observe a focal squirrel for 5 minutes each, recording its behavior at 20 second intervals. These data are then tallied to determine what proportion of time squirrels spend in various behavior states (e.g., vigilance or foraging). Additional data such as habitat type, weather, and proximity to humans are also collected, allowing students to test hypotheses about how extrinsic factors influence behavior or questions such as how sociality or urbanization affect squirrel foraging decisions. One advantage of this module is that it requires no specialized equipment (although binoculars or video-recording mobile devices may be helpful). Finally, as student observers are not influencing squirrel behavior, most institutional IACUCs do not consider the module as requiring any assurance or approval.
Sorry to Eat and Run: A Lesson Plan for Testing Trade-offs in Squirrel Behavior Using Giving Up Densities (GUDs)
This lesson plan assesses squirrel foraging trade-offs by measuring giving up density (GUD), or the amount of food left when an animal abandons a patch (26). The concept of GUD is based on optimal foraging theory and represents the point at which foraging benefits no longer outweigh foraging costs (27). Therefore, a lower GUD indicates either a lower cost of foraging (e.g., a safer patch or food that is easier to handle or digest), a higher benefit (e.g., nutrient-rich food), or both. In this module, students place trays filled with a known quantity of seeds and sand at varying distances from safety (Figure 2B), collect them at the end of the day or night, and then reweigh seeds to determine GUD. Students record data on habitat type, proximity to human structures, seed type, and hours the tray was available to animals (diurnal vs. nocturnal). Results can then be interpreted in simple terms of foraging vs. vigilance or in the context of more complex interpretations (e.g., optimal foraging theory or the “landscape of fear” [28,29]). The equipment needed is inexpensive and readily available (trays, play sand, and a food source), and while the module may require IACUC approval, it requires little specialized instructor expertise to facilitate.
How Many Squirrels Are in the Shrubs: A Lesson for Comparing Methods for Population Estimation
In this more-advanced module students compare the results of three population estimation techniques and evaluate the underlying assumptions of each (30). Population estimates are essential for many conservation and management techniques, and this module reveals to students that these estimates can differ widely based on assumptions and approach. In this module, students estimate the size of a single squirrel population using strip censuses, scat counts (Figure 2C), and camera traps. In strip censuses, students walk transects and record the distance to any detected squirrel. For scat counts, a number of plots within the area are cleared of scat, then new scat is counted on a return visit. Finally, camera traps are used to capture images of the focal species, and students estimate population size from the number of images. A standardized data sheet walks students through the calculations to estimate population size for each technique. Finally, as in the other modules, students also collect additional meta-data including habitat type, proximity to human structures, weather conditions, and other species observed during the surveys. Students can then compare population size estimates from each technique and consider how the assumptions underlying each technique might bias the outcomes. With the accompanying national database, this lab can also be extended to examine how each technique performs under varying environmental conditions (e.g., habitat type), with different species, or under differing community structures (types and numbers of other species). The only specialized equipment needed for this module are camera traps, although laser range finders can also be useful to measure distances.
Squirrels in Space: Using Radio Telemetry to Explore the Space Use and Movement of Sciurid Rodents
This advanced lesson plan using radio telemetry is aimed at upper division students in wildlife and ecology courses. In this module, students use antennae and receivers (Figure 2D) to locate and track radio-collared squirrels in order to better understand how they move in the landscape (31). They also collect data including habitat, proximity of the squirrel to human structures, and weather conditions. These data can be analyzed to answer questions about home range size, avoidance of roads, and interactions with other squirrels or other wildlife. Students can then interpret their findings through the lens of wildlife management and conservation. The lab requires radio telemetry equipment, which Squirrel-Net hopes to have for loan in the near future (for updates, see http://squirrel-net.org). Instructors must also obtain necessary permits and institutional IACUC approvals to trap, handle, and collar squirrels, making this module the most advanced in terms of both instructor facilitation and student skill development.
Levels of Inquiry
Although there is some discussion as to what constitutes a CURE (24, 32), at their core, they are inquiry-based activities where students "do" science within a course framework (24). Through the use of authentic research experiences, they provide undergraduate students with the structured guidance and practice to develop the scientific maturity and skills they will need for a successful career in science. Several authors have articulated the concept of levels of inquiry, where inquiry-based activities can be seen as a continuum moving from highly instructor-led to increasingly more student-led (e.g., 33-35). Our lesson plans are presented at levels of inquiry that are on the instructor-led end of the continuum (Table 1). However, the standardized collection of data and the use of national databases allow considerable flexibility for each deeper level of inquiry, and suggestions for added complexity are given within each module (25, 26, 30, 31) and Table 1.
The simplest form of each module (i.e., a single, 2-hour lab activity) is presented in each lesson plan (25, 26, 30, 31). However, one of the strengths of our modules is their adaptability; there are multiple ways to scaffold one or multiple modules into a single course or across the curriculum (Figure 3). Alternatively, a single module could be implemented at multiple levels within a single course or across several courses. For example, the Squirreling Around for Science module (25) could be used several times in an introductory ecology course, building complexity by sequentially considering more explanatory variables, exploring the literature to develop hypotheses, and using the national database to augment data and/or practice data "cleaning". Similarly, a single module could also be used at various levels of inquiry across several courses, allowing students to revisit the same research project several times throughout their coursework at increasing levels of complexity (Figure 3). Whether scaffolding within or across courses, focusing on one module or one taxonomic group (i.e., squirrels) can provide cohesion by reexamining a common theme while moving toward more independent thinking.
Through these innovative modules, Squirrel-Net seeks to lower barriers and increase accessibility to authentic field-based research. The modules are well-suited to this goal because they are easy to implement, often require minimal equipment investment, and have been field-tested with positive outcomes for students and instructors at multiple institutions. Additionally, we provide materials for instructors to work with local, charismatic mammals that are ubiquitous in the United States, including urban areas. Using squirrels as a model system, students can collect data either directly on or near most campuses, reducing barriers for students to access focal species. Finally, our approach is unique because each module connects to a national database, allowing for broader and more complex hypotheses and analyses than data collected from a single institution. The interactions among classes running the same module form the basis for a research network, which helps students develop a sense of belonging to a scientific community and accountability to peers to collect quality data. Each module is highly flexible and can be used at any level of inquiry or adapted to organisms other than squirrels. Lastly, a single module or multiple modules can be scaffolded within a course or more extensively throughout a curriculum, facilitating the intellectual growth of students to become independent and critical thinkers. We believe that this innovative approach to networked, field-ecology focused CUREs permits broad instructor adoption (37) across a wide variety of course levels and institutional types, providing positive student outcomes similar to traditional undergraduate research.
This material is based upon work supported by the National Science Foundation under a collaborative grant (Nos. 2013483, 2013281, 2013308, and 2013320). We would also like to acknowledge all of the students who provided helpful feedback on these modules as we developed and piloted them in our courses.
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