The inclusion of nonscientists in biological research projects has become a useful mechanism for capturing long-term ecological data while exposing students firsthand to science and the scientific method. I have combined several existing citizen-science-based research efforts focused on Danaus plexippus, the monarch butterfly, into a comprehensive yet simple ecological lab activity that is appropriate for all ages and biological backgrounds.

Background

““Citizen science”” is broadly defined as the involvement of nonprofessional scientists in a scientific research project. The inclusion of ““citizen scientists”” in ecological work has afforded researchers the benefit of large, diverse data sets collected by participants, often from their own yards or towns. Ecological research projects that involve the participation of local citizens provide a unique opportunity for community members of all ages to improve their scientific and ecological knowledge (Trumbull et al., 2000; Brewer, 2002). Butterflies have been an effective study organism for citizen-science projects and are known to be effective in promoting science learning in school-age children (Culin, 2002; Storm, 2007).

Citizen-science methods have been used with much success to study the migration and biology of the monarch butterfly, Danaus plexippus (Linnaeus, 1758), since the tagging project initiated by Fred and Norah Urquhart in 1938. Today, programs that incorporate citizen participation, such as Monarch Watch, Journey North, and the Monarch Larva Monitoring Project (MLMP), are more popular than ever. Monarch Watch was initiated by the University of Kansas in 1992. Participants in the program tag hundreds of thousands of monarchs each year, which has helped establish a long-term record of their migration routes (McCord, 1997). Journey North is an interactive, web-based reporting system that allows participants to report monarch sightings and share information about monarch migration routes through their towns (Howard & Davis, 2004, 2009). Researchers at the University of Minnesota developed MLMP to collect data on larval monarch populations as well as milkweed habitat. Volunteers across the United States and Canada monitor monarchs and milkweed in their areas, and their data are used to answer questions about monarch ecology during the breeding season (Prysby & Oberhauser, 1999).

Biology teachers perpetually face the challenge of engaging students of all ages in the process of science and are often seeking hands-on activities to help teach and enrich the standards and objectives for biology curricula. Here, I describe a field-based lab exercise for groups of any size that can be conducted in any North American location along the monarch migration route. This lab is intended for use by citizens and students of all ages and is designed to help teachers meet the objectives and standards of most states for middle school, high school, and college biology curricula. The main goals of the activity are to (1) increase participants' understanding of monarch biology, (2) inform them about the long-distance migration routes and timing of monarch migration, (3) introduce them to the biogeography of disease transmission of common external parasites of monarchs, and (4) provide an overview of monarch conservation measures that participants can take in their own communities. The activity is intended to enhance and develop factual, conceptual, procedural, and metacognitive knowledge in students at all grade levels and provides instructors with guidance on how to help students make connections to the larger conservation issues associated with this species' migration.

Study Species

The monarch butterfly occurs in two separate and distinct populations in North America. One group breeds east of the Rocky Mountains and overwinters in central Mexico, and the other breeds west of the Rockies and overwinters in southern California. Nectar resources across the species' distribution are strongly threatened by agriculture, herbicide use, and increases in human development.

Monarchs are large butterflies with a large wingspan (8.2––10.5 cm). Males can be differentiated by the presence of a black scent patch located on the hind wing (Figure 1). Females lay 500––700 eggs on the underside of leaves of milkweeds (family Asclepidaceae: Asclepias spp.). Feeding larvae sequester cardenolides (also called ““cardiac glycosides””) from the milkweed plants, which are poisonous to most vertebrates (Brower & Moffit, 1974).

Figure 1.

Monarch butterflies advertise their toxicity with a bright orange, black, and white color pattern. (A) The male carries a black scent patch on the lower hind-wing vein below. (B) The female lacks this structure and has thicker vein pigmentation than the male.

Figure 1.

Monarch butterflies advertise their toxicity with a bright orange, black, and white color pattern. (A) The male carries a black scent patch on the lower hind-wing vein below. (B) The female lacks this structure and has thicker vein pigmentation than the male.

Pupation to the adult stage typically takes 9 to 15 days under normal temperatures. Monarch eggs and larvae are vulnerable to desiccation and elevated temperatures. Several studies have shown that temperatures above 35°°C are lethal to all stages of monarch development (Zalucki, 1982; Malcolm et al., 1987). The migratory nature of monarchs has been linked to the widespread transmission of different types of parasites, including the tachinid fly Lespesia archippivora, the bacterium Micrococcus flacidifex danai, and the protozoan Ophryocystis elektroscirrha (Altizer, 2001; Altizer et al., 2001). The latter, an obligate ectoparasite believed to have coevolved with monarch and queen butterflies, may be negatively affecting monarch populations in the United States.

Monarch Migration Patterns

Monarch butterflies in eastern North America undergo the longest insect migration in the world, traveling as far as 3000 km from Canadian breeding sites to overwintering sites in the mountains around Mexico City (Brower, 1995). Adult butterflies that emerge during August to October are long-lived and nonreproductive. They spend 6 to 8 months migrating either to southern California (the western population) or to Mexico (the eastern) (Figure 2). This long journey south depends on the ability of monarchs to find nectar and safe resting spots along the way (Brower et al., 2006). Unfortunately, agriculture and other human development have diminished the wildlife corridors used by migrating monarchs and decreased the availability of milkweed.

Overwintering sites in Mexico occur west of Mexico City at mountain elevations of 3000 m above sea level. The monarchs gather there in dense, overlapping aggregations, covering Oyamel fir trees and vegetation throughout the winter and into the spring. The following May, the adults become reproductive and head toward the northern breeding grounds, reproducing and dying along the way. Their offspring migrate north in successive generations, reproducing every 2 to 5 weeks.

Figure 2.

(A) Every fall, monarch butterflies begin their journey south, which takes them as far as 3000 km and lasts up to 8 months. Monarch populations on the West Coast overwinter in southern California, while those in Eastern North America travel all the way to the mountains of southern Mexico. (B) The following spring, the offspring of the original migrants head north, and successive generations continue toward their ancestors' places of origin, reproducing every 2––5 weeks along the way. Question marks indicate the locations of several southern populations that may not be migratory at all, perhaps staying in the same temperate location year-round.

Figure 2.

(A) Every fall, monarch butterflies begin their journey south, which takes them as far as 3000 km and lasts up to 8 months. Monarch populations on the West Coast overwinter in southern California, while those in Eastern North America travel all the way to the mountains of southern Mexico. (B) The following spring, the offspring of the original migrants head north, and successive generations continue toward their ancestors' places of origin, reproducing every 2––5 weeks along the way. Question marks indicate the locations of several southern populations that may not be migratory at all, perhaps staying in the same temperate location year-round.

Teacher Notes for Preparation

This lab exercise takes students outside the classroom and into the natural world to practice applying scientific method and data collection in an ecological context. Before they go into the field, the students should be instructed on the biology of the monarch butterfly and the process of long-distance animal migration. The instructor should clearly explain that monarchs migrate every winter to track their host plant, milkweed, to warmer temperatures. The fact that monarchs are intimately tied with milkweed is a critical concept that should be emphasized early on.

Rearing monarch butterflies in the classroom before conducting this lab activity is an effective way to engage students in the tagging activity. Monarch rearing kits are inexpensive and are available through the Monarch Watch Shop (http://shop.monarchwatch.org, item 113232). Exposing students to the development of individual butterflies in the classroom may serve to increase their interest in the species as a whole, making the lab activity more effective. Rearing butterflies allows students to observe the metamorphosis of caterpillars to adult butterflies, learning about the different ecological requirements a butterfly has during the different stages of its life. Before adult butterflies emerge, students can learn about the risks that parasites pose to butterflies during their development, including infestation with O. elektroscirrha. Introducing these topics while students are rearing their own butterflies is one way to strengthen the connections between monarch health, migration, and conservation.

Methods

The methods conducted during this lab exercise can be adjusted depending on the grade level involved and the specific focus that the instructor chooses to emphasize. The following materials are required:

  • A hand-held butterfly net for each participant (nets are available from the Monarch Watch Shop: http://shop.monarchwatch.org, item 120003)

  • Data sheet and tags downloaded from http://shop.monarchwatch.org

  • Data sheets for reporting monarch migration rate and habitat data (available from http://www.learner.org/jnorth/tm/monarch/FallDataSummary.html)

  • A parasite test kit from Monarch Health (available free of charge from http://www.monarchparasites.org; alternatively, you can acquire your own disposable latex gloves, clear tape stickers, and blank index cards)

  • (Optional) gardening materials and Asclepias seeds or seedlings for establishing a certified ““monarch waystation”” as a follow-up exercise

Data Collection

To find a suitable sampling location for catching and tagging monarchs, I suggest locating areas with ample nectar flowers that will be in bloom during the peak monarch migration through your area. These include, but are not limited to, milkweed, joe-pye weed (Eupatorium purpureum), thistle (family Asteraceae), ironweed (Vernonia altissima), and butterfly bush (Buddleia spp.). You will first need to determine the latitude of your sampling location to determine the time frame of peak monarch migration through your area (see Table 1). Sunny days should be chosen, preferably between 1100 and 1600 hours, to survey monarchs feeding quietly on patches of nectar plants.

Table 1.

Latitude and peak abundance dates of monarch migration through North America in 2009 as reported by Monarch Watch (http://www.monarchwatch.org).

LatitudePeak in Monarch AbundanceMidpoint
49 18––30 August 26 August 
47 24 August––5 September 1 September 
45 29 August––10 September 6 September 
43 3––15 September 11 September 
41 8––20 September 16 September 
39 14––26 September 22 September 
37 19 September––1 October 27 September 
35 24 September––6 October 2 October 
33 29 September––11 October 7 October 
31 4––16 October 12 October 
29 10––22 October 18 October 
27 15––27 October 23 October 
25 20 October––1 November 28 October 
23 27 October––8 November 4 November 
21 3––15 November 11 November 
19.4 10––22 November 18 November 
LatitudePeak in Monarch AbundanceMidpoint
49 18––30 August 26 August 
47 24 August––5 September 1 September 
45 29 August––10 September 6 September 
43 3––15 September 11 September 
41 8––20 September 16 September 
39 14––26 September 22 September 
37 19 September––1 October 27 September 
35 24 September––6 October 2 October 
33 29 September––11 October 7 October 
31 4––16 October 12 October 
29 10––22 October 18 October 
27 15––27 October 23 October 
25 20 October––1 November 28 October 
23 27 October––8 November 4 November 
21 3––15 November 11 November 
19.4 10––22 November 18 November 

While the butterfly is feeding, carefully approach from behind with the net raised and swipe the butterfly into it in one fast motion. Close your hand around the base of the net to prevent the butterfly from escaping, and gently hold the butterfly's body in place inside the net at the thorax where the legs are attached. With gloved hands, gently reach into the net and grasp the wings between your thumb and forefinger just above the thorax behind the head, holding the wings above the butterfly's body. Try to limit the amount of wing surface area you touch, to avoid rubbing off the colorful scales. The following data should be recorded on the Monarch Watch data sheet: (1) collector information, (2) data code from tag, (3) date, (4) sex of butterfly, (5) sampling location, and (6) whether the monarch is wild or was reared in captivity. Take the corresponding data tag sticker and place it firmly on the large mitten-shaped discal cell on the underside of either hind wing (Figure 3).

From the Monarch Health parasite test kit, obtain a tape sticker and gently press the adhesive side to the butterfly's abdomen (Figure 4). Press the sticker so that it wraps around the sides of the abdomen and affix it to an index card. Label each sticker sample with a number identifying the monarch from which it came (Figure 4). Detailed instructions with photographs of the process can be viewed athttp://www.monarchparasites.org. The monarch butterfly can now be released where it was originally captured by gently placing it on flowers or foliage.

Figure 3.

(A) To tag a captured monarch, gently grasp the butterfly between your thumb and index finger along the leading edge of the butterfly's forewings and locate the mitten-shaped discal cell on either hind wing. (B) Place the adhesive side of the sticker over either discal cell and carefully press the sticker down from both sides of the butterfly. Record all data and then release the butterfly close to the spot where it was captured.

Figure 3.

(A) To tag a captured monarch, gently grasp the butterfly between your thumb and index finger along the leading edge of the butterfly's forewings and locate the mitten-shaped discal cell on either hind wing. (B) Place the adhesive side of the sticker over either discal cell and carefully press the sticker down from both sides of the butterfly. Record all data and then release the butterfly close to the spot where it was captured.

Figure 4.

The Monarch Health parasite test kit is used to remove ectoparasite spores from the abdomen of each captured monarch.

Figure 4.

The Monarch Health parasite test kit is used to remove ectoparasite spores from the abdomen of each captured monarch.

Data Submission

Instructors can send in the total class data after completing the field exercise. Monarch Watch data sheets should be checked for completeness and accuracy and then mailed to the Monarch Watch Project, University of Kansas, 1200 Sunnyside Avenue, Lawrence, KS 66045. More than 11,000 Monarch Watch tag recoveries from 1994 to the present are available at http://www.monarchwatch.org via a searchable database. Students can be asked to conduct a follow-up exercise later in the year to see whether any of their tagged butterflies were recaptured and recorded.

The monarch migration rate, calculated as the number of monarchs sighted per minute, can be reported using the data sheet downloaded from the Journey North Web site (http://www.learner.org/jnorth/tm/monarch/FallDataSummary.html). This gives students the opportunity to collect ecological data related to migration through their area. Journey North also provides data sheets for reporting details about monarch habitat in the sampled area (http://www.learner.org/jnorth/tm/monarch/HabitatFallDataSheet.html). All sightings reported through the Journey North Web site are added to the system and mapped within minutes (http://www.learner.org/cgi-bin/jnorth/jn-sightings).

Protozoan spore samples from the clear tape should be labeled according to the instructions provided at http://www.monarchparasites.org. The index cards containing the labeled samples are returned to the Monarch Health Project at the University of Georgia in a pre-addressed envelope provided with the parasite test kit. Alternatively, samples can be mailed to Project Monarch Health, c/o Sonia Altizer, Odum School of Ecology, University of Georgia, Athens, GA 30602-2202. A researcher there will examine the samples under a microscope for the presence of spores of O. elektroscirrha and will inform participants of the results. The results will be mapped and provided on the Monarch Health Web site, which also provides further information and student activities related to O. elektroscirrha.

Discussion

In this lab, students participate firsthand in large-scale ecological research projects in their own community. Hands-on inquiry-based learning significantly improves elementary school students' interest and understanding of biology (Scott et al., 1998), as have citizen-science projects (Brossard et al., 2005). In my experience conducting this lab, participants, regardless of age, quickly engage in the hunting and capture of butterflies. This activity can be used to enhance the development of students' knowledge on a number of levels (Table 2). The monarch butterfly is an exciting and charismatic species that invites learning; lab participants are easily able to distinguish the sexes and apply data tags without difficulty. Providing collected data to the appropriate research projects instills a sense of pride and ownership in the scientific process, which is not often available to nonscientists. All of these activities should increase students' understanding of how scientific inquiry can be used to ask appropriate biological questions, make predictions, and seek answers through the sampling of live organisms in their natural environment. Students should be encouraged to develop solutions by linking monarch migration with the larger issue of biological conservation.

Table 1.

The major types of student knowledge promoted in this lab exercise (adapted from Anderson & Krathwohl, 2001).

Major Types & SubtypesExamples from This Lab
A. Factual Knowledge –– The basic elements students must know to be acquainted with a discipline or solve problems in it 
Aa. Knowledge of terminology Monarch butterfly, migration, parasite 
Ab. Knowledge of specific details and elements Can students describe details about monarchs' biological requirements, life cycle, migration? 
B. Conceptual Knowledge –– The interrelationships among the basic elements within a larger structure that enable them to function together 
Ba. Knowledge of classifications and categories Understanding and describing the process of animal migration through the seasons 
Bb. Knowledge of principles and generalizations What do monarchs need to survive? Why do they migrate? 
Bc. Knowledge of theories, models, and structures How might parasite infestation affect monarchs' health or their migratory patterns? 
C. Procedural Knowledge –– How to conduct methods & inquiry 
Ca. Knowledge of subject-specific skills Can students distinguish between male and female butterflies? Different species of butterflies? 
Cb. Knowledge of subject-specific techniques and methods Capturing butterflies and following the procedure to correctly tag and sample for protozoans 
Cc. Knowledge of criteria for determining when to use appropriate procedures Determining an appropriate sampling site and time of year for this lab activity 
D. Metacognitive Knowledge –– Awareness & knowledge of one's own cognition 
Da. Strategic knowledge Can students outline and summarize the issues surrounding monarch conservation? 
Db. Self-knowledge Working as a team to capture monarchs enhances students' confidence to study the scientific problem 
Major Types & SubtypesExamples from This Lab
A. Factual Knowledge –– The basic elements students must know to be acquainted with a discipline or solve problems in it 
Aa. Knowledge of terminology Monarch butterfly, migration, parasite 
Ab. Knowledge of specific details and elements Can students describe details about monarchs' biological requirements, life cycle, migration? 
B. Conceptual Knowledge –– The interrelationships among the basic elements within a larger structure that enable them to function together 
Ba. Knowledge of classifications and categories Understanding and describing the process of animal migration through the seasons 
Bb. Knowledge of principles and generalizations What do monarchs need to survive? Why do they migrate? 
Bc. Knowledge of theories, models, and structures How might parasite infestation affect monarchs' health or their migratory patterns? 
C. Procedural Knowledge –– How to conduct methods & inquiry 
Ca. Knowledge of subject-specific skills Can students distinguish between male and female butterflies? Different species of butterflies? 
Cb. Knowledge of subject-specific techniques and methods Capturing butterflies and following the procedure to correctly tag and sample for protozoans 
Cc. Knowledge of criteria for determining when to use appropriate procedures Determining an appropriate sampling site and time of year for this lab activity 
D. Metacognitive Knowledge –– Awareness & knowledge of one's own cognition 
Da. Strategic knowledge Can students outline and summarize the issues surrounding monarch conservation? 
Db. Self-knowledge Working as a team to capture monarchs enhances students' confidence to study the scientific problem 

Conservation

Although the monarch butterfly is not in immediate danger of extinction, its long-distance, multigenerational migration north and south across North America is now recognized as an ““endangered biological phenomenon”” by the IUCN. Overwintering sights in Mexico are vulnerable to destruction, as are habitat corridors along the length of the migratory flyway routes (Calvert & Brower, 1986). The North American Monarch Conservation Plan has been developed within the framework of the trinational, Montreal-based Commission for Environmental Cooperation (CEC), to promote monarch conservation in Canada, the United States, and Mexico. The main objective of the CEC is to maintain healthy monarch populations and habitats throughout the migratory flyway while promoting sustainable local livelihoods at the wintering grounds in Mexico. The Monarch Butterfly Conservation Plan provides a detailed overview of the migratory patterns, life cycle, and current conservation status of this charismatic migrant, and it can be downloaded at http://www.cec.org/monarch.

A good follow-up to this lab activity is to have the participants develop and certify an official monarch waystation through the Monarch Watch program (http://www.monarchwatch.org/waystations/). Monarch waystations are garden habitats that provide plant resources necessary for monarchs to produce successive generations throughout their long-distance migration. Milkweeds and nectar sources are declining as a result of human activity and habitat fragmentation and loss. Creating and certifying monarch waystations after the tagging exercise reinforces the importance of providing wildlife habitat and corridors in urban environments, especially for species that undergo long-distance migration. Creating and maintaining a monarch waystation can increase participants' knowledge and appreciation of ecology and the environment.

Acknowledgments

I thank the numerous Butterfly Ecology and Ecology Lab students at Clemson University, as well as David Tonkyn, for their dedicated participation in this lab activity over several field seasons. I also thank Barbara Speziale of Clemson for her support in the development of this project. Many thanks to Lisa Wagner and the South Carolina Botanical Gardens for assistance with monarch tagging and for facilitating the planting of a milkweed waystation. Finally, I thank Peter Adler and three anonymous reviewers for helpful comments that greatly improved the manuscript. This research was supported through funds from Clemson University's Creative Inquiry Undergraduate Research Program.

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