A Research and Education Project of New Jersey Audubon’s Cape May Bird Observatory
The Monarch Monitoring Project (MMP), established in 1990, is a research and education program focusing on the fall migration of monarch butterflies along the Atlantic coast. For over two decades the MMP has gathered data on monarchs moving through Cape May during September and October. MMP staff and volunteers also conduct informational programs on monarch biology and tagging.
Imagine an insect weighing less than a paper clip beginning a journey in Scarborough, Maine in late August. If successful she will arrive at the over-wintering grounds high in the Transverse Neo-Volcanic Mountain Range in Michoacan, Mexico in October, completing a journey of over 2500 miles. This amazing migration of the monarch butterfly is still mysterious to us, and there are many questions left to explore.
The Monarch Monitoring Project’s (MMP) overall goal is to increase our understanding of the fall migration of monarchs along the Atlantic coast, through both research and education. Ultimately, it is our hope that these efforts will improve the knowledge and awareness of these remarkable butterflies so that populations of migrant monarchs will enjoy a secure future.
The Cape May Point Road Census is conducted three times per day from September 1st through October 31st. Rather than trying to count all the monarchs moving through Cape May, our methodology uses sampling criteria which result in data reflecting relative annual numbers. Counts are made by a single observer driving a car approximately 20-25 mi. per hour along a 5 mile route. All monarchs observed are tallied but no stops are allowed to count specific concentrations. The route passes through a variety of habitats including southern hardwood forest, agricultural field, brackish wetland meadow, suburban neighborhoods, and coastal dunes along the Atlantic Ocean and Delaware Bay. Annual summaries include yearly data for the Road Census.
Education has always been an important part of the MMP. Our most popular programs are the informational sessions we offer at Cape May Point State Park, where locals and tourists of diverse backgrounds are fascinated by the monarch migration. MMP staff and volunteers talk to thousands of these visitors each year, sharing the basics of monarch biology, conservation, and (everyone’s favorite) how to tag monarch butterflies.
In addition to public tagging demonstrations, MMP staff also works with educating school groups across Cape May County, both in the classroom and in the field. MMP has worked with The Nature Center of Cape May for class field trips, Monarch Fest, and summer programs.
A critical aspect of MMP educational efforts is data sharing with other projects, such as Monarch Watch and Journey North. Tags are distributed to us by Monarch Watch, and we report back with our tagging data. Notable migration days and large roosts are reported to Journey North.
Publications are an important piece of our educational work. MMP staff have written popular articles for American Butterflies and CMBO’s Peregrine Observer. Our project has also been the focus of articles in Journal of the Lepidopterists’ Society, Annals of the Entomological Society of America, and Journal of the Kansas Entomological Society. In 2006 we produced the DVD Cape May – Fall Flight.
Prior to 1975, Western science had not discovered where North American monarchs spent the winters. This great natural history mystery was finally solved by Ken and Cathy Brugger, working in collaboration with Fred and Norah Urquhart. On January 9th 1975, they discovered the overwintering site for monarch butterflies high in the mountains of central Mexico.
Over the following two decades, researchers, including Lincoln Brower, have contributed greatly to our knowledge of the monarch migration puzzle. Although the overwintering site was discovered in central Mexico, it was still unclear whether the Atlantic coast monarchs could make it that far. Urquhart suggested this group might be “aberrant,” moving south along the Florida peninsula, ultimately over-wintering in the Yucatan or some other unknown location to the south. When the MMP began field work in 1991, it was widely assumed that the Atlantic coast migrants overwintered in Mexico, so an early goal of the MMP was to settle this debate.
Although MMP workers initially tagged less than 1000 monarchs per season, a 1994 MMP tagged monarch recovered in Temple, Texas pointed toward the Mexican hypothesis. In 1995, Gayle Steffy, our research intern and veteran monarch worker, set new benchmarks for our efforts by tagging over 5000 monarchs.
Following Gayle’s lead, we redoubled our tagging efforts in subsequent years. The payoff came in 1998 when 7 of our tagged monarchs were recovered at the El Rosario site in Mexico. Details of MMP recaptures both along the migratory route as well as in Mexico can be found in the annual summaries.
Counting Monarchs in Cape May for Over A Quarter Century
Table #1 Each yearly column shows the average number of monarchs seen per hour for each of the nine* census weeks. The final cell in the yearly column is the average number of monarchs seen per hour for that year over the entire season.
Table #1. CAPE MAY POINT ROAD CENSUS 1992-2018
Brower, L., Taylor, O.,Wiliams, E., Slayback, D., Zubietas, R., Ramirez. 2011. Decline of monarch butterflies overwintering in Mexico: is the migratory phenomenon at risk? The Royal Entomological Society, Insect Conservation and Diversity.
Davis, A. 2011. Are migratory monarchs really declining in eastern North America? Examining evidence from two fall census programs. The Royal Entomological Society, Insect Conservation and Diversity.
Brindza, L., Brower, L.P., Davis, A.K. & Van Hook, T. 2008 Comparative success of monarch butterfly migration to overwintering sites in Mexico from inland and coastal sites in Virginia. Journal of the Lepidopterists’ Society, 62, 189–200.
Gibbs,D., Walton, R., Brower, L., and Davis, A. Monarch Butterﬂy (Lepidoptera: Nymphalidae) Migration Monitoring at Chincoteague, Virginia and Cape May, New Jersey: A Comparison of Long-term Trends. 2006. Journal Of The Kansas Entomological Society 79(2), 2006, pp. 156–164.
Walton, R., L. P. Brower, and A. K. Davis. 2005. Long-term monitoring and fall migration patterns of the monarch butterﬂy (Nymphalidae: Danainae) in Cape May, NJ. Annals of the Entomological Society of America 98:682–689.
Walton, R. and L. Brower. 1996. Monitoring the fall migration of the monarch butterﬂy Danaus plexippus L. (Nymphalidae: Danainae) in eastern North America: 1991–1994. Journal of the Lepidopterists’ Society 50:1–20.
Brower, L. 1995. Understanding and misunderstanding the migration of the monarch butterﬂy (Nymphalidae) in North America: 1857–1995. Journal of the Lepidopterist’s Society 49:304–385.
Staff & Personnel
Field Naturalist Intern
Field Naturalist Intern