Blog

By Anna Haggenjos and Gayle Steffy

Project Overview

The Monarch Monitoring Project (MMP) was founded in 1990 by naturalist Dick Walton and Dr. Lincoln Brower. This project, under New Jersey Audubon’s Cape May Bird Observatory, seeks to better understand the fall migration of monarch butterflies through Cape May Point and along the east coast, and to educate the public and promote monarch conservation.  Today, the Monarch Monitoring Project is the longest-running research project of any migratory insect in the world.

This year, point counts performed by the MMP have expanded to include all species of butterflies and dragonflies. This will greatly increase the knowledge of insect migration through Cape May.

Monarch migration through Cape May is weather-dependent, numbers and timing vary considerably annually.  Years with predominantly east winds often push migrating monarchs from Canada and the northeast farther inland, where they can avoid the water crossings along the coast.  This is desirable for them, as studies have shown that monarchs migrating east of the Appalachians but inland have a much better chance of reaching Mexico than those migrating along the coast. Years with predominantly west or northwest winds will tend to push more monarchs to the coast, resulting in greater numbers migrating through Cape May.  Due to climate change, the monarch migration through Cape May has gotten later, but the overall trend of census data across the years appears to be relatively consistent.  This year, the road census was replaced by point counts, which should allow a more accurate comparison of monarchs migrating through Cape May from year to year.

The data obtained by the MMP from point counts and tagging provide valuable insight into the monarch migration through Cape May.  This report summarizes our point counts, tagging numbers, programs, volunteer involvement, and notable events for this year’s field season, which usually runs from September 1 to November 7.  Due to an unexpected late influx of monarchs on November 7, the 2024 point counts were extended until November 10.

Monarch Roost photo by Jack McDonough

 Research 

Point Counts: 

For over thirty years, the Monarch Monitoring Project recorded monarch migration through a road census developed by Dick Walton and Dr. Lincoln Brower. The five-mile route looks very different than when it was first implemented. Originally the census weaved through various habitat types including forests, agricultural fields, and dune systems. Today, most of Cape May Point is developed and no longer provides those diverse habitat types. This year the project transitioned from the traditional road census to stationary point counts along the dunes. This change was necessary for several reasons. Cape May exploded with tourism over the years and now the streets are full of pedestrians, bikers, cars, and golf carts. Driving at twenty miles per hour along Sunset Boulevard was becoming increasingly dangerous each year. Other than safety reasons, the census was changed to better capture migration. Higher concentrations of monarchs are observed along the dunes because they use the coast as a guideline while migrating south. Doing stationary migration counts also allows our naturalists to not only capture monarch movements but also to record the full diversity of migratory insects that are moving through Cape May on a given day. This includes, in a season, a minimum of 11 species of dragonflies, a few species of sphinx moth, and over 20 additional butterfly species.

Stationary point counts were completed three times a day, two, five, and eight hours after sunrise. These thirty-minute counts were conducted from the same dune crossing platform. During peak migration, monarchs tend to move northwest down the dune line. We counted moving monarchs in both directions from two main flight lines: one along the dunes and one behind the platform over the maritime habitat and the intersecting roadway. These counts followed a similar style and protocol to the other migratory bird counts that the Cape May Bird Observatory conducts. We also posted our counts to Trektellen.org for the first time so the public had direct access to our count information. Our project is the first to post strictly insect migratory counts to the internationally renowned website.

September was incredibly slow for monarch migration this year. For most of the month, the winds were variable from the northeast. Easterly wind components push monarchs away from the coast and further inland. While this is safer for monarchs during their migration, Cape May sees few monarch numbers as a result. In the last week of September, migration began to pick up. Peak migration this season occurred during the second week of October with the biggest day on October 7th, with around 1,500 monarchs that moved through Cape May Point throughout the day. In the days leading up to the 7th, Cape May experienced strong northwest winds that contributed to the large push of Monarchs. When the project first started, peak numbers would hit consistently in late September. Over the last few years, we have seen that their migration has shifted later into the fall, reflecting more in early-mid October. Shifting migration patterns can be attributed to climate change, as fall weather stays warmer for longer and the environmental cues that trigger monarch migration happen later and later.

The Common Green Darner is well known for its transcontinental migration in the fall. October 5th saw the peak of their migration with over 7,000 individuals counted in just thirty minutes around mid-day. In an hour and a half, nearly 30,000 passed over Cape May Point between 11:30 AM and 1:00 PM. This was the largest volume of migratory insects that we saw all season. We also recorded nearly 2,000 Black Saddlebags and over 600 Carolina Saddlebags this season.

Cloudless Sulphurs, a close second to high totals of the Monarch, were also recorded in healthy numbers this year. Their migration peaks in early fall and slowly drops off in late September. This year, we saw some consistent influxes late into the fall through early November, with a total of over 600 counted this season in raw numbers. Not a whole lot is understood about Cloudless Sulphur migration because they have not been studied as extensively as Monarchs have. However, we know that during the fall, these sulphurs disperse northward during the fall from the Southeastern US, surging up the coastal plain to as far north as Canada. Like many of our “southern” visitors during the autumn, some butterfly species, after reaching peak population numbers in late summer, disperse north in search of more habitat and food plants. This can result in butterflies slowly expanding their ranges over time.

Cloudless Sulphurs photo by Anna Haggenjos

Later into the fall, as daily temperatures start to cool and the first frosts develop to the north of us, we begin to see pushes of other brushfoot butterflies moving south with Monarchs. This typically includes species like Common Buckeyes, Mourning Cloaks, Question Marks, and Red Admirals. In the third week of October, we saw a high influx of Question Mark butterflies recorded both by our project and the Avalon Seawatch. On October 17th, we had over 20 individuals pass by Cape May Point in just an hour. 

Tagging: 

Monarch butterfly tagging provides valuable information on the routes, speed and stopover points monarchs use when migrating. Tag recoveries from Mexico have shown that monarchs migrating through Cape May Point are indeed heading to Mexico, and not off course as some scientists thought when monarch tagging began in Cape May Point.  To date, over 100 monarchs tagged by the Monarch Monitoring Project have been recovered in Mexico.

The Monarch Monitoring Project (MMP) began tagging monarchs in Cape May Point in 1992 using tags provided by Dr. Lincoln Brower. These rectangular tags were folded over the leading edge of the forewing after the scales were removed to allow for better adhesion. Eventually, these were replaced by hind wing tags distributed by Monarch Watch, which is associated with the University of Kansas. These tags are lighter, easier to apply, and more likely to be recovered than forewing tags.

Monarch Watch tags are small, circular, polypropylene tags that adhere to the rear wing of the monarch with a special adhesive. These tags are weatherproof and designed to adhere to the wing for the life of the butterfly. They weigh about 10 milligrams, which is roughly 2% of a monarch butterfly’s weight. Monarch Watch tags each have a unique alphanumeric code of 4 letters and 3 numbers and a website where recoveries can be reported. Recoveries are processed by Monarch Watch and reported in the spring.

At the time of tag application, data is taken on forewing length, wing condition, sex, and body fat, as well as time and location. When a tag is recovered, this data tells us how far and how fast the monarch traveled, and what physical characteristics may indicate better migratory success.

Tagged Monarch photo by Anna Haggenjos

The body fat and wing condition data also give us an idea of the conditions a monarch faced along its journey to Cape May. Monarchs arriving plump and in pristine condition probably had ideal weather conditions and plenty of nectar plants along their journey. Those arriving with tattered wings may have encountered storms or high winds. Monarchs arriving thin may have faced a shortage of nectar plants. Recaptures of monarchs tagged earlier at Cape May give us an idea of how fast a monarch can put on fat while stopping to rest and feed.

This season, with the help of the Monarch Field Naturalists, Field Coordinator, and our dedicated volunteers, we have tagged 3380 monarch butterflies. The overall gender ratio was 40% female and 60% male.  The average forewing length for males and females was 51.7 mm and 51.2 mm respectively.  The average fat content (measured on a scale of 1-4) was 2.4 for males and 2.5 for females.  Because of the unusual weather and late migration this fall, only 541 monarchs were tagged in September, and 345 were tagged in November.

Monarch Watch sticker tag

Roost Counting: 

When the nightly temperatures in Cape May drop in the fall, monarchs struggle to fly. Monarchs are ectothermic and therefore unable to move their muscles or keep their body temperatures up without heat from the sun. Several monarchs cluster close together on coniferous trees to survive the cold nights. Roosting is an anti-predation tactic that protects them from wind and predators. The more monarchs that gather in the same spot, the less likely that individuals will be preyed upon. It is also speculated that roosting helps keep them warmer than if they were spread out in different trees. This behavior keeps them safe and warm while they are vulnerable on cold nights.

This season saw an increased number of monarchs roosting compared to last year. In 2023, the largest roost contained just 87 monarchs at its peak. This year, two roosts formed on two consecutive nights. On October 7th, the roost on Cape and Lincoln contained 227 monarchs while the smaller roost near St. Peters had just 20. The next night, 239 monarchs roosted at Cape and Lincoln and 21 at St. Peters. This coincided with the large monarch push occurring during the first week of October. Interestingly, the roost from last year also formed at the corner of Cape and Lincoln. While this phenomenon is not fully understood, they likely visit the same sites year after year because it is the perfect roosting habitat. The Japanese black pines along the dunes provide shelter from the wind while being close to nectar sources. A high concentration of monarchs together gives off strong communicative pheromones that attract other monarchs to the area. These pheromones likely continue to attract monarchs for several days afterward, leading to roosts forming on consecutive nights. 

Outreach and Education 

Online Engagement:

For online outreach, the Monarch Monitoring Project has a Facebook and an Instagram account (both @capemaymonarchs). On our Instagram page, we gained 274 followers over the fall season for a total of 1,887. Our Instagram page also had 31,157 views on our posts with 3,026 interactions. We received 2,508 likes on our posts. The social media audience is evenly distributed between ages 35-44, 45-54, and 55-64. Only 0.7% of Instagram followers are teenagers between 13-17, which suggests that more effort should be put into reaching younger generations. Between September 1st and November 20th, there were 1,045 visits to our profile.

We engage with a wider audience on Facebook than we do on Instagram. We had over 313,000 organic engagements with our content on Facebook with 19,900 visits to our profile. We gained 584 new followers on Facebook this fall, currently totaling 8,841 followers. On both platforms, a majority of our followers are women, with over 80% of our followers on both platforms being women. 

In-person Engagement: 

The Monarch Monitoring Project aims to educate the public about monarch migration, conservation, and ecology. People cannot care about the conservation of a species without first having an appreciation for it. This is why so much of the project’s efforts focus on public education. We held public tagging demonstrations at the state park on Fridays, Saturdays, and Sundays. These demos lasted about an hour with a thirty-minute talk about the project’s history, our research, monarch biology, and migration, and ended with tagging. We handed out free milkweed seeds to visitors along with educational pamphlets about wildlife gardening. These talks stressed the importance of providing habitat for butterflies and what the average person can do to help the monarchs. Additionally, we held two “drop-in” programs at 10:30 AM at the Nature Center of Cape May on Mondays and at Triangle Park in Cape May Point on Wednesdays. The annual Monarch Fest at NJ Audubon’s Nature Center of Cape May on September 29, 2024, saw over 1,000 visitors. We conducted our demos educating the public on our work and Monarch conservation every 1.5 hrs. and had approximately 500 visitors at these demos throughout the day. Our NJ Audubon Fall Festival was also a big success with hundreds of visitors over 3 days, in which we did one demo per day at noon. Visitor numbers for September and October are summarized below.

Volunteer Numbers: 

We are very grateful for the wonderful support from our dedicated volunteers and staff. In total, the Monarch Monitoring Project volunteers put in 187 hours assisting with programming, tagging, and inputting data this fall. We’d like to thank our amazing volunteers Marg Salvia, Jayne Branigan, Jan Zimmerman, Betty Ross, Maya Clark, Wendy Ford, Patsy Eickelberg, Diane Tassey, Louise Zemaitis, and Mark Garland. Between 10 volunteers tagging, assisting with programming, and or entering tag data. Additionally, we want to say a special thank you to our returning Field Coordinator, Jack McDonough, and our returning Monarch Field Naturalists, Anna Haggenjos and Gayle Steffy, for all their hard work and support this season.

Thank you all for an incredible season and the Monarch Monitoring Project is looking forward to another year of continuing our education, research, and conservation efforts!