The Improbable Migrations of Insects
Monarch butterflies on seaside goldenrod
Every fall in Cape May means one thing: It’s time for the great migrations of wildlife headed south to warmer climates and abundant food. Cape May sits in one of the world’s great migration corridors, and in addition to being on one of these great highways, the narrow peninsula between the Atlantic Ocean and Delaware Bay is also a stopover point. Think of it as a great truck stop on an interstate system. The abundant beaches, farms, meadows, and forests of the peninsula are a perfect place for migratory wildlife to rest and refuel before making the first of many dangerous crossings over open water.
Most people are familiar with the globally famous fall migration of eagles, hawks, and falcons through Cape May, and spending time at the Hawkwatch Platform in Cape May Point State Park on a sunny fall day with a good north wind is a rewarding venture. Perhaps fewer are familiar with the great southbound migration of seabirds that occurs just offshore of Cape May.
The Seawatch on the north end of Avalon is where scientists count the strings of nearly a million seabirds migrating south from their North Atlantic breeding areas. Because these birds are spread over large areas and spend so much time out at sea or nesting on isolated rocky offshore islands, understanding their populations and population trends is extremely difficult. One of the best ways to do that is to monitor them as they are funneling past Seven Mile Beach.
The north end of Avalon juts almost a mile farther out into the Atlantic than the rest of the barrier islands, bringing mixed flocks of migrating birds within view of the beach. More than 60% of all sea ducks breeding in the Western Atlantic pass by or winter off of Seven Mile Beach, making Avalon Seawatch one of the greatest natural spectacles in North America. If you are here this fall, take time to stop by. Maybe you will witness a peak day when more than 50,000 seabirds will pass by.
Perhaps less well known but equally fascinating is that Cape May is also a migratory flyway for insects. Cape May is an important stopover for monarch butterflies as they make their way south to the mountains of Mexico to spend the winter. By early November, most of the monarchs have moved through, but lingering sunny and warm days will still reveal a few headed south.
Butterflies (and some moths) migrate to avoid unfavorable circumstances that can range from weather, food shortages or even overpopulation. Just like birds, migration in butterflies and moths can involve all individuals of a species or just a subgroup of the individuals. The most well-known migration is that of the eastern population of monarch butterflies. Several other species of butterflies and moths are also migratory. The painted lady, common buckeye, American lady, red admiral, cloudless sulphur, numerous skippers, question mark, and mourning cloak are all butterflies that migrate, and many can be seen in the area nectaring and roosting as they pause on their long journeys.
Unlike birds, insect migrations are typically only one-way journeys because of their short lifespan. The gardens at The Wetlands Institute and the Stone Harbor Bird Sanctuary are great places to see butterflies during migration. In fact, the gardens at the Stone Harbor Bird Sanctuary are certified monarch habitats, designed and planted to provide resources to migratory butterflies. If you time it right, the seaside goldenrod that covers the dunes at Stone Harbor Point with beautiful yellow flowers in late fall can be covered with monarchs.
Of all the remarkable migrations, the migration of dragonflies is perhaps the least well-known, both to the general public as well as the scientific community. Several species of dragonflies are known to migrate and many can be seen in Cape May in the late summer and throughout the fall. The warm weather that persists through the end of October keeps dragonflies in the area, with several being seen into November.
The wandering glider is a powerhouse. It has been touted as the most evolved dragonfly in the world. It drifts on the wind and feeds on windborne insects until different temperature air masses converge and produce rain pools where it breeds. Wandering gliders can fly day and night over the open ocean for thousands of miles. In North America, they straggle north to breeding areas, and like the monarch, their offspring migrate south in the fall. The wandering glider breeds on all continents except Europe, and is the only dragonfly found around the world. Thanks to its ability to fly long distances over open water, it is also the only dragonfly found on oceanic islands. These yellow-orange, clear-winged marvels are less than 2 inches long and are strong fliers, constantly hovering 8-to-10 feet off the ground and only rarely perching. They are commonly seen at The Wetlands Institute hunting over the meadows.
Several other dragonflies can be seen migrating through Cape May. The black saddlebags is common. It is a medium-sized dragonfly (2 inches long) with a black body, clear wings, and distinctive black “saddlebags” markings on the wings next to the body. There are both resident and migratory populations of black saddlebags. You can see them in swarms during the southbound migration in the fall. They too are regular visitors to The Wetlands Institute.
Other known migratory dragonflies seen in the Cape May area in the fall are the twelve spotted skimmer, common green darner, swamp darner, and red saddlebags. The small blue dasher is a frequent swarmer on The Wetlands Institute Salt Marsh Trail in early fall as well. It appears suddenly in large numbers and feeds over the marsh, perching on the trail vegetation for several weeks before disappearing again. Documentation of migratory behavior in blue dashers is relatively limited and mostly related to congregating behavior at the appropriate time for migration rather than actual evidence of migration.
Cape May during fall migration is a special place. The peninsula’s location makes it part of an important flyway and its rich diversity of habitats and protected environments is a key reason that it has become and remained such an important migratory stopover. There are challenges. Development and habitat loss continues to be a concern. Invasive and non-native vegetation is also taking a toll. When birds and insects make their stopovers, they are in desperate need of rest and food to power them on their journeys and successfully reach their destinations.
There is a lot you can do. Maintaining native plants in gardens and managing invasive plants on your property are two great ways to help. Making your patch of land welcoming and suitable for these travelers will not only put out the welcome mat so you can enjoy their visits, but it also gives them a helping hand along the way. There are lots of resources to help you plan garden improvements. The National Wildlife Federation has programs for creating backyard habitat and provides great resources for getting started. The Wetlands Institute has gardens that are promoting native plants for pollinators and wildlife, and hosts periodic programs where you can see native plants in action. The Stone Harbor Bird Sanctuary gardens help you see native plants in action, and the website has lots of information on the plants in the gardens. Get out there and witness the marvel of what this place has to offer. It’s special, indeed!
