Each fall, monarch butterflies migrate south for the winter along the Atlantic coast. During that journey, they pass through Cape May on their way to Mexico, attracting many curious onlookers to see the large numbers of butterflies congregated in one place.
This year, there have been fewer monarchs than the average year, but levels are above the lowest historical years, according to Mark S. Garland, communications director for the Monarch Migration Project, which has been officially tracking the butterflies since 1991.
It’s unclear why the population has diminished, but Garland said Hurricane Sandy wasn’t a factor. “The storm arrived after almost all monarchs had departed last year,” he said. “While some coastal habitat was damaged by the storm, the plants that monarchs need are perennials that bounce back quickly.”
Garland explained that the monarch population normally cycles. “We know the overwintering population in Mexico last winter was very low, probably due to the multi-year drought in the plains and Texas. All of our monarchs are descendants of those monarchs. We also know that monarchs tend to do poorly after cool and wet spring/early summer seasons in New Jersey and the northeast, and that was true this year,” he said.
According to Garland, every few years the monarch population dips, which could be attributed to predator and parasite populations building up in the years of high monarch numbers. “The monarch enemy populations drop in the low years, perhaps paving the way for a quick rebound,” he said.
While there have been fewer monarchs this year, Cape May has still gotten plenty of visitors.
Most of the butterflies travel through Cape May before the end of October, but Garland said in a mild fall, they can be seen up to mid-November or to the first hard freeze. The Monarch Migration Project will continue its studies through Oct. 31.
Garland explained that the butterflies travel over land during their migration for safety. “Monarchs, like many other southbound migrants, prefer to stay over land rather than water, for if they grow tired over water they need to fight their way back to land in order to rest. Geography works like a funnel to concentrate monarchs into Cape May,” he said.
Louise Zemaitis, the field coordinator for the Monarch Migration Project, came up with the idea for the annual study after she visited Cape May in 1982 for the hawk migration and noticed a large number of monarch butterflies in the area. She went back several fall seasons and saw the same pattern. In 1990, she spent two weeks in Cape May to test out her theory. When she counted 77 monarchs per minute, and noticed strange flight patterns among the monarchs, she concluded Cape May would be the best location for the study. She contacted Dr. Lincoln Brower that December and they started working on the project.
The pair created the Monarch Migration Association of North America (MMANA) in early 1991. By the fall of 1991, they were ready to start the observations. It turned out that 1991 was a big year for the monarchs, with the newly formed association counting 1,759 butterflies, an average of 142.20 per hour.
WATCH VIDEO:
This video explains the Monarch Migration Project’s operations.
Since the first year, the group has changed its name to the Monarch Migration Project, has grown in size and has increased its number of hours of observation. MMP staff and volunteers count and tag butterflies each fall and also participate in educating the public. Visitors to Cape May Point State Park can participate in information sessions where they learn about the monarch’s biology, conservation and how tagging works. The organization also works with public schools in Cape May and Stone Harbor and some private schools to teach students about the butterflies.
MMP also has a blog where staff members update the public about the migration and the group’s events.