Johanna Vietry visits the dinghy planters installed along the Newport Harbor Walk every day with one thing in mind: monarch butterflies. The president of Friends of the Waterfront and a URI master gardener, she is hoping that the nation’s best-known butterfly will show off its black-and-orange colors and sip nectar from the abundant blooming flowers in the planters.
“There wasn’t any vegetation to encourage monarchs to visit the waterfront until we planted native plants there,” Vietry said. “Now I’m checking my monarch boats every day, and I keep seeing them.”
She isn’t the only one. Monarch numbers appear to be on the rise after their global population crashed in 2013 due to what some experts say was a combination of illegal logging
Mexican forests where they overwinter, changing climate patterns, and declines
in milkweed plants on which the butterfly caterpillars feed.
|Monarch butterfly on thistle (Dave Hansen)|
Mark Pagliarini, an environmental educator at the Norman Bird Sanctuary who describes himself as “a bug enthusiast,” conducts regular butterfly surveys of the area and pays attention to national butterfly trends. He said this year has been an especially good one for monarchs.
“On and off Aquidneck Island, and in the U.S. as a whole, there is a noticeable increase in monarch activity,” he said. “On the island, there are definitely more monarch individuals around, and I’ve seen plenty of eggs and lots of monarch caterpillars.”
Marty Wencek agrees that monarch numbers are up this year, but he isn’t ready to say that the insects have recovered from their population decline yet. A biologist at the R.I. Department of Environmental Management and an avid butterfly observer for 55 years, he remembers the years when he would see hundreds of monarchs in a day along the coast in the fall. He is worried that pesticide use and continued development of the fields where they feed and breed will keep monarch populations low.
Wencek also said that monarchs are particularly affected by the spreading of black swallow-wort, an invasive vine that kills any monarch caterpillars that eat its leaves.
What their abundance this year means for the future is uncertain, however, because monarch populations naturally rise and fall with regularity.
“Populations do fluctuate as a matter of course, but it always makes one get a sincere feeling of concern when such an event occurs, and a feeling of relief when they thankfully rebound,” Wencek said.
Monarchs in the Northeast engage in a four-generation migration each year. They depart in the fall on a 3,000-mile migration to Mexico to hibernate in oyamel fir trees. In March, they head back north stopping along the way to lay their eggs. When those eggs hatch and the caterpillars become butterflies, the new generation continues the migration, arriving in the Northeast in July, whereupon they lay their eggs and die. One generation later the cycle begins again.
According to David Gregg, director of the Rhode Island Natural History Survey, research suggests that many monarchs from the Northeast may get delayed or even stuck in the Southeast during migration and never make it to Mexico.
“So it may be that Rhode Island and the rest of the Northeast is sort of a monarch population sink,” he said.
On the other hand, Gregg added, “with climate change, things could change. One possibility is that with slightly milder temperatures in the Southeast, perhaps those dead-end monarchs from the East Coast will develop into a full-blown over-wintering population. That's just speculation at this point, but it shows how much things could change with climate change.”
Because monarch caterpillars rely on milkweed, many conservation efforts in recent years have focused on encouraging people to plant native milkweed wherever possible. And if the growing numbers of monarchs in the area are any indication, it seems to be working.
But Gregg and Pagliarini said that it may be even more important to plant native flowers from which adult monarchs can feed.
“The availability of suitable nectar sources towards the end of the season” is especially important, Gregg said. “The implication for us in Rhode Island is that we should be concentrating at least as much energy on planting goldenrods, asters, and joe-pye weeds, especially along the coast, as we do on planting milkweed patches. This would also be among the most important things we could do for pollinators generally, so it really is a great place to put our effort.”
Pagliarini said that those looking to observe and photograph monarchs on Aquidneck Island should consider visiting Norman Bird Sanctuary, where he is helping create a pollinator field to attract butterflies, Sachuest Point National Wildlife Refuge, and Brenton Point.
This article first appeared in the Newport Mercury on August 16, 2017.