Local groups work to stop the spread of invasive plant species on the East End

For thousands of years, plants and pollinators on the North Fork have evolved together, and their relationship has been mutually beneficial. But in the last few centuries, some of the greenery that makes the North Fork so picturesque has become a danger to birds, bees, butterflies and other pollinators. Experts say there is now a long list of non-native plants that have been introduced to the local landscape, often by gardeners who may not know that the exotic plant they just bought is part of the problem. 

Three area organizations have been working collaboratively to get the upper hand on this troublesome vegetation: Hallockville Museum Farm, North Fork Audubon Society and North Fork Pollinator Pathway group. 

“Step one is to remove non-native invaders,” said Christine Killorin, who oversees the Habitat Project at Hallockville. “These aggressive plants have no natural pests. They’re not seen as food by our pollinators. Non-natives don’t do anything for the environment. There’s less space for indigenous plants because the invasives crowd them out and take over.”

Ms. Killorin pointed out that most insects have a specialized food strategy, meaning they eat only one or two plants and cannot adapt to crunching on foreign foliage. So when native plants disappear as large swaths of land are cleared for development, many species struggle to survive. When that problem is compounded by the introduction of non-native plants, there is even less food for pollinators, she said.

One species in particular tops the invasive list at Hallockville’s Habitat Project, and it’s one that many residents assume is indigenous because of its ubiquity on the North Fork: the yellow and white flowered Japanese honeysuckle, an invasive plant that strangles trees and shrubs. At Hallockville, it has been replaced with a native variety of honeysuckle, Lonicera sempervirens — or “Major Wheeler” — which has orange and red blossoms. 

Ms. Killorin has been uprooting the non-natives on her own property. “I feel so good about it,” she said. “I see more butterflies and birds in my yard.” 

Robin Simmen, a North Fork Audubon Society board member, said she’s been working on this challenging problem ever since it became evident to her while walking one day at Inlet Pond County Park in Greenport, which was farmland until the mid-1950s. The park was rapidly losing its native plant palette because it was being overwhelmed by privet shrubs, a popular property hedge across the North Fork. “The park was a tangled hot mess of invasives. Privet was choking the trails that went down to the Sound. The park and its soil were being terribly degraded,” Ms. Simmen said. “The invasives are destroying the native environment that our wildlife depends on.” Privet seed spreads through bird droppings and grows rapidly, outpacing many indigenous plants, and leading to die-offs.

Beginning in 2017, volunteers replaced 600 square feet of non-native lawn In front of the park’s Roy Latham Nature Center with a rain garden. “It’s now thriving and filled with more than 60 species of native plants,” Ms. Simmen said. “The garden is solely irrigated by roof water and flutters with butterflies, bees and moths. Landscaping with native plants restores the entire food chain for wildlife. If we’re choosing to grow invasive plants or barren turf, we completely disrupt the food cycle and our birds and insects begin to die off.” 

Since 2021, North Fork Audubon Society volunteers have removed more than 12,000 privets along the trails at Inlet Pond Park, “which is astonishing,” Ms. Simmen said. 

Other hostile invasives include the mile-a-minute weed and oriental bittersweet vines and the multi-flora rose, a non-native bush that is particularly harmful to migratory birds as it destroys their temporary habitats and food sources. 

Although invasives also attract pollinators, which in turn help them to spread, the broader ecosystem continues to suffer. “Think of it as potato chips versus a real potato,” said Nancy DePas Reinertsen, co-chair of the North Fork Pollinator Pathway, “There’s not as much nutritional value for the pollinators, but it’s still yummy.”

Ms. Killorin explained that “butterflies and bees will seek nectar from some nonnatives, but they do not provide what the pollinators need, such as the food for the eggs to hatch on. For example, a Monarch butterfly will take nectar from lots of plants, but milkweed is the only food their eggs can develop on.”

So what can be done?

“We’re asking the Town of Southold for a grant to buy more native plants,” Ms. Killorin said. She added that invasives can change the DNA of the native plant, enabling them to effectively overtake an entire area in just a few seasons. 

A few miles west of the North Fork Audubon Society gardens is the semi-circular meadow at Custer Preserve in Southold. According to Ms. DePas Reinertsen, it is the victim of wildflowers that were planted there, undoubtedly with the best intentions, about 30 years ago. “The tall spiked purple lupines look amazing in spring, but were the wrong seeds to put in because they are an aggressive, invasive species, not the more delicate, smaller North East native Lupinus perennis,” she said. “No one knew the far-reaching problems that would be created by scattering wildflower seeds from another area of the country til just recently.” 

The Town of Southold has been notably forward-thinking with the Custer Preserve project. The Southold Peconic Civic Association’s environmental advisory committee, of which Ms. DePas Reinertsen is a member, partnered with the town to select the location for its high visibility and the many invasives that needed to be cleared. A grant from ReWild LI provided design, irrigation and several ecotypic plants. The town continues to provide funds, mulch and cardboard, and volunteers will continue working for at least five years until the meadow is completely cleared of invasives. 

Many volunteers are needed next month to plant at the meadow at Custer Preserve. Contact [email protected] for more information. Pollinator Pathway is also partnering with the North Fork Audubon Society to host a Native Plant and Seed Swap in late October. For more information, check social media or email [email protected].

Ms. Killorin encouraged North Fork residents to “plant an oak tree in your yard. If you do that, you’ve done something important. And please, do not cut down mature oak trees.”