How Museum Scientists Help Urban Bees Stay Healthy

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Close-up of a bee. Bees that can be found on New York's High Line include species in the family Megachilidae.
D. Finnin/© AMNH

Stretching 1.45 miles along Manhattan’s west side, the High Line is an urban oasis, and not just for strolling New Yorkers. More than 500 species and cultivars of plants and trees grow around the tracks of this once-active elevated freight train line. And the popular greenway is also a vital year-round habitat for a diverse population of bees—which have been getting a little help from two Museum researchers ahead of the winter nesting season.

The collaboration between the Museum and the High Line began about two years ago, when entomologists Corey Smith and Sarah Kornbluth received a call from the High Line. Planning and Design manager Nicole De Feo had been interested in learning more about how the park was serving as a habitat for local bees. She turned to the Museum looking for experts.

Entomologists Sarah Kornbluth and Corey Smith netting bees on the High Line.
High Line gardeners are using recommendations from a survey of the park's bees by Museum entomologists Sarah Kornbluth and Corey to preserve existing nesting spots—and create new ones.  
D. Finnin/© AMNH

Smith, a specialist in the Division of Invertebrate Zoology, and Kornbluth, a field associate, were immediately intrigued. Though they have studied bees in places such as Wisconsin, Oregon, the southwest United States, and in France, this was a project that would have immediate, and visible, impact right in their backyard. They quickly came up with a proposal: a survey of pollinators between the spring and fall of 2017, to identify which species call the High Line home. By figuring out which species were stem-nesting, the park’s gardening team could create more nesting spots by limiting plant cutbacks and boost the resident bee population.

“A unique thing about this project is that the High Line really wanted something to come out of it—they want a healthy ecosystem in their park,” says Smith, who works with Curator Emeritus Jerome Rozen and helps manage the Museum’s extensive bee collection. “Focusing on our local bee fauna, and one locality, has been quite the departure for me.”

Starting out, Smith and Kornbluth knew that nearly half of New York’s 416 known native bee species are digger bees, or ground-nesting solitary bees, which require at least 1 foot of soil in which to burrow and lay their eggs. And while the High Line has no shortage of plants—the park’s gardens are a mix of curated beds and wild growth, conceived by planting designer Piet Oudolf to resemble the “self-seeded” landscape that overtook the elevated rails in the 1980s and 1990s—its soil beds tend to be on the shallower end. That leaves limited options for ground-nesting species. For that reason, as Smith and Kornbluth began their survey of the High Line’s bees, they found that a majority of the park’s bees are stem- and cavity-nesting species that raise their young in hollow twigs or tiny crevices.

Every other week during the six-month survey, the pair walked the High Line, usually surveying separately, beginning at its northernmost point on 34th Street and working their way south.

“Unlike other fieldwork I’ve done, collection on the High Line was a chance to interact with the public and share information with people from near and far,” says Kornbluth. “And it is a bit of a trip to be netting in a social environment.”

In addition to honey bees on the High Line, some of the most common species spotted include five of New York’s 15 yellow-faced or masked bees in the genus Hylaeus. Pollinator hotspots include the park’s wild growth area on the Interim Walkway on 31st Street, where most of the stem-nesting species were found. There may be a few reasons for this: this un-curated area doesn’t see a lot of foot traffic, nor is there plant cutback in the spring. That makes it an ideal spot for small carpenter bees, Ceratina calcarata, to bed down for the winter. “These little critters were not terribly common on the High Line, but hopefully with the altered cutback plans, we will see more of them in the coming years,” says Smith.

Bee sitting on a flowering plant on the High Line.
A majority of the bees found on the High Line are stem- and cavity-nesting species that raise their young in hollow twigs or tiny crevices. 
D. Finnin/© AMNH

Further south, flowering plants like wild tulip (Tulipa sylvestris) and prairie smoke (Geum triflorum) in the Wildflower Field and Radial Plantings on 28th Street attract bumblebees, such as Bombus impatiens. These eusocial bees are especially welcome in the park. Not only are they generalists known to fertilize nearly any flowering plant, but they also have the ability to sonicate: using their muscles, they create vibrations to loosen pollen that would otherwise be inaccessible. “This ability makes Bombus an excellent pollinator of a number of plants that honey bees tend to stay away from,” says Smith.

Smith and Kornbluth are still in the process of analyzing data, but already they have been able to make meaningful recommendations to the park’s horticulture staff. Earlier this year, staff and volunteer gardeners left undisturbed the dried stems of four different plant species, including astilbe (Astilbe chinensis) and hedgenettle (Stachys officinalis), in order to preserve nesting spots for carpenter bees. The entomologists also suggested bundling plant waste in the park’s onsite compost for bees to nest in.

“This study has helped us flesh out our knowledge of what bees are in the city,” says Kornbluth. “Sharing information about which bees live in our city and what resources they utilize could be helpful as a guideline for other parks and gardens interested in supporting wild bee populations.”

Findings from the survey are already being shared with the public and the broader community of green space advocates. An illustration included in the fall High Line magazine featured bees and butterfly species alongside their companion plants, and the park has plans to create a more extensive field guide for teachers. And in September, De Feo, Smith, and Kornbluth presented their findings from the study at the 14th annual CitiesAlive conference.

“It’s been a great collaboration with the Museum,” says the High Line’s De Feo. “We’ve learned so much about the nesting habits of our bees, and this work is really valuable to how we manage our cities and green infrastructure.”

Exhibits about honey bees and other pollinators will be a major feature of the new Susan and Peter J. Solomon Family Insectarium, part of the Museum’s Richard Gilder Center for Science, Education, and Innovation.

A version of this story appeared in the Fall issue of the Member magazine, Rotunda.