How Citizen Scientists Help National Parks Catch Ecological Threats

National park visitors are collecting valuable biodiversity data with mobile apps such as iNaturalist and eBird. Their observations — far more than park staff and outside scientists could ever gather themselves — help managers spot and respond to threats early. Three parks show how.

Saguaro: the race to stop stinknet

In 2020 the Aguila Fire burned more than 800 acres of northern Phoenix in Maricopa County, Arizona, scorching Sonoran Desert plants including saguaro cactus (Carnegiea gigantea). In its wake the burned ground was taken over by stinknet (Oncosiphon pilulifer, also called globe chamomile), a southern African plant that has spread quickly through California and Arizona since it was first seen on the West Coast in 1981.

Stinknet has yellow, petal-less flower heads and carrot-top-like leaves, grows from about six inches to two feet tall, and gives off a turpentine smell when crushed. A single pea-sized flower head can make up to 100 tiny seeds that travel on wind, water, vehicles, shoes and clothing. It crowds out native plants that feed and shelter wildlife — such as Parry's penstemon (Penstemon parryi), a pink wildflower favored by hummingbirds — and can cause headaches, rashes, blisters and severe breathing reactions in sensitive people. Dry stands fuel wildfires with caustic smoke.

Around Phoenix it is now nearly impossible to manage. In southern Arizona there may still be time. Tucson's first patch was spotted in 2015, and having watched stinknet explode elsewhere, Saguaro National Park, Tucson Audubon and other groups joined forces. "One of the rules for invasive plants is that if you can nip these invasions in the bud when they're just starting, you'll have a lot more success over the long run," said Saguaro biologist Don Swann. Saguaro botanist Dan Beckman added that the job was too big for a small group: "it's clear that we need the whole community involved."

They launched stinknet.org, where people report patches with a location and photo that feed an online map; in the 2024 season alone it received almost 2,500 reports. Park crews use the map to remove stinknet and return in later years to check for regrowth — work that would be impossible without reports from visitors and residents. Outside the park, residents are encouraged to pull it themselves, wearing gloves and a mask and sealing the plants in a bag. Tucson Audubon's invasive-plant manager points out that while eradication isn't possible, each plant pulled removes thousands of plants from the next year's population.

Removing stinknet at Saguaro National Park. NPS/Dan Beckman.

Park biologists consider stinknet the most dangerous invasive plant in the area since buffelgrass (Cenchrus ciliaris) arrived in the 1930s.

Boston Harbor Islands: BioBlitzes

Other parks need broad biodiversity data to follow change over time. BioBlitzes challenge volunteers to document as many species as they can in one area over a short time, and at the National Parks of Boston self-guided and ranger-led BioBlitzes feed an ongoing survey of Boston Harbor Islands National and State Park. The Park Service is also working with Wild Spotter to engage the public in early detection of invasive species.

Participants use iNaturalist to identify pollinators at a Boston Harbor Islands BioBlitz. NPS Photo/E. Bernbaum.

Since 2017, the University of Massachusetts Boston's Honors College has built a BioBlitz into its fall orientation: groups of about 100 incoming students spend a two-day retreat on Cathleen Stone/Thompson Island and, guided by rangers, survey its meadows, forests, salt marshes and beaches for three hours. The college's associate dean describes it as students' first hands-on taste of citizen science and a new way of seeing their city.

Can first-time users collect good data? Researchers at UMass Boston and Suffolk University reviewed more than 2,000 observations and 5,700 photographs from three years of the island's BioBlitzes and concluded in 2021 that they can: the students' iNaturalist records were reliable and usable for biodiversity research.

Students have recorded hundreds of species, including invasive European green crabs (Carcinus maenas) and Asian shore crabs (Hemigrapsus sanguineus), a growing threat to New England coasts — and, in 2019, the island's first and only record of DeKay's brownsnake (Storeria dekayi).

Volunteers at a Bivalve Quest, another citizen science activity at Boston Harbor Islands. NPS Photo/E. Bernbaum.

Citizen science isn't the right tool for every problem — the park tracks land lost to erosion and sea level rise by remote sensing — but for knowing which species live where, the public is invaluable. "If a project is proposed, we can draw a map around the area on iNaturalist and see what observations were there," said Marc Albert, who directs science and stewardship partnerships at the National Parks of Boston. Managers can, for example, favor areas with more native species when planning invasive-plant treatment, and over time track how climate change is affecting biodiversity.

Sunset at Boston Harbor Islands National and State Park. NPS Photo.

Acadia: turning data into early warnings

Since 2003 the public has recorded more than half a million observations of plants, animals and fungi in Acadia National Park and about 16,000 at Katahdin Woods and Waters National Monument. With National Park Foundation funding, Schoodic Institute, an Acadia partner, spent two years building automated tools to deliver those findings to managers. Every Monday, park managers and science staff get a digest of the past week's iNaturalist and eBird records for 180 species of management concern, sorted into pests and invasive species, threatened and endangered species, rare species, and species new to the park.

Removing invasive purple loosestrife from a wetland at Acadia National Park. NPS Photo.

With nearly 50,000 acres to watch, Acadia's vegetation team can easily miss the start of an infestation. "Many of our forest pest observations in new areas have come from residents of the community," said vegetation program manager Jesse Wheeler. The team visits reported sites within days: a lone Japanese barberry shrub is quick to remove, but once pests or pathogens take over a stand of trees, managers can only monitor and slow them.

One emerging threat is the hemlock woolly adelgid (Adelges tsugae), a tiny, aphid-like invasive insect that has devastated eastern hemlocks (Tsuga canadensis) across the eastern United States and Canada, including in Great Smoky Mountains and Shenandoah national parks, and can kill large trees in as little as four years. Its arrival in Acadia was confirmed in 2022. It shows up as small white cottony masses under hemlock branches, and visitors who report it on iNaturalist help the park track it and decide on steps such as trimming branches that touch people, pets and vehicles. Schoodic Institute's weekly report is designed to be usable by other parks too.

Next time you're outside, log what you see. A pretty flower may be an invasive species; a hemlock may be showing the first signs of adelgid; an unfamiliar insect may be the first of its kind in your area.

Sources

• Nina Foster, 2024 Scientists in Parks intern at Acadia National Park: "Citizen Science Data Inform Park Managers of Ecological Threats," National Park Service. The article spells the snake's species name "dekay"; it is corrected to dekayi. Photographs credited to Schoodic Institute, the Arizona Department of Forestry and Fire Management and Pima County are not reproduced.