Pollinators in Peril? Surveying Native Bees in 46 National Parks

Can you name five bees in your nearest park? Ten? Will they still be there in 50 years? Pollinators keep ecosystems healthy, from almond orchards to wild mountain meadows, and the decline of the honey bee is well known. But far less was known about the diversity and resilience of the native bees in America's national parks. A study reported in the National Park Service's Park Science set out to change that.

Why bees, and why these habitats

Many flowering plants in the parks depend on insects to reproduce, and native bees are almost always the most efficient and varied of those pollinators: 3,604 species have been described in North America north of Mexico, with perhaps 400 more yet to be named. Bees face habitat loss, pesticides, introduced parasites and invasive plants and insects — and climate change, which could push their ranges upslope or northward, shrink populations, and throw the timing of flowers and pollinators out of step.

The bee communities most at risk, including rare and endemic species, live in habitats most exposed to warming, shifting climates and rising seas: high-elevation meadows, inland deserts and coastal dunes — many of the parks' most iconic landscapes. The parks' variety makes them an ideal natural laboratory for studying where bees live and how climate change might affect them.

The study

In 2010, researchers from the National Park Service (Ann Rodman of Yellowstone), the U.S. Geological Survey (Sam Droege and Ralph Grundel) and Harvard University (Jessica Rykken) won funding from the Park Service's Climate Change Response Program. Their goals were to:

• compare bees in "vulnerable" habitats with those in paired "common" habitats typical of the surrounding landscape, to see whether vulnerable habitats hold a distinctive — and more threatened — bee fauna;
• tell each park about its bees, including rare and endemic species, and suggest ways to protect bee habitat;
• raise awareness among park staff and visitors of native bees and the threats they face.

The 46 parks in the National Park System that took part in the bee inventory (NPS).

Bee bowls

Sampling was kept simple, cheap and volunteer-friendly. Each park chose a vulnerable site and a common site and sampled each five times, from the first spring flowers to the end of the fall bloom. At each site, 30 "bee bowls" painted blue, yellow and white to look like flowers were set out 5 meters (16 feet) apart. Bees that landed were trapped in soapy water; ideally the bowls stayed out for 24 hours of calm, sunny weather. The catch was strained, bagged and shipped for identification.

Straining the catch from a "bee bowl"; the contents of all 30 bowls on a transect were combined and shipped to the bee lab in Maryland (NPS photo).

Collecting was the easy part. Preparing, identifying and cataloging tens of thousands of specimens, drawn from a pool of several thousand possible species from Alaska to Maine and California to Florida, was the real challenge. USGS biologist Sam Droege's Bee Inventory and Monitoring Lab at the Patuxent Wildlife Research Center in Beltsville, Maryland, processed them all, with help from high school and college students, and identified most eastern bees; most western bees went to the U.S. Department of Agriculture's Bee Biology and Systematics Lab in Logan, Utah.

The USGS Bee Inventory and Monitoring Lab (USGS).

Many remarkable bees

The 46 parks — 30 national parks, preserves and monuments, 10 lakeshores and seashores, and 6 recreation areas, historical parks and parkways, from Alaska to the Virgin Islands — ran 809 bee-bowl transects and collected more than 43,000 bees from 2010 to 2013. So far more than 25,000 have been identified, representing 43 genera and about 685 species; many western identifications await scarce specialists.

• The widespread. The non-native honey bee turned up in large numbers in half the parks. The most-collected bee of all was Augochlorella aurata, a brilliant green sweat bee: 2,012 individuals (4.6% of the total) in 17 parks from Big Thicket, Texas, eastward — likely a pollination workhorse in eastern parks.
• Dune specialists. More than 1,000 Lasioglossum marinum, a coastal dune specialist, were found in seven parks from Boston Harbor Islands to Biscayne. Rarer specialists included the polyester bee Colletes brevicornis, found only at Assateague Island's dunes, and the mason bees Dianthidium simile and Osmia michiganensis on Great Lakes shores. These species suggest dunes hold a distinctive bee fauna — one at risk if lake and sea levels change or storms like Hurricane Sandy reshape the coast.
• Desert and mountain finds. A digger bee, Habropoda pallida, at Mojave is a desert dune specialist thought to depend on creosote bush. A tiny mining bee, Perdita albihirta, turned up at Petrified Forest. Two specimens from Santa Monica Mountains resemble a cactus bee but are likely an undescribed species. And at Canaveral National Seashore in 2013, researchers collected the southeastern polyester bee Colletes titusensis, with no collection records since 1938.

Arid dune pollinator habitat at Mojave National Preserve (left) and interns setting bee bowls in a high-elevation meadow at Yellowstone (right). NPS photos.

Left: the tiny mining bee Perdita albihirta geraeae from Petrified Forest, just a few millimeters long. Right: Colletes titusensis from Canaveral National Seashore. USGS Bee Inventory and Monitoring Lab.

Next steps

Once complete, the database of more than 43,000 bees will be the largest replicated survey of native pollinators anywhere in the world. It will let researchers compare vulnerable and common habitats within parks, test whether similar habitats share bees across regions (a "dune signal" rather than a "park signal"), and identify the environmental and climatic factors shaping bee communities. Climate summaries for each site, comparing past, present and projected conditions, will help predict which species may persist. The survey also sets a baseline for long-term monitoring, with methods any park can repeat.

Spreading the buzz

Parks enlisted interns, volunteers and citizen scientists — Virginia Master Naturalists at George Washington Birthplace, college and youth-program students at Santa Monica Mountains and Channel Islands, Student Conservation Association and Youth Conservation Corps volunteers in Yellowstone. Each park will get a two-page resource brief on its bees, with species data in the NPSpecies database. Droege's lab has built a low-cost camera setup for magnified bee portraits, hundreds of which are free for educational use, and the project helped fund free Bee Observer Cards from the Encyclopedia of Life and Harvard's Farrell Lab.

Parks are already acting on what they learned: interpretive programs on native bees at Fire Island, new transects at Organ Pipe Cactus to study the bees of an endangered cactus, and a college intern at Isle Royale extending collections. "Prior to the study we knew of only a handful of bee species on the island…now we are aware of over 60 species," said Paul Brown, Isle Royale's chief of natural resources.

Sources

• Rykken J, Rodman A, Droege S, Grundel R. "Pollinators in peril? A multipark approach to evaluating bee communities in habitats vulnerable to effects from climate change," Park Science 31(1), Special Issue 2014, National Park Service; citing Grundel and others (2011).