Todd McLeish: The decline of other N.E. pollinators

Rusty patched bumblebees, listed on the U.S. Fish & Wildlife Service’s Endangered Species List, once occupied grasslands and tallgrass prairies of the Northeast and Upper Midwest, but most of these habitats have been lost or degraded.

— U.S. Fish and Wildlife Service

From ecoRI News (ecori.org)

Most of the many news reports about the decline of bees and other pollinators focus on only one side of the story: the drop in honeybee numbers because of colony collapse disorder and its impact on food crops. Yet, as important as that issue is to human food security, it only affects one pollinator species, the European honeybee, a non-native species that is managed by commercial beekeepers.

The decline of native pollinators, of which there are thousands of species in North America that affect thousands of additional species of plants and animals, is largely ignored. Robert Gegear is trying to change that.

The assistant professor of biology at the University of Massachusetts at Dartmouth has launched a citizen science program called the Beecology Project to learn more about the ecology of native pollinators, starting with bumblebees, to better understand why some species are doing so poorly while others remain common.

“The survival of native pollinators has a positive cascading effect on so many other species, both the wild plants they pollinate and the other wildlife using those plants for food, shelter, and nest sites,” Gegear said. “Collectively, those relationships are increasing ecosystem health. But as we start to remove pollinators, we start to affect all these other species.

“Certain pollinators are heading toward extinction, but an equal or greater number have not been affected and are increasing. In ecology, it’s about diversity — not how many individuals you see but how many species you see, since each species has a connection with a flowering plant that has a connection to other species.”

For example, Gegear noted that Bombus impatiens, the common eastern bumblebee, is abundant, expanding, and easy to attract to flower gardens, but many other bumblebee species that used to be common are declining rapidly. Why that is happening is unknown.

“It could be that whatever we’re doing to the environment to drive declines in many species of bumblebees is having a direct positive impact on Bombus impatiens,” he said. “We use a lot of non-native plants in our gardens, and Bombus impatiens loves non-native plants, but other bumblebees don’t like non-natives. That’s one possibility. Or impatiens could be more flexible in its use of nest site habitat. We may be removing habitat that supports species that are less flexible in their nesting requirements. We have evidence for both explanations.”

Among the species formerly common in southern New England and are now quite rare are the yellow-banded bumblebee, the yellow bumblebee, the half-black bumblebee and the rusty patched bumblebee. The U.S. Fish & Wildlife Service recently added the rusty patched bumblebee to the Endangered Species List.

The populations of some of these rare species declined especially fast. When Gegear was conducting his doctoral research in the late 1990s, the yellow-banded bumblebee was so abundant that he considered it a pest. Five years later, however, and he couldn’t find it for miles around his research sites.

“The problem is that we don’t know enough about the natural history of most of these species,” he said. “We know virtually nothing about their nesting preferences, about their overwintering preferences, their floral preferences. They have those preferences for a reason, but if you look at plant lists for bumblebees, everything is equal for all species, and that’s not the case.”

Since little is known about which flowers the rare species prefer, many of the growing number of pollinator gardens being installed around the region aren’t benefitting the species most in need. Instead, they’re just helping the species that are already common.

“People want to help, and they have good intentions, but the science isn’t there to tell them what they should be planting,” Gegear said. “I’m trying to fill in those gaps and change the focus of pollinator research by taking more of an ecological approach.”

To do so, he needs large amounts of data. To collect that data, he has turned to the general public. He teamed with computer scientists at Worcester Polytechnic Institute to develop a web-based app to enable anyone to take photos and videos of bumblebees they see, identify them to species, identify the flowers they are visiting, and submit to Gegear’s database.

Based on the data he has already received, new populations of the rare bumblebee species have been found that will enable him to establish new research sites to learn more about those species. Many participants in the program are even planting gardens with the flowers those rare species prefer to boost those bumblebee populations.

Female monarch butterfly.

From ecoRI News

It’s not just bumblebee preferences that are little known. The same is true of the floral preferences of other pollinators. Gegear plans to expand his app to include observations of butterflies and other types of bees. Eventually, he hopes to expand it further so it can be used to conserve pollinators across the country.

“I put a plant on my property last year that we learned one species prefers, and as soon as it came into bloom, the threatened species came in,” he said. “So this approach really does work.”

Gegear is seeking to recruit more Beecology Project volunteers from throughout the region.

“And if you don’t want to use the app, just take a 10-second video of any bumblebee you see and send it to me,” he said. “That’s just as good.”

Rhode Island resident and author Todd McLeish runs a wildlife blog.