[Pollinator] The Buzz on Native Pollinators

[Scott Black]

http://www.nwf.org/nationalwildlife/article.cfm?issueID=129&articleID=1735

NATIONAL WILDLIFE MAGAZINE
June/July 2009, vol. 47 no. 4

The Buzz on Native Pollinators
By Laura Tangley

As European honeybees decline, indigenous bees 
and other pollinating animals can provide a 
backup­with a little help from their human friend

WHEN ECOLOGIST Rachel Winfree set out to survey 
native bees in the Delaware Valley of New Jersey 
and Pennsylvania, she was not optimistic about 
her results. Not only is the region far from any 
known hot spots of bee diversity, such as the 
U.S. Southwest, “New Jersey is also the most 
densely populated state in the country,” says 
Winfree, an assistant professor in the Department 
of Entomology at Rutgers University. “I was 
worried that after getting funding and hiring a 
staff, the project would turn out to be a waste of time.”

Her fears were unfounded. “We found bees 
everywhere,” says Winfree­thousands of 
individuals of 46 different species. More 
surprising, she and her colleagues discovered 
that the number of flower visits by these natives 
was sufficient to fully pollinate the watermelon 
crop on 21 of 23 farms in her study region.

Gleaning such data was the goal of Winfree’s 
work. As European honeybees decline in a 
mysterious phenomenon known as Colony Collapse 
Disorder (CCD), “I wanted to find out whether 
native bees could fill in for them,” she says. 
While Winfree cautions against extrapolating her 
results too broadly to other crops in other parts 
of the country, “if we lost all honeybees in this 
region to CCD tomorrow, between 88 and 90 percent 
of the watermelon crop would be fine,” she says. 
“Native bees are providing a backup plan­for free.”

Winfree’s results, published in Ecology Letters, 
have generated an excited buzz among native 
pollinator proponents, a diverse group of 
scientists, conservationists, gardening 
enthusiasts and others who are sponsoring 
activities nationwide this June to celebrate the 
third official National Pollinator Week. Yet even 
as they applaud her study­and others that show 
wild bees contribute to the production of crops 
such as blueberries, cranberries, peppers, 
tomatoes, alfalfa and squash­they worry about the 
welfare of these unsung natives.

[]


“There has been little effort to document the 
long-term status of pollinator populations in the 
United States,” says biologist May Berenbaum, 
chairman of the Department of Entomology at the 
University of Illinois at Urbana-Champaign. Yet 
in a 2006 National Academy of Sciences (NAS) 
report, a scientific committee chaired by 
Berenbaum found that in cases where data do 
exist, pollinator population trends are “demonstrably downward.”

Pollinators comprise a diversity of wild 
creatures, from birds and bats to butterflies, 
moths, beetles, flies and even the odd land 
mammal or reptile. But “there’s no question that 
bees are the most important in most ecosystems,” 
says Winfree, who calls the insects “the 
800-pound gorillas” of the pollinator world. 
Unlike social honeybees, imported to North 
America in the 1600s, the majority of the 
continent’s native bees are solitary, nesting in 
burrows on the ground or small holes in wood 
rather than building hives. Worldwide, there are 
some 20,000 bee species, 4,000 of them found in North America.

Bees and other pollinators are essential to human 
survival. “Without them, you’d lose most of your 
plants, and ultimately everything else,” says 
Winfree. To produce seeds and reproduce, 
three-quarters of the world’s flowering plant 
species rely on animal pollinators. (The others 
use the less precise methods of wind or water to 
transfer pollen between male and female flower 
parts.) Animal-dependent plants include more than 
two-thirds of the world’s crop species, whose 
fruits and seeds provide more than 30 percent of 
the foods and beverages we consume. Scientists 
estimate that in the United States alone, native 
bees perform up to $3 billion worth of pollination services annually.
[]


Natural ecosystems and their inhabitants also 
rely on pollinators. Many North American 
songbirds, for instance, feed on the fruits, 
seeds and berries of plants pollinated by 
animals. Pollinating insects themselves, 
especially their plump larvae, provide protein 
for adult songbirds and their fast-growing 
fledglings. Even the notoriously carnivorous 
grizzly bear depends more directly on pollinators 
than one might expect. According to wildlife 
ecologist Kimberly Winter, NWF’s habitat programs 
manager, in some places between 80 and 90 percent 
of the bear’s diet is made up of fruits, nuts, 
bulbs and roots of animal-pollinated plants. On 
an ecosystem level, “losing a pollinator can have 
a domino effect on countless other species,” she says.

To detect pollinator population trends, long-term 
surveys are essential. “The few hardy souls who 
have undertaken such studies are finding 
indisputable evidence of declines,” says 
Berenbaum. She cites the work of biologist Arthur 
Shapiro, a professor of evolution and ecology at 
the University of California–Davis who has been 
monitoring butterflies on fixed transects across 
the state for the past 37 years. Many of the 
several dozen species he has tracked have 
declined, some dramatically. “Butterflies that 
were once considered utterly common are going 
into a tailspin, and no one knows why,” says Shapiro.

In addition to butterflies, the NAS report 
provides evidence of decline in three other 
pollinator groups: hummingbirds, bats 
and­especially­bumblebees. A 2008 report from the 
Xerces Society for Invertebrate Conservation, a 
nonprofit based in Portland, Oregon, paints an 
even bleaker picture of the familiar, fuzzy 
insects’ fate. Compiling data from more than 
three dozen scientists and “citizen monitors” 
across the country, the report concludes that 
populations of three formerly common species­the 
rusty-patched, yellowbanded and western 
bumblebee­have dropped drastically over the past 
decade. A fourth species, Franklin’s bumblebee 
(restricted to coastal Oregon and Northern 
California), has only been seen once in the past several years.

Though the jury is still out on the cause of 
these declines, the most likely culprit is an 
exotic disease introduced by commercially reared 
bumblebees, says the society’s executive 
director, Scott Hoffman Black. Between 1992 and 
1994, he explains, queens of the western 
bumblebee, a species commonly used to pollinate 
greenhouse tomatoes, were shipped to Europe to 
produce colonies subsequently shipped back to 
U.S. farms. Scientists suspect the bees picked up 
a fungal disease from European bees, then spread 
it to wild bumblebees across the country as 
colonies were moved among commercial growers. 
(All beleaguered species are closely related to 
those that spent time in Europe.) “Like Native 
Americans decimated by smallpox brought in by 
Europeans, our native bees have no resistance to 
exotic diseases,” says Hoffman Black.

Beyond disease­suspected as a major cause of CCD 
in honeybees­blame for pollinator declines runs 
the gamut: habitat loss and fragmentation, 
introduced species, pesticides and global 
warming. “But in most cases, we don’t know,” says 
Laurie Davies Adams, executive director of the 
Pollinator Partnership, a San Francisco-based 
nonprofit working to raise awareness about 
pollinators’ plight. “We simply haven’t paid enough attention.”

There are a handful of exceptions. In the U.S. 
Southwest, two species of nectar-feeding bats­the 
lesser long-nosed and Mexican long-tongued 
bat­have declined due to destruction of their 
roosting caves. Pesticides are implicated in 
problems facing several native insects, though 
given the animals’ special sensitivity to these 
chemicals, “pathetically few toxicity studies 
have been conducted, even on honeybees,” says Berenbaum.

[]


Like virtually all living things, pollinators are 
also threatened by global warming. According to 
biologist David Inouye of the University of 
Maryland, some are already beginning to respond 
to climate change. In the Colorado Rockies, for 
example, he and his colleagues recently surveyed 
the altitudinal distribution of several bumblebee 
species at the Rocky Mountain Biological 
Laboratory (RMBL). They compared the results with 
those of a survey they had conducted along the 
same transects as graduate students more than 30 
years ago­and found that at least one species has 
shifted its range upslope by 1,500 feet.

Pollinators are particularly at risk to indirect 
effects of warming­when changes in temperature or 
precipitation cause shifts in the distribution of 
plants or the timing of nectar they produce. In 
another study at the Colorado lab, Inouye and 
RMBL colleague Billy Barr found that springtime 
emergence of Milbert’s tortoiseshell butterfly 
has been getting progressively earlier since the 
1970s. Yet blooming time of the region’s spring 
wildflowers has not kept up. The findings 
demonstrate that “pollinators and plants do not 
respond the same way to environmental changes 
caused by global warming,” says Inouye. “This 
means they may lose the synchrony they once had.” 
Inouye is particularly concerned about 
hummingbirds­important wildflower 
pollinators­that migrate thousands of miles 
between winter habitats in the Tropics and 
breeding grounds in North America. Research shows 
that tropical and temperate ecosystems are 
responding very differently to global warming, 
and there’s no way a hummingbird wintering in 
Colombia would be able predict what the weather is like in Colorado.

[]


Fortunately, there’s good news as well. Thanks to 
the NAS report and efforts of conservationists, 
there has been a flowering of appreciation for 
native pollinators in recent years. Concern about 
European honeybees has also helped. CCD, first 
detected soon after the report’s publication, had 
“a silver lining,” says Hoffman Black. “Now many 
more people know that their food is pollinated, 
and that we need bees and other animals to do that.”

Davies Adams agrees that “we see more interest in 
pollinators than just a few years ago­and more 
resources to help people help pollinators.” Among 
her organization’s activities is the creation of 
a series of ecoregional planting guides to advise 
gardeners on planting native species for insects 
and other animals. Launched in 2008, the final 
set of 32 guides is scheduled to be completed 
this June. The Xerces Society has published the 
Pollinator Conservation Handbook as well as a 
series of guides for farmers and managers of 
parks, golf courses and other lands.

Perhaps the biggest coup scored by pollinator 
proponents came last year with congressional 
reauthorization of the Farm Bill, which for the 
first time has provided specific financial 
incentives to growers who restore habitat for 
pollinators and authorized $100 million for 
research on the animals. Winfree has applied for 
funding through the law to continue working with 
USDA’s Natural Resources Conservation Service in 
New Jersey on combinations of plants that attract 
the greatest diversity of pollinators. She 
suspects the reason she found so many bees in her 
own study is because the region’s small farms are 
nestled among suburban gardens and scraps of 
native vegetation, habitats that provide nesting 
sites and additional food for the insects. 
Similar research conducted within vast 
monocultures of California’s Central Valley has so far been less encouraging.

Winfree, who launched her project in 2006, 
obtained equally promising results during the 
2007 and 2008 growing seasons. “When it comes to 
human disturbances like fragmentation,” she says, 
“some bees may turn out to be more robust than 
some larger animals like birds and mammals. And 
that would be very good news for conservation.”

Senior Editor Laura Tangley provides food, water 
and nesting sites for pollinators in her own yard.
arden for Wildlife

How to Plant for Pollinators

“The neat thing about pollinator conservation is 
that anyone, from the owner of a golf course to 
an apartment dweller with a window box, can do 
something to help,” says Scott Hoffman Black, 
executive director of the Xerces Society for 
Invertebrate Conservation. All it takes is to 
provide appropriate food and habitat for bees, 
butterflies and other pollinating species­and to 
avoid using the pesticides that harm them.

“Being pollinator-friendly also means you are 
being wildlife-friendly,” says Kimberly Winter, 
NWF’s habitats program manager. “And you are 
creating a sustainable ecosystem in your own backyard.”

Here are a few suggestions to get started:

To provide pollinators with the best sources of 
food­and to prevent the spread of invasive 
species­choose as many plants native to your 
region as possible. For specific recommendations, 
consult the Pollinator Partnership’s free 
ecoregional planting guide for your area 
(<http://www.pollinator.org>www.pollinator.org); all you need is a zip code.

Select plants that provide a lot of nectar and 
pollen. Many ornamentals have been specifically 
bred to produce little or none of these essential foods.

Plant a diversity of species so your yard will 
provide bees, butterflies and other animals with 
nectar and pollen from spring through fall. To 
attract bats and nocturnal moths, consider 
night-blooming plants in addition to day-bloomers.

Be a “messy” gardener: Leave some patches of 
unmulched soil and brush piles that bees, birds 
and other animals can use to construct nests. 
Consider building or purchasing a bee house for wood-nesting wasps and bees.

During hot, dry periods, provide water in shallow 
birdbaths or pools where pollinators can easily 
alight. Some wasps and bees need mud to build 
their nests, and butterflies like to gather in muddy puddles.

Do not use pesticides, and encourage your 
neighbors to reduce their reliance on these 
chemicals. According to Winter, more pesticides 
are used in urban areas today than in 
agricultural regions of the United States.

For more tips, check out these sites: 
<http://www.nwf.org/nationalwildlife//gardenforwildlife>www.nwf.org 
and <http://www.xerces.org>www.xerces.org.
riority

Protecting Native Pollinators

Through its Certified Wildlife Habitat™ program, 
NWF encourages the creation of habitat suitable 
for bees, birds, butterflies and other 
pollinators, and educates landowners about 
appropriate host plants as well as the risks of 
using pesticides. The program also offers all the 
information needed to make your own yard 
welcoming to pollinators and other native 
animals. Once you create this haven, you can have 
the property certified as an official NWF 
wildlife habitat. To learn more, go to 
<http://www.nwf.org/nationalwildlife//gardenforwildlife>www.nwf.org/gardenforwildlife.
b Exclusive

Photo Challenge: Plants and Pollinators

[]
To celebrate National Pollinator Week (June 
22–28), National Wildlife is hosting a “Plants 
and Pollinators” photo challenge competition on 
Flickr. We’re looking for images of bees, 
butterflies, hummingbirds and other animal 
pollinators, as well as the plants that depend on 
them for survival. If you’ve got photos fitting 
this description, upload them to the 
<http://www.flickr.com/groups/nwmag?&s_src=Flickr_Photo_Challenge&s_subsrc=June_July_2009_NW_online>National 
Wildlife<http://www.flickr.com/groups/nwmag?&s_src=Flickr_Photo_Challenge&s_subsrc=June_July_2009_NW_online> 
Magazine Photo Group by June 28 (with the tag 
"Pollinator-NW09") for your chance to win. In 
July, we will select finalists among these images 
and ask Flickr members and others to vote for 
their favorite. The top vote-getter will receive 
an official NWF wildlife field guide and, if not 
already a member, a one-year membership to the 
National Wildlife Federation. This membership 
includes a free subscription to National Wildlife magazine.

For more details about the photo challenge, visit 
the 
<http://www.flickr.com/groups/nwmag?&s_src=Flickr_Photo_Challenge&s_subsrc=June_July_2009_NW_online>National 
Wildlife<http://www.flickr.com/groups/nwmag?&s_src=Flickr_Photo_Challenge&s_subsrc=June_July_2009_NW_online> 
Magazine Photo Group page on Flickr.

Please help us to protect our natural resources, 
reuse or recycle this paper when you are done.

© 2009 National Wildlife Federation, All rights 
reserved. - Read more great stories online at www.nwf.org/nationalwildlife



*************************
Scott Hoffman Black
Ecologist/Entomologist
Executive Director
The Xerces Society for Invertebrate Conservation
4828 SE Hawthorne
Portland, OR 97215
Direct line (503) 449-3792
sblack at xerces.org

The Xerces Society is an international, nonprofit 
organization that protects wildlife through the 
conservation of invertebrates and their habitat.

To join the Society, make a contribution, or read about our work,
please visit <http://www.xerces.org/>www.xerces.org.


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