Wednesday, June 22, 2016

The Dance of Yellowstone's Wildflowers and Pollinators

When I lived for three winters in Yellowstone’s snowy Lamar Valley, I focused on learning about the big influencers: wolves and coyotes, bison and elk. I began to understand, for example, the intricate dance of wolves and elk and cottonwoods. Now that I live near Yellowstone year around, I have the time and luxury to learn about tiny things. In June that means wildflowers and their pollinators. 

While pollinators may be small, they are essential. So essential that nine years ago the U.S. Senate unanimously approved designating a week in June as “National Pollinator Week.” This year that week is June 20 to 26.
   
Bee in prickly pear blossom (Rick Lamplugh)
Whether I’m hiking down into Hellroaring Valley or up Bunsen Peak, driving the Grand Loop toward Dunraven Pass, or bicycling dirt roads north of the park, wildflowers abound, enticing pollinators. And in the soft warmth of my second spring here, I have spent a lot of time on hands and knees enjoying the intricate dance between host and helper. The flowers that I crawl among depend on insects—rather than wind—for pollination. So they must attract their helpers. Color, scent, and shape are a flower's calling card. It turns out that some wildflowers attract only certain pollinators and some pollinators play favorites, too. 

Some insects are more sensitive to colors than we humans are. Those insects use that sensitivity, says Ronald Taylor in Rocky Mountain Wildflowers, to decide where to dine. The most common wildflower colors are white, like Rocky Mountain phlox, and yellow, like arrow-leaf balsomroot, both plants that abound in Yellowstone. Since those two colors can be seen by most pollinators, white and yellow flowers employ what Taylor calls a generalist strategy: they invite a wide variety of pollinators, especially flies and beetles. And they aren’t just open for business during the day; their light colors attract moths at night. 

Some flowers are more particular about who climbs inside; they take a niche approach to pollination. Pink to red flowers—like Yellowstone’s wild geraniums and paintbrush—attract fewer pollinators. While butterflies and hummingbirds come calling, bees are blind to the beauty of red. They do not visit red flowers unless attracted by something other than color, maybe an odor. Instead, bees buzz to blue penstemon or forget-me-nots. Green and brown flowers, says Taylor, usually attract insects such as wasps and beetles with odor rather than color, since most pollinators do not associate green or brown with flowers.

Bee photo public domain
In addition to color, a wildflower’s shape determines who visits. Some pollinators learn to connect specific shapes with the nectar and pollen they seek. Bees, for example, have an unusual ability to distinguish among shapes. They know what they like and stick to it: flowers with enlarged lower petals that act as a landing pad. Color that flower blue, and bees make a beeline for it.

Flowers with petals arranged in a dish shape, such as wild strawberry, make pollination easy for lots of insects, says Taylor. But bumblebees and hummingbirds shun these popular plants because they won’t get enough bang for their buck. Too many other pollinators have beat them to the good stuff.

Bell shaped flowers, such as plumed avens (also called “Old Man’s Whiskers” or “Prairie Smoke”), are usually pollinated by bees or flies that can contort their bodies. Bees can hang upside down inside the flower and vibrate their wings, shaking the pollen onto themselves. 

Other plants—such as sunflowers—have nectar at the base of the petals. This treat, says Taylor, can only be reached by some bees, flies, and butterflies that have a moderately long tongue. Pollinators with an even longer tongue—moths, butterflies, and hummingbirds—can drink from flowers shaped like long tubes.

One day, I watched two types of bees fly into and out of the lovely red, yellow, and peach flowers of prickly pear cacti that grow among the sagebrush along the flank of Sheep Mountain just outside Yellowstone. When I looked into a nearby blossom that I thought was empty, I discovered an ant crawling around inside. I found ants in several other flowers and wondered if they are pollinators.

Ant in prickly pear blossom (Rick Lamplugh)
Taylor didn’t have much to say about these thin-waisted, six-legged wonders, but the U.S. Forest Service did. Ants love nectar because it is filled with much-needed energy.  But crawling to and into each flower uses energy. To balance energy input and output, ants favor low growing, small flowers that are close to the stem, like the flowers of the prickly pear in which I saw them. 

While ants get the food they need, the USFS said that they may not help much with pollination. That surprised me: here were ants crawling into and out of pollen-filled blooms. Why wouldn’t they be pollinators? I decided to take a closer look, and on my computer screen, zoomed in on a photo I had taken of an ant inside a prickly pear blossom. The ant had fewer pollen grains sticking to its legs and body than did the bees that I photographed that day in other nearby blossoms. Even with fewer grains, the ant could still be part of pollination, couldn’t it? I checked online and found that scientists have discovered that pollen grains on the bodies of some ants have been killed by an antibiotic the ants produce to protect themselves from bacterial and fungal infections.

However the dance of pollination is performed, it results in a plant’s seed and fruit production. But a pollinator doesn't know or care that the plant benefits. As PollinatorParadise.com states, "In the economy of nature, the pollinators provide an important service to flowering plants, while the plants pay with food for the pollinators and their offspring.” Pollination is just another of nature’s wonderful and practical symbiotic relationships. 

We humans clearly benefit from that relationship. About 1,000 plants grown for food, beverages, fibers, spices, and medicines must be pollinated in order to produce the goods on which we depend, according to the organization Pollinator Partnership.

Assassin bug killing bee in cactus blossom (Rick Lamplugh)
But trouble is brewing. Worldwide, pollinators suffer from loss of habitat, chemical misuse, invasive plant and animal species, diseases, and parasites. Scientists estimate that the U.S. has lost more than half of its managed honeybee colonies over the past 10 years. 

The demise of pollinators makes Yellowstone’s bees even more important, and the National Park Service has responded accordingly. Yellowstone’s bees, says Ann Rodman, a park scientist, are just as susceptible to pesticides as bees elsewhere. But park bees are lucky to live far from large agricultural areas where pesticides kill. Plus, as of this June, the Park Service has stopped using nationwide the neonicotinoid pesticides that harm bees. As bees decline elsewhere, Yellowstone becomes a biological reserve that helps preserve bees in much the same way that the park preserved bison and wolves. 

As I write this, bees—my favorite pollinator—are no longer buzzing around the large lilac and honeysuckle bushes that bring blessed shade to our high-desert backyard. But the next time that I encounter bees, I’ll get down on my hands and knees to watch them and thank them—even if they don’t care that I benefit from their labor and love watching them work.

To watch a short slideshow with music that captures the beauty of Yellowstone’s cactus bloom, click here.

To learn how you can help pollinators click here.

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