Archives For Ecology & Wildlife

The Chicago Botanic Garden is actively maintaining, restoring, and recreating four natural areas at the Garden: woodlands at McDonald Woods and the Brown Nature Reserve, the Dixon Prairie, the Skokie River Corridor, and the 60-acre Garden Lakes. These activities teach restoration ecologists a great deal about habitat management, which can be applied in other regions.

When it comes to controlling invasive plants, a little faith can’t hurt. This is particularly true for garlic mustard (Alliaria petiolata).

We have been struggling to get this highly invasive biennial plant under control at the Chicago Botanic Garden for more than 20 years. When I first began working on restoration of our 100-acre Mary Mix McDonald Woods, it took weeks of hand-pulling with many volunteers each spring to clear just 10 or 11 acres. After years of not letting the garlic mustard set seed in the McDonald Woods, a few years ago we finally began to see a light at the end of the tunnel (though we’d still end up with mountains of pulled garlic mustard each year). Thanks to the tremendous help of Garden volunteers, garlic mustard growth in the Woods has finally been curtailed, and each year we are now able to remove all flowering garlic mustard in the Woods’ entire 100 acres.

Garden volunteers pose with a pile of removed garlic mustard at an annual "garlic mustard pull" event.

Over nearly two decades, Garden volunteers have played a critical role in helping remove garlic mustard from the McDonald Woods.

About six or seven years ago, we began a new ecological restoration project in the Barbara Brown Nature Reserve (located at the south end of the Garden near Dundee Road). The area was highly degraded and choked with buckthorn shrubs (Rhamnus cathartica). After the buckthorn was removed, the following spring was a nightmare in terms of garlic mustard. Acres upon acres of garlic mustard monoculture required removing several dump truck loads just to begin making a dent in the population.

Garlic mustard takes over after buckthorn is removed from the woods.

After buckthorn was removed from the Barbara Brown Nature Reserve, garlic mustard plants completely dominated the understory vegetation for several years.

Garlic mustard became so dense in the Brown Nature Reserve that we were reluctant to pull it, since the resulting soil disturbance would greatly enhance sprouting of the soil’s dormant garlic mustard seeds. Fortunately, one of the Garden’s creative mechanics devised a basket system on a hand-held scythe. This ingenious tool allows us to harvest the plant tops by cutting and collecting the unripe seedpods—but unlike hand-pulling, using this tool completely eliminates soil disturbance.

Although the Reserve covers only six acres, in the first few years we were not able to remove all the garlic mustard plants before they began to drop their seed. This led to several more years of hand-harvesting to get the population more under control. Fast forward to spring 2017, and we’ve only found about 75 flowering plants to remove so far. What was once viewed as an impossible goal to achieve (i.e., near-total elimination of flowering garlic mustard from the reserve) has actually happened! Too good to be true, perhaps?

A handmade garlic mustard "rake" captures unripe seed heads.

This ingenious device fabricated by one of the Garden’s maintenance mechanics allows us to capture the garlic mustard’s unripe seedheads cut by the scythe’s sharp blade (the curved metal piece along the bottom).

Even with faith as small as a mustard seed, then you can move mountains: nothing will be impossible ― Viola ShipmanThe Charm Bracelet

There have been recent field observations circulating in the Chicago region regarding a possible disease that apparently is having a significant negative effect on garlic mustard (see woodsandprairie.blogspot.com).

Over the past several weeks, observers have reported an almost complete absence of garlic mustard in areas that are undergoing habitat restoration—and this absence has even been observed in areas where no invasive species management has been done. Further, some restoration workers have reported garlic mustard with very “weird” rhizomes that have many small plants emerging along them. This is not at all a normal growth form for garlic mustard. The speculation is that a virus or some other pathogen is deforming and/or killing the plants. This potential pathogen might explain why we have observed such an incredible decline of garlic mustard at the Barbara Brown Nature Reserve this spring.

I have also taken note of several roadside areas along my commute to work that in past years had dense stands of garlic mustard. This spring, I’m not seeing any garlic mustard flowers there at all. Yet quite interestingly, I’m still seeing dense stands this spring in areas outside the Chicago area. What’s going on with our region’s garlic mustard?!

The next few weeks offer a great opportunity for Garden members to check their yards and other nearby areas that in previous years had shown dense stands of flowering garlic mustard. Maybe you’ll see a dramatic decline as well. Since this seems to be a very recent phenomenon, natural resource managers will need to continue monitoring to see if the decline persists.

Wouldn’t it be great if nature offers a way to rid our region of an invasive plant that has been plaguing our natural areas for so long? Stay tuned!


©2017 Chicago Botanic Garden and my.chicagobotanic.org

In recent years, the plight of pollinators has gotten a lot of press, and rightly so.

I spoke with the editorial board of the Chicago Tribune when they were investigating the well-intentioned distribution by General Mills of “one size fits all” wildflower seed packets to combat the declining populations of bees and other pollinators. 

The decline of pollinator populations is well documented around the globe. Much attention has focused on honeybees, which are extremely important agricultural pollinators, but many of our native bees are vastly more imperiled. For example, the rusty patched bumblebee, native to the Upper Midwest, was just listed this month by the U.S. Fish and Wildlife Service as endangered.

A rusty-patched bumblebee on Culver’s root in the UW–Madison Arboretum. Photo by Susan Day, UW-Madison Arboretum.

A rusty-patched bumblebee working on Culver’s root in the University of Wisconsin–Madison arboretum. Photo by Susan Day, UW-Madison Arboretum.

Many people are concerned about these losses and asking what they can do to help support bees, butterflies, and other pollinators. For a start, it’s more beneficial to pollinators to plant species that are native to your region, and perennial. Here are five more pollinator-friendly actions that everyone can take.

  1. Provide resources: For pollinators, this means flowering plants with pollen and/or nectar. Diversity is key, as flowers of different colors and shapes will attract different pollinators. Be sure to provide resources across the entire growing season, so include species that bloom in spring, summer, and fall. Regional native plants are the species our local pollinators evolved with, so they recognize and use them…and you don’t have to worry that they will become invasive!
  2. Provide host plants: The larvae of many butterflies and moths have particular species that they need to eat to develop, as monarchs need milkweed. Providing host plants will ensure that the next generation of butterflies can mature. Just be willing to accept hungry caterpillars eating those plants.
  3. Provide nesting sites: Many insects like to nest in bare ground, hollow stems, or leaf litter. Allowing your yard to be a little less tidy can benefit insects. Many attractive bee houses are available for sale, and do-it-yourself instructions can be found on the web.
  4. Avoid pesticides: Pesticides are designed to kill insects, but sometimes they also kill pollinators unintentionally. Systemic pesticides can persist in plants for long periods of time and are present in all parts of the plant, including nectar and pollen. So if you choose plants for a pollinator garden, make sure they haven’t been treated with systemic pesticides. If possible, make your entire yard pesticide-free.
  5. Learn more about pollinators: There are some great resources on the web—including those created by the Pollinator Partnership and the Xerces Society—that can help you do even more for pollinators.

Help for pollinators begins in your own backyard. These native plants below are recommended to bring back pollinator populations. (Don’t overlook trees—native maples and willows can provide critical resources early in the season.)

Beebalm or bergamot (Monarda fistulosa)

Beebalm, or bergamot (Monarda fistulosa)

New England aster (Symphyotrichum novae-angliae)

New England aster (Symphyotrichum novae-angliae)

Stiff goldenrod (Oligoneuron rigidum)

Stiff goldenrod (Oligoneuron rigidum)

Prairie blazing star (Liatris spicata)

Prairie blazing star (Liatris spicata)

American pussy willow (Salix discolor)

American pussy willow (Salix discolor)

Purple coneflower (Echinacea purpurea)

Purple coneflower (Echinacea purpurea)


Read more about the science behind this important topic in the Natural Areas Journal article, The Importance of Phenological Diversity in Seed Mixes for Pollinator Restoration by Kayri Havens and Pati Vitt, Chicago Botanic Garden.


©2017 Chicago Botanic Garden and my.chicagobotanic.org

What’s black and white and spread all over? Zebra mussels—but they’re no joke.

If you noticed more aquatic “weeds” and algae growing in the Garden Lakes this year—or that our beloved Smith Fountain was MIA after mid-summer—read on to find out why.

Invasive plants and the problems they pose have been the topic of frequent postings here on the Chicago Botanic Garden’s blog. Now we have another invasive species to tell you about—and this time, it’s an animal: zebra mussels.

PHOTO: Adult zebra mussel (Dreissena polymorpha).

Adult zebra mussels (Dreissena polymorpha) are about the size of your thumbnail.

Like many invasive plants and animals, zebra mussels’ native range is a faraway place; in this case, eastern Europe and western Russia. In the past 200 years, they have spread throughout all of Europe and Asia. Here in North America, the first account of an established population was in 1988 in Lake St. Clair (located between Lakes Huron and Erie), likely arriving here as tiny hitchhikers in the ballast water of a single commercial cargo ship traveling from the north shore of the Black Sea.

Somewhat remarkably, over the next two years they had spread throughout the entire Great Lakes. Just a year later in 1991, zebra mussels had escaped the Great Lakes and begun their march across North America’s inland waters. (Watch an animation of their spread). Today they are found in at least 29 states.

A zebra mussel may live up to five years and produce up to one million eggs each year—that’s five million eggs over their lifetime. A freshwater species of mollusk, they prefer to live in lakes and rivers with relatively warm, calcium-rich water (to help support their shell development). They feed by filtering microscopic algae from the surrounding water, with each adult zebra mussel filtering up to one liter of water per day.

Though tiny in size (adults are typically ½ to 2 inches long), their ecological and economic impacts can be enormous. Adult zebra mussels prefer to attach to hard surfaces such as submerged rocks, boat hulls, and pier posts—but they also cling to water intake structures as well as the interior of most any pipe that has flowing water in it (such as drinking water supply and irrigation system piping). From an ecological perspective, zebra mussels’ removal of microscopic algae often causes the afflicted waterway to become much more “clear.” While this clearer water may otherwise seem like a good thing, the now-removed microscopic algae is an important food source for many native aquatic animals. The clearer water also allows sunlight to penetrate deeper into the water, thereby stimulating much more rooted aquatic plant growth.

Nearby, zebra mussels were first identified in 2000 at the Skokie Lagoons, just south of the Garden. In 2013 and again in 2014, just a few zebra mussel shells were found at the Garden on the intake screens for our irrigation system’s South Pumphouse. Since so few mussels were found, we were hoping that the Garden’s lakes were simply not a hospitable place for the zebra mussels to flourish. Unfortunately, that thinking all changed in 2015….

PHOTO: Waterfall Garden label covered in zebra mussels.

These zebra mussels, only a few months old at the time, completely covered this plant label that had inadvertently fallen to the bottom of the Waterfall Garden’s upper pool.

At our Waterfall Garden, 1,000 gallons per minute of lake water are pumped to the top of the garden, after which the water flows down through the garden’s channels and then back into the lake. When Garden staff drained the Waterfall Garden for cleaning in June 2015, there were no apparent zebra mussels present—but by September 2015, the entire bottom of the Waterfall Garden’s upper pool was completely encrusted with attached zebra mussels. Needless to say, we were more than a little alarmed.

Realizing that the Garden’s lakes could indeed support massive growth of zebra mussels, the Garden’s science, horticulture, and maintenance staff quickly came together to devise a remediation strategy that would protect two critical components of the Garden’s infrastructure from “clogging” by zebra mussels: our irrigation system (which utilizes lake water to irrigate nearly all of our outdoor plant collections) and our building cooling systems (three of our public buildings extract lake water to support their air conditioning systems).

PHOTO: One of the Garden's lake water filtration systems.

Automatic backwash filters like the ones pictured here will be added to each of the Garden’s three pumping stations that withdraw lake water to irrigate nearly all of our outdoor plant collections.

The Garden’s zebra mussel remediation team drew upon the best scientific expertise available in North America, which confirmed that there is no scientifically proven approach for removing all zebra mussels from a body of water. The team explored all potential options for eliminating zebra mussel impacts on our infrastructure, and ultimately settled on two approaches: first, the installation of automatic backwash filters to keep even the tiniest of zebra mussels from getting into our irrigation system (the youngest zebra mussels are about 70 microns in size, or about the width of a human hair), and second, the installation of conventional closed-loop “cooling towers” on the three Garden buildings that currently use lake water for air conditioning (thereby discontinuing all withdrawals of the lake water for building cooling). Final design of the backwash filtration systems and the cooling towers is currently underway, and our intent is to have everything installed and operational by spring 2017.

PHOTO: The Garden’s aquatic plant harvester cuts and removes excessive aquatic vegetation and algae from the Garden lakes.

The Garden’s aquatic plant harvester cuts and removes excessive aquatic vegetation and algae from the Garden lakes.

If you visited the Garden in 2016, you probably witnessed some of the zebra mussels’ ecological impacts to our lakes. Mid-summer lake water transparency in our lakes typically is about 3 to 4 feet—but in 2016, this increased dramatically to about 6 feet (likely due to the zebra mussels’ filtering abilities described earlier). This clearer water resulted in much great submerged aquatic plant growth in our lakes, and our aquatic plant harvester struggled to keep up. Many visitors commented that there was much more aquatic “weed” growth in the lakes this year—and they were correct.

In fact, there was so much aquatic plant growth in our lakes this summer that the water intake for Smith Fountain in the North Lake became clogged and the pump burned out. Look for a repaired Smith Fountain (with a more clog-resistant intake) to reappear next spring.

PHOTO: The Smith Fountain (which is illuminated at night) is an acclaimed feature in the North Lake.

The Smith Fountain (which is illuminated at night) is an acclaimed feature in the North Lake.

While there currently is no known way to eliminate zebra mussels from freshwater lakes and streams, Garden researchers intend to utilize the new aquatic research facilities in the emerging Kris Jarantoski Campus to explore experimental approaches, such as biological control agents, to potentially lessen the zebra mussels’ ecological impacts to our 60-acre system of lakes. Stay tuned.


©2016 Chicago Botanic Garden and my.chicagobotanic.org

With more than 1,850 known species of moths in the state of Illinois—more than ten times the diversity of butterflies—it is a real adventure sampling the moth species inhabiting the McDonald Woods at the Chicago Botanic Garden.

Using a combination of light and bait traps along with visual searches, I have been investigating the diversity of moth species found in the restored portions of our oak woodland. Moths are removed from the traps and then photographed before being released back to the woodland.

PHOTO: Ctenucha virginica (Virginia Ctenucha) moth.

The metallic scales of Ctenucha virginica (Virginia Ctenucha moth) are striking—even its wings have a metallic sheen.

My interest in moths stems from the fact that many of the species are dependent on one or just a few native plant species for their survival, and as a result, may serve as valuable indicators of the health of our recovering, once-degraded oak woodland. The larval stages—the caterpillars—primarily feed on the roots, stems, and leaves of the plants. Adult moth species are very important pollinators. White-flowered and night-fragrant plant species are often what they seek. There are day-flying moths also, like some of the hawk moths (which are often mistaken for hummingbirds) that are seen visiting a variety of flowers in full daylight. Moths are also a tremendously important part of the food chain. Entomologist Doug Tallamy tabulated the number of caterpillars that were utilized to support one nest of black-capped chickadees and found that they consumed between 6,000 and 9,000 caterpillars, most of which were moth species. Adding even a few native plant species to your yard can benefit a multitude of these valuable invertebrates.

PHOTO: Smerinthus jamaicensis (Twin-spotted sphinx moth).

Smerinthus jamaicensis (Twin-spotted sphinx moth)

PHOTO: Plusia contexta (Connected looper moth).

Plusia contexta (Connected looper moth)

PHOTO: Ponometia erastrioides (Small bird-dropping moth).

Ponometia erastrioides (Small bird-dropping moth)

PHOTO: Plagodis phlogosaria (Straight-lined Plagodis moth).

Plagodis phlogosaria (Straight-lined Plagodis moth)

It is a never-ending surprise to see what new species will show up each time traps are placed.

Some species are so small (usually referred to by lepidopterists as micromoths) that most people would pass them off as gnats or pesky flies. Some micromoths are only 3-4 millimeters long. One in particular I like to refer to as the “Nemo” moth, as in Finding Nemo. I gave this species that name because its colorful pattern reminds me of a clown fish.

PHOTO: A cryptically-colored Noctua pronuba (Large yellow underwing moth).

A cryptically colored Noctua pronuba (Large yellow underwing moth)

At the other end of the spectrum are the moth species that are quite large. The giant silkworm moths, like the luna and Cecropia moths, have a wingspan of more than 140 millimeters. Starting in mid-July and going through September, a group of medium to large moths known as underwing moths starts appearing in the woods. These delta-shaped species are usually very cryptically colored on their forewing and brightly and starkly colored on their hind wing. The cryptic forewing allows them to blend in with the tree trunks they are resting on; the hindwing only becomes visible when they spread their wings to fly. It is thought to be a distraction or scare tactic to foil predators.

Although there is a subtle nuance of shapes, colors, and textures that distinguish many species, there are also those that are in-your-face with shockingly bright colors, metallic ornamentation, stark patterns, and jagged ridges of scales—much like a mountain range on six legs—that never fail to impress me. The looper moths are one good example. Many have stigmas (distinctive white patches and scrolling) on the surface of the wing and spectacular assortments of peaks, crowns, and ridges of scales on the thorax and inner edges of the wings. The scale patterns most likely evolved to break up the silhouette of the moth to make it less visible. One of the hooded owlet moths has a tall patch of scales on its thorax that looks like a witches hat when erect, but it can also be laid down over the moths head to make it look like a broken-off stick.

PHOTO: Leucania pseudargyria (False wainscot moth).

Leucania pseudargyria (False wainscot moth)

In general, there is a new group of species that emerges about every two weeks during the year, with midsummer being the peak for species and abundance. Many moth species have relatively short flight periods and can only be seen at certain times of the year, but some have multiple broods that show up several times during the year. When I show some of these moths to colleagues, they almost always say, “I never knew these things existed.”

Under the cover of darkness, there is a world of beauty and fascination fluttering silently among the trees. It makes me wonder if the full moon doesn’t show up once a month just to shed a little light on the show, just so we don’t miss it completely.


©2016 Chicago Botanic Garden and my.chicagobotanic.org

It’s time for a visit to the Dixon Prairie to savor late spring flowers and the pollinators visiting these plants.

White wild indigo (Baptisia alba var. macrophylla)

White wild indigo (Baptisia alba var. macrophylla)

A standout plant, looking almost like a small shrub, is white wild indigo (Baptisia alba). This is the white-flowered cousin to blue wild indigo (Baptisia australis); this plant, not native to the Chicago region, was historically a source for blue dye. Both species are in the pea family. Many prairie plants belong to the pea family; other important families of the prairie are sunflower, sedge, and grass. Queen and worker bumblebees primarily pollinate white wild indigo. Their large size allows them to push down the lower part of the flower (the keel) and thus expose the pollen producing anthers. 

A rich palette of blue flowering plants from the Ohio spiderwort (Tradescantia ohiensis) surrounds the white wild indigo plants. A variety of bees and butterflies might be seen visiting these plants, bumblebees being the primary pollinator. Butterflies, in their quest for nectar, will not be rewarded for their visit, however, since Ohio spiderwort doesn’t have nectar.

Spiderwort (Tradescantia 'Sweet Kate') and coneflowers bloom on the Prairie.

Spiderwort (Tradescantia ‘Sweet Kate’) and coneflowers bloom on the prairie.

The prairie also currently hosts numbers of white tubular flowers, foxglove beardtongue (Penstemon digitalis). On the lower half of the flower is a large hairy sterile stamen (the part of the flower that produces pollen); perhaps this feature is the origin of the plant’s common name. Pollinators, primarily bees, must work their way past this sterile stamen to reach pollen. This effort increases the likelihood of pollen being deposited on the stigma, the organ that is receptive to pollen. Those willing to observe these flowers for a while might be rewarded with witnessing some territory defending. The male of an introduced bee, the European wool carder bee, with sharp spines on their abdomens, will attack other males who come in the vicinity of the female when she is foraging for nectar. 

Pale coneflower (Echinacea pallida)

Pale coneflower (Echinacea pallida)

Just opening on the gravel hill prairie is the pale coneflower (Echinacea pallida). The narrower leaves of this plant distinguish it from the commonly planted purple coneflower (Echinacea purpurea) (sometimes called broad-leaved coneflower). Like other members of the sunflower or aster family, the coneflower has what appears to be a singular flower but is actually a head of many flowers. This species has what are called ray and disc flowers. Some sunflower plants have only disc flowers while others, such as dandelions, only ray flowers. This plant is a preferred nectar plant of both bees and butterflies. 

Moving into summer, this palette will change and reveal a new tapestry of grasses and wildflowers. To witness the full bounty of the prairie, a prairie visit should be a weekly affair.


©2016 Chicago Botanic Garden and my.chicagobotanic.org