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.

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

Want to help monarch butterflies? Be careful when selecting your milkweed. Not all plants that go by the common name of “milkweed” are the food that these butterflies need. 

Want to save the monarch butterfly? Plant milkweed. Pick up a free milkweed seedling at World Environment Day this Saturday, June 4.

Danaus plexippus (Monarch) egg on the underside of a leaf.

Danaus plexippus (Monarch) egg on the underside of a leaf. Photo by Bfpage [CC BY-SA 4.0], via Wikimedia Commons

Milkweed is both a food source and a host plant on which the monarch butterflies lay their eggs. Monarchs lay their eggs on the underside of the milkweed foliage.

After hatching, the larvae consume the foliage, which is high in cardiac glycosides—a poison that interferes with the heart functioning of vertebrates (animals with a skeleton). Butterflies are insects with an exoskeleton, and so are not affected by the toxin.

Within the Chicago region, the following milkweed species (Asclepias) are native:

  • Asclepias amplexicaulis is native to our prairies and is suitable for planting in sunny perennial flower gardens. The flowers are described as “eraser pink” in color and are fragrant (honey).
  • Asclepias exaltata is native to our woodlands and is suitable for planting in partially shaded gardens. The flowers are white and also fragrant.
  • Asclepias incarnata is native to both prairie and woodlands and can be planted in a variety of garden locations. The flowers are pink and fragrant. Gardeners may also be interested in three cultivars of this species:
    • ‘Cinderella’ has light and medium pink flowers
    • ‘Ice Ballet’ has white flowers
    • ‘Soulmate’ has medium and dark pink flowers
  • Asclepias tuberosa goes by the common name of Butterfly Weed. It features bright gold and orange flowers—and is fragrant. A native of sunny prairies, it also has cultivars that have been selected for specific colors:
    • ‘Hello Yellow’
    • ‘Western Gold Mix’
    • ‘Gay Butterflies’ (orange, red, yellow)
  • Asclepias purpurascens has fragrant pinkish-purple flowers and can tolerate both sun and shade locations in the home landscape.

Cultivars may be easier to find in your local garden center or nursery, but specialist nurseries do carry both potted plants as well as seeds.

Asclepias syriaca

Asclepias syriaca

Asclepias tuberosa

Asclepias tuberosa

Download the Chicago Botanic Garden Milkweed Map and take a tour of our native milkweeds.

The Bad Seeds

The bad actors, unfortunately, also go by the common name of milkweed, and are in the same plant family but a different genus: Cynanchum. Three species are reported in the upper Midwest and should not be planted by gardeners. All have fragrant flowers and wind-dispersed seeds:

  • Cynanchum louiseae goes by the name of Louise’s swallow wort, or milkweed. It is native to southeastern Europe.
  • Cynanchum louiseae goes by the name of European swallow wort or milkweed. It is native to southern Europe.
  • Cynanchum vincetoxicum goes by the name of white swallow wort or milkweed. It is native to Europe and Asia.

So, why will monarch larvae die on the wrong milkweed? 

Hmmm, perhaps an illustration. Both mango and poison ivy are in the same plant family (Anacardiaceae) and contain similar biologically active compounds. My daughter and I can’t get enough mango in our diet, but both break out in poison ivy rashes if we touch poison ivy plants. The compounds are similar but not exactly the same.

Likewise with the “bad” and “good” milkweeds: Both have fragrant flowers, the flower shapes are similar, the leaf shapes are similar, both have milky sap. But there is an insecticide compound in the “bad” milkweed in addition to the cardiac glycoside.

“Bad” milkweeds evolved in Europe, where there are no native monarch butterflies, but plenty of herbivores, both animal and insect. “Good” milkweeds evolved in North America in conjunction with monarch butterflies.

Monarch caterpillar

Monarch caterpillar

Somehow, the monarch larvae are able to ingest and retain cardiac glycosides in their tissues without dying. It is a very unique adaptation between these two species. If other species of butterflies were to lay their eggs on milkweed, the larvae would not survive. Each organism has these sorts of “monarch-like” relationships with other, sometimes drastically different organisms that give them a survival advantage. Monarchs just happen to be a wonderful example of mutualistic relationships.

Learn more:

The Monarch Joint Venture lists a number of national and regional partners; each of them will have information about monarch butterflies. The U.S. Fish and Wildlife Service, which is partnering with the National Wildlife Federation and National Fish and Wildlife Foundation, is also a source for information on milkweed and monarchs. Get free milkweed plants at monarchwatch.org.

Million Pollinator Garden Challenge

Add your garden to the Million Pollinator Gardens project this summer. Learn more at millionpollinatorgardens.org.


©2016 Chicago Botanic Garden and my.chicagobotanic.org

While working out in the woods this winter, a small lump on the branch of a young elm tree caught my attention. At first I thought it might be a gall, or an injury that had healed-over. On closer inspection, the lump turned out to be a ruby-throated hummingbird nest from last summer. 

Although I see hummingbirds regularly at the Chicago Botanic Garden, I rarely encounter one of their nests. Hummingbirds themselves are amazing, but their nests are truly a marvel of avian architecture. Not much larger in diameter than a quarter, they are just large enough to hold the one to three navy bean-sized eggs of the hummer. For the pint-sized bird to be able to keep the tiny eggs warm during incubation requires that the nest be not much larger than her body. 

PHOTO: Hummingbird nest and quarter (for scale).

Not much larger than a quarter, the ruby-throated hummingbird nest is an engineering marvel.

This is all well and good until the eggs hatch. Growing young hummingbirds can double or triple the amount of room necessary to hold the family. One of the ways the hummingbirds get around this need for flexibility is that they construct the nest of soft plant fibers and then wrap the whole thing with spiderweb silk. This creates an elastic nest that has the ability to expand as the contents of the nest increases. Can you imagine yourself going out and plucking a strand of sticky silk from a spider web with your fingers and then trying to use it to build something out of lightweight fuzzy plant fibers? I imagine you might find yourself wrapped up in a ball like some sort of oversized grotesque moth cocoon. The silk also helps to anchor the nest to the top surface of a horizontal branch.

PHOTO: Spiderweb silk is used by hummingbirds as a nest liner.

Spiderweb silk: the expandable nest liner preferred by hummingbirds.

Keeping the nest just the right size as the need arises helps to keep the growing youngsters warm and secure. In the western states where several species of hummingbirds nest, often at higher elevations, it is not only important to keep the nestlings warm, but also the incubating female, especially at night. Therefore, it is often the case that hummingbirds in these colder situations will locate their nests on a limb with an overhanging branch acting as a sort of roof to help block the nest from the night sky. 

Although this measure helps reduce heat loss, it is often the case that nesting females will go into a state of torpor (reduced physiological activity to lower body temperature) in order to conserve energy on particularly cold nights. This is a principle of physics in which the larger the difference in temperature between objects, the faster the heat flows from the warmer one to the cooler one. Therefore, a hummingbird with a lower body temperature will lose heat more slowly than the one with a warmer body. As I stated earlier, hummingbirds are amazing!

PHOTO: Parmelia sulcata, a common lichen, is used to help disguise the hummingbird's nest.

Parmelia sulcata, a common lichen, is used to help disguise the hummingbird’s nest.

Part of the reason—besides size—I had not noticed the nest earlier is that the birds do a fantastic job of camouflaging it. This also relates to the spiderweb silk. Some or all of the silk used is sticky. Upon completion of nest construction, the birds collect bits of lichen and attach them to the sticky strands on the outside of the nest. Interestingly, the birds seem to always use the same species of lichen, one that goes by the name of Parmelia sulcata

Parmelia sulcata is a light greenish-gray lichen with a leafy (foliose) appearance. One of our more common lichens, it is often seen on the upper branches of trees, and was particularly abundant on the ash trees that died from emerald ash borer. I don’t know if the birds chose this species of lichen in particular or, being common, it is just found most often. It is also interesting that the birds seem to apply the lichens to the nest in an upright position, with the top facing outward, so they look like they could be growing on the nest.

Come birding at the Garden! Take a birding class; join a group, and check your finds against our bird list.

Although this process is fascinating, it is not restricted to hummingbirds. One of the other breeding birds at the Garden utilizes a very similar nest construction technique to hold its three to five small eggs. The blue-gray gnatcatcher, another tiny bird (that somewhat resembles a miniature catbird in appearance and sound), also constructs a nest out of soft plant fibers, including spiderwebs, and applies lichen to the outside of its nest. A nest of this species, a little larger than that of a hummingbird, was found on a branch of one of the locust trees growing in a Garden parking lot.

PHOTO: A female ruby-throated hummingbird (males have the ruby coloring) enjoys a sip of salvia nectar in Circle Garden in summer.

A female ruby-throated hummingbird (males have the ruby coloring) enjoys a sip of salvia nectar in Circle Garden in summer.

PHOTO: A blue-gray gnatcatcher at the Garden; females look similar, but are less blue.

A blue-gray gnatcatcher at the Garden; females look similar, but are less blue.

If you’re lucky, you might find the nest of one of these birds during the nesting season, but if not, keep an eye out for little bumps, lumps, and knobs on bare branches in winter. You might get lucky.

Come #birdthepreserves with the Forest Preserves of Cook County. View our list of upcoming events for free events near you.


©2016 Chicago Botanic Garden and my.chicagobotanic.org

Do you see something pushing up from the ground that looks like the claws of some creature in a zombie movie? Does it smell bad too?

Happy spring! This charmer is the first native wildflower of a Chicago spring: the skunk cabbage (Symplocarpus foetidus).

PHOTO: A skunk cabbage blooms in early March in the McDonald Woods.

A skunk cabbage blooms in early March in the McDonald Woods.

It’s a biologically intriguing, ecologically brilliant prelude to the wildflower riot about to burst forth on forest floors from the McDonald Woods at the Chicago Botanic Garden to area preserves.

It’s a welcome sight to Boyce Tankersley, the Garden’s director of living plant documentation, who pointed out skunk cabbage as we walked through the McDonald Woods, the 100-acre restored and protected natural area that is home to at least seven state-listed threatened or endangered plant species.

Skunk cabbage’s appearance means that the trilliums and bloodroot are not far behind. And spring beauties, star-flowered isopyrum, and cardamine, also called bittercress. Within a few weeks, depending on the weather, forest floors will be carpeted with wildflowers, courtesy of the sun streaming onto the earth before the trees leaf out and block it.

Skunk cabbage isn’t conventionally pretty. What you see are the claw-like pointed red-striated hoods called spathes surrounding a nub studded with blossoms. The plant creates its own heat, even amid snow and ice. The temperature inside the hood can be 95 degrees hotter than outside.

Thermogenesis is the goal for skunk cabbages, titan arums, and other “warm-blooded” plants.

The heat creates the plant’s signature smell, a cross between a skunk (hence the name) and rotting meat. This turns skunk cabbage into a paradise for flies, which seek out rotting meat where they can lay their eggs.

“It’s kind of got the rotten vegetation look going on,” Tankersley said. “It’s warm, which means there’s something decomposing, from a fly’s perspective. And then of course it smells bad. So there’s your triple play: ‘You need to come here.’”

And flies do come to skunk cabbage. They flit inside the hood looking for rotting meat, then emerge covered with pollen. Then they fly inside another skunk cabbage, and pollinate it.

Honeybees are the plant’s other major pollinator. They are attracted to skunk cabbage because it is a rare, early source of pollen, on which they feed. You can see a honeybee in pollen-coated action inside a skunk cabbage in the video below by the Illinois Natural History Survey: 

Watch the Skunk cabbage video on YouTube.

Skunk cabbage is picky about where it grows. You can only find it in fens, wet woodlands, and other places where water is moving beneath the soil’s surface. At the Garden, they’re alongside the path through the McDonald Woods. Outside the Garden, a good spot is the River Trail Nature Center, a Cook County forest preserve in Northbrook.

And while you can see skunk cabbage now, the other wildflowers are still holding back. That’s because they’re smart.

“They’ve seen these warm temperatures and then had the weather snap on them,” Tankersley said. “Genetically, they know if they hope to survive, they can’t come out with the first warm weather.”

Which is why native wildflowers are almost never felled by a sudden freeze.

PHOTO: Prairie trillium (Trillium recurvatum).

The elegant—and less smelly— prairie trillium (Trillium recurvatum) is our next bloom to look for in the woods. Keep an eye out!

In the next weeks, the wildflower show will be on in full force. In addition to the McDonald Woods, you can catch it at forest preserves, where invasive species like buckthorn and garlic mustard are regularly removed, as they are at the McDonald Woods. Some of my Forest Preserves of Cook County favorites not far from the Garden are Harms Woods near Glenview and LaBagh Woods near Cicero and Foster Avenues on the city’s Northwest Side.

But the previews are open now. And it’s a real stinker.


©2016 Chicago Botanic Garden and my.chicagobotanic.org