Archives For Nature in View

Echoes of a Silent Night

Senior ecologist Jim Steffen describes his close encounters with curious and beautiful bats.

Jim Steffen —  October 29, 2014 — 2 Comments

A few years ago, in early spring, I was traveling through McDonald Woods at the Chicago Botanic Garden, searching for some of the flat-bodied crab spiders (Philodromus) that typically spend the winter in communal groupings under the loose bark of dead trees. Upon reaching a small stand of dead American elm trees, I began to lift the loose remaining bark away from one of the trees to see if any spiders were present.

As I gently pulled the bark away from the trunk, a tiny black hand reached up over the top edge of the bark. It quickly became obvious that there were more than spiders under this bark!

Although I was a little startled to have this hand slowly reach out in front of my face, I immediately realized that this piece of loose bark was the day roost of a silver-haired bat. The silver-haired bat is a medium-sized bat that is a dark chocolate brown or black with white hairs scattered among the dark hairs on its back. I gently released the bark so as not to disturb the napping bat any more than I already had. This is just one example of why it is important to maintain at least some dead standing trees in our woodland communities.

PHOTO: Silver-haired bat.

A silver-haired bat curls up tightly on a tree in McDonald woods. Photo by Jim Steffen

Even though bats are fairly common mammals in our area, since they are almost totally nocturnal, we don’t get to see them all that often—especially at close range, when we would be able to admire their delicate form and attractive appearance. Bats are in the order Chiroptera, roughly translated as “hand wing,” and are the only mammals that are actually capable of true flight (unlike flying squirrels—which we also have at the Garden). 

You might be familiar with another group of small mammals known as shrews. Shrews are mouse-like animals that are actually carnivores that feed heavily on invertebrate populations. Although bats may have varied diets around the world, here they are primarily insect eaters, much like shrews with wings.

When I was in college studying mammology, we used to go out at night and look for streetlights where there were large numbers of moths and other flying insects attracted to the lights. We would then take out our car keys and jangle them around to make high-pitched sounds with the keys clinking together. These high-pitched sounds would simulate the high-pitched sounds produced by the echolocation sounds produced by hunting bats to locate their prey. (Unless we are equipped with special listening devices, we are not able to hear the sound of bat echolocation.) Often times, many of the moths would begin flying erratically, or drop out of the air as though they had been struck with a stupefying charm from Harry Potter’s wand. These moths have evolved defensive tactics to help them avoid being eaten by bats by flying in erratic patterns or closing their wings and dropping if they heard the sounds of an approaching bat. 

PHOTO: Eastern Red Bat

An eastern red bat (Lasiurus borealis) clings to black landscape fabric at the back of one of the buildings here at the Garden. Photo by Jim Steffen

Many years later, while removing invasive garlic mustard from our oak woodland a few summers ago, I came upon an oak tree with a broken branch. All of the leaves on the branch had turned a bright reddish-brown that stood out against the backdrop of all the other green foliage. On closer examination of the branch, I spotted a female eastern red bat hanging upside down, in typical bat fashion, with its single offspring clinging to it. I don’t know if the bat was aware of it, but this dead branch provided the perfect camouflage for her rich color.

This made me think about how these mammals perceive the world. Do bats have color vision, and was this red bat able to tell that the dead branch would be such a good match for its own color? Most nocturnal animals tend not to have color vision, since color does them little good in the dark. Most bats are various shades of brown, black, or gray. (It is a different story for birds that are mostly active during the day and use bright colors as a means of attracting mates or advertising territories.)

PHOTO: Lasiurus cinereus (hoary bat).

Hoary bat (Lasiurus cinereus by Daniel Neal [CC-BY-2.0], via Wikimedia Commons

We have five species of bats that are likely to be seen at the Garden. Some of them are summer residents, like the little brown, big brown, and eastern red bat, while others are mostly migratory species, like the silver-haired and hoary bats that show up during their spring and fall migrations. Years ago, in the late fall, while using fine nets at night to capture owls for attaching U.S. Fish and Wildlife Service bird bands, I often caught many of the large, hoary bats migrating south for the winter. These large bats have an attractive frosted appearance with a mix of white and reddish hairs all over their bodies.

While I was studying birds in the tropical rain forest of Central America, I often encountered small colonies of bats hanging at eye-level, under the broad leaves of Heliconia plants. I think these wide, tent-like leaves were chosen mostly for the protection they gave the bats from the torrential downpours that occurred every day. However, the bats we find here are either solitary animals, like the red, silver-haired, and hoary bats that live solitary lives in the woodlands and forests, or they are colony-forming bats, like the little and big brown bats, that search out attics, barns, or large hollow trees where they gather in groups to raise their young.

Some of the bat species also search out caves or old mine shafts during the wintertime, where the subterranean habitat provides moist, stable conditions with above-freezing temperatures suitable for hibernation. It is possible to construct bat houses that, if placed in the proper locations, can attract and support colony-forming bats during the summer.

We have several of these bat house installed on buildings around the Garden. This summer, one of those houses contained half a dozen bats—probably little browns. It is best to place bat houses in full sunlight, since the bats have high body metabolisms and prefer very warm conditions for roosting during the summer. Think you’d like to build a bat house? Construction details can be found at the Bat Conservation International website at batcon.org.

PHOTO: Flying squirrel.

Another local flier, this very tame flying squirrel enjoyed a snack of walnut with his photo op. Photo by Jim Steffen

Bats are more than curious and beautiful creatures; they are also tremendously important components of a healthy environment. They are extremely important control agents of insect populations. Many of the insect species they eat are harmful crop pests, like army cutworm, or irritating or disease-carrying species like mosquitoes. Some bats can consume more than 1,000 mosquitoes in a single night! Bats are in trouble now for many reasons—not the least of which are climate change, exotic diseases like white-nose syndrome, and habitat loss.

Although bats are seldom seen and often have scary, erroneous wives-tales associated with them, we should be working hard to correct the problems that might lead to a truly silent night.

©2014 Chicago Botanic Garden and my.chicagobotanic.org

Creepy, gooey, stinky, thorny…for some plants, every day is Halloween. Find out more in our Spooky Plants infographic!

Spookygraphic: an infographic about spooky plants

©2014 Chicago Botanic Garden and my.chicagobotanic.org

Fall on the Prairie

Carol Freeman —  October 15, 2014 — 2 Comments

While summer blooms elsewhere are winding down, the Dixon Prairie is still alive with many fall flowers.

PHOTO: Red Admiral butterfly.

Warm fall days bring out the butterflies; this red admiral is enjoying a New England aster. ©Carol Freeman

Asters, sawtooth sunflowers, gaura, and goldenrod are going strong. All of them are abuzz with bees and other insects. Grasshoppers dance from plant to plant. Butterflies fuel up for a last fling or long journey.

Dewy milkweed seeds blow in the wind. ©Carol Freeman

Dewy milkweed seeds blow in the wind. ©Carol Freeman

Grasses, some with tiny fragrant flowers, sway gracefully; many have grown more than 7 feet tall in this one growing season. Early morning dew transforms the seedheads into works of art. Silken strands of unseen spiders glow in the sunlight. Flocks of goldfinches munch on seeds, stocking up for winter, chirping their happy tunes, while shy sparrows occasionally pop up from the shadows, giving us a glimpse of their subtle beauty. Milkweed seeds blow gracefully in the wind.

The prairie truly must be walked to be appreciated. There is so much diversity, and so many stories to tell.

Touch a compass plant leaf on even the hottest day and it will be cool to the touch—with roots going down 14 feet, they pull up water that is chilled underground.

Monarchs live in symbiosis with milkweed plants (as do many other insects). Look closely and you may see a whole world on a milkweed plant.

Surprises can be anywhere—a hummingbird zipping by for a quick sip, a great blue heron flying overhead, drama as a hawk dives down to grab a vole. Fall on the prairie is colorful, alive, and a place of great wonder not to be missed.

Unseen spiders create artwork that catches the early morning dew. ©Carol Freeman

Unseen spiders create artwork that catches the early morning dew. ©Carol Freeman

Seed heads magically transformed with early morning dew. ©Carol Freeman

Seedheads are magically transformed with early morning dew. ©Carol Freeman

Grasshoppers dance from plant to plant. ©Carol Freeman

Grasshoppers dance from plant to plant. ©Carol Freeman

Gaura flowers still attract hover flies. ©Carol Freeman

Gaura flowers still attract hover flies. ©Carol Freeman

Resident Goldfinch stock up on the abundant seeds in the prairie. ©Carol Freeman.

Resident goldfinches stock up on the abundant seeds in the prairie. ©Carol Freeman.


©2014 Chicago Botanic Garden and my.chicagobotanic.org

Adriana’s Bird of the Day is the Kingfisher

Or, everything I needed to know about birding I learned at the Garden

Adriana Reyneri —  October 13, 2014 — 1 Comment

A partial transcript of my first official bird walk:

Me: What was that call?

Expert birder: A chipmunk.

Me: What’s that big brown thing in the branches? It’s shaped kinda like a hawk.

Expert: Dead leaves. We call that a fake-out.

Me: Right.

Expert: Do you hear that rattle? I hear a kingfisher!

I really do not hear the rattle, but I feel a rush of excitement as I chase my guide along the trail of the Barbara Brown Nature Reserve at the southeast corner of the Chicago Botanic Garden. The tree-lined pond is one of many different habitats that make the Garden an excellent place for birders experienced and otherwise. Adding to my great fortune are golden sunshine—lighting the first red, orange, and yellow leaves of autumn—and the presence of Al Stokie, who comes to the Garden every week to report on shorebirds and other avian visitors. I’m tagging along on one of his early morning surveys and gleaning basic principles of birding.

Several area bird clubs—including the Lake County Audubon Society (an Illinois Chapter of the National Audubon Society) and the Evanston North Shore Bird Club—welcome beginning birders to their regular meetings and field trips.

PHOTO: Al the birder.

Al Stokie comes to the Garden weekly to monitor bird populations. He files his counts on the IBET website.

It’s seasonal

Our first stop was the expansive deck of the Kleinman Family Cove, one of Al’s favorite spots for viewing the North Lake. In just a few weeks the surface would be filling with ducks stopping to rest on their way south for the winter. They’ll be followed in November by grebes and red-breasted mergansers. Native plants surrounding the cove attract a variety of birds, but most of the tiny warblers left for warmer climes weeks ago. McDonald Woods, a restored native oak woodland, is the place to go in the spring to catch the warblers’ return and, if you’ve got really good eyes, a place to spot owls in the winter.

“It’s all seasonal,” says Stokie. “Every month of the year you can go out and see different things.” I like that idea: The Garden as an ever-changing landscape of birds.

It’s all about the food

We continue along the North Lake road and find two more potential hot spots for birds. A peninsula of land supports a grove of evergreens loaded with cones—a big draw for wintering pine siskins and—if you’re lucky—crossbills. Down the road a bit, you come to an Emergency Call Box. Look past it and you’ll see large junipers growing along the exterior wall near the Garden’s northwest corner. That’s where a very rare Bohemian waxwing, feasting on the juniper berries, was last seen in the Garden.

 

PHOTO: Egret in flight.

An egret in flight at the Barbara Brown Nature Reserve at the Garden

Walk early, and walk often

We are heading south now, along the Garden’s West Road, past a restored streambed, lush with native plants—a habitat that provides lots of seeds and insects. The best time for birding tends to be the four hours or so following sunrise, so getting up early can have its rewards. Persistence also pays off, Al explains: “It’s a matter of odds. If you look in one spot ten times, you’ll probably see something.” Just then we catch sight of movement in the shrubs. Al first identifies the little bird by the way it waves its tail up and down—an (ahem) telltale sign of the palm warbler, one of the last warblers to head south for the winter.

The Joseph Regenstein, Jr. School of the Chicago Botanic Garden also offers guided bird walks. Learn more about bird walks taking place at the Garden this fall.

PHOTO: Bird enjoying seeds from dried seedheads.

Seedheads from native plantings along the restored Skokie River corridor provide ample food for birds.

It ain’t easy—even for the experts

Flocks of goldfinches—displaying olive drab winter plumage—are diving in and out of the tall forbs and grasses of the Dixon Prairie. Niche ecosystems within the prairie provide food and shelter for many different types of birds at different times of the year. Hummingbirds are drawn to the red blooms of royal catchfly (Silene regia) that flower on the dry gravel hills in the summer, while the prairie wetlands attract swamp and other types of sparrows. Turns out sparrows can be tricky to identify, unless—as it happened—one stops to feed on the path in front of you. Al identifies it as a white-crowned sparrow. “For every bird you identify, there are probably five or six you do not get a look at—or you get a lousy look and don’t know what it is,” Al Stokie.

Watch the weather

Shorebirds are drawn to the southwest corner of the Garden, an overflow area for the Skokie River with plenty of muddy shores. “Old Faithful,” a white egret nicknamed by Stokie, comes in for a landing, joining a well-camouflaged green heron and a killdeer, the hardiest of the shorebirds and a late migrator. Most of the sandpipers—Al’s particular interest—have left already. In a flash of movement, the heron fishes a frog out of the water. We witness its slow death through our binoculars, though I have to admit I am still struggling to focus and aim mine. Standing on the sunny, breezy path it’s hard to believe a cold front will be moving through in a few days. That’s likely to bring in a new wave of migratory birds, in this case, sparrows.

Find a mentor

A beginning birder who comes out on his own with a bird book and a pair of binoculars is likely to be overwhelmed, Stokie said. This makes perfect sense to me. Without Al at my side, so much of the experience would have…er…flown right over my head. Take that belted kingfisher back at the Barbara Brown Nature Reserve. While I was still craning around, listening for the rattle, Al had sighted the bird perched in dead branches across the pond. Handing me his binoculars, he asked, “Do you see something, blue?” I saw flashes of blue and white, and the shape of a stocky bird, with a big head.” Okay, it was still slightly blurry, and I had to close one eye to make it out, but I saw it! The moment was recorded for posterity when Al filed his count online. I felt a ridiculous burst of pride when I read the mention, “Adriana’s bird of the day is the kingfisher.”

Join us from 7 to 9 p.m. Friday, November 14, for an Owl Prowl at Ryerson Woods. Click here to register online.

PHOTO: Another great birding location.

Al looks across the North Lake toward the Fruit & Vegetable Garden for signs of bird activity.

For more information:

Experienced birders David Johnson, Jeffrey Sanders, and Alan Anderson, as well as Jim Steffen, the Garden’s senior ecologist, also helped me gather information for this report. To follow sightings by Al and other local birders, you can go to several websites, including eBird (ebird.org/ebird/places), which designates the Garden as a hot spot, and IBET (groups.yahoo.com/neo/groups/ILbirds/info).


©2014 Chicago Botanic Garden and my.chicagobotanic.org

If days stay cool and sunny, fall color will continue, peaking this next week. Here’s how it works:

ILLUSTRATION: An infographic on how leaves get their fall color.


©2014 Chicago Botanic Garden and my.chicagobotanic.org