Science Roundup

Snapshots of our habitat from the perspectives of researchers in the field

Birds Respond to Woodland Restoration

This we believe: restoration is good. “The plant community definitely responds well to natural-areas restoration. I just wondered what was happening in the animal community,” says Scott Meister, animal ecologist with the Forest Preserve District of DuPage County. Meister recently completed a study of the response of songbirds to invasive plant management in woodland areas. And the results are encouraging.

By studying more than 1,000 bird monitoring surveys conducted at 32 DuPage County forest preserves from 1997 to 2003, Meister discovered that birds were noticeably more abundant in “managed” woodlands, where invasive species have been removed and native ecosystems restored, than in unmanaged areas. Even better news is that certain songbird species are thriving in these restored woodlands in statistically significant numbers. Congratulations to: the eastern bluebird, eastern wood pewee, scarlet tanager, indigo bunting, white-breasted nuthatch, red-bellied woodpecker, and northern flicker.

Meister believes these birds have surged back relative to others for a variety of reasons. Many simply prefer the open woodland and savanna that occur once buckthorn, honeysuckle, and other invasive species are cleared out. Others, like the bluebird, are insect-eaters that return once the insects begin to visit the native plants, which grow from dormant seeds in the soil or are planted by restoration staff and volunteers.

But six bird species showed a decline in numbers after the restoration of woodlands. Three of them — the common grackle, house sparrow, and red-winged blackbird — are not of conservation concern, since they can use a wide range of habitats. Of some concern, though, are three rarer species, the ovenbird, wood thrush, and red-eyed vireo. These may benefit in different ways from unburned leaf litter and low brush — which in unmanaged areas are often comprised of problem invasives.

“What I want to stress is that when you conduct a restoration or management program, it’s important to realize what important species are there, and if you are going to destroy their habitat, be quick to restore it if you can,” Meister advises. The Forest Preserve District of DuPage County has planted hundreds of native shrubs in restored areas to give birds that love the underbrush new shelter from the storms.

National watchlist programs name none of these three rarer species as restoration priorities in Chicago Wilderness. Two of them need forests larger than exist here to breed with any regularity. Still, maintaining habitat for these species is highly worthwhile, as is keeping tabs on their needs.

“We were fortunate to have such a large, enthusiastic group of bird monitors,” Meister says. “We had good, hard data from 1997 for our woodlands, grasslands, and wetlands. This should show our volunteers that their work is important.”

— Nancy Shepherdson

Auditors Reveal Grizzly Grassland Picture

During the summer of 2005, what organizers called “the hottest, driest summer in recent history,” most people hid in their homes, cranked the AC, and waited for September. But day after blistering day, 61 volunteer monitors crouched under the sun to record plants as part of the Chicago Wilderness Grassland Audit. When fall finally arrived, they had surveyed 1,614 quadrats in six counties, providing a snapshot of the health of the region’s grasslands.

When project leader Karen Glennemeier of the Chicago Wilderness Habitat Project averaged the “coefficient of conservatism” (or C-value) of species recorded, only 25 percent of the surveyed areas fell in the “good” or “excellent” range. (C-value is a rating based on plants’ need for quality habitat.) The remaining 75 percent ranked either “fair” or “poor.” When Glennemeier factored in the number of species in each quadrat, she found that just a few quality species in a weedy plot could raise its score.

“Of the 20 most abundant species in Chicago-region grass-lands, 13 were non-native, and six were species that require active control through restoration and management,” reported Glennemeier. Surveyors found nonnative woody plants in 30 percent of the quadrats examined, suggesting that many “grasslands” are on their way to becoming overgrown woods. Reed canary grass, an invasive of wetter areas, appeared in 13 percent of plots, covering an average of 41 percent of quadrats where it was found. And the most abundant grassland species? The aggressive yet native tall goldenrod.

“The biggest threat,” says Glennemeier, “is the loss of the processes that maintained the grasslands.” But she estimates that 15,000 acres — nearly 25 percent of the region’s 58,000 acres of grasslands — contain species that suggest a potential for greatness. Regular seasonal burns, a controlled deer population, removal of drain tiles and invasives, and the seeding of native plants, she says, could upgrade thousands of acres from fair to excellent.

— Tegan Jones

Science Reacquaints Chicago Wilderness with Freckled Madtom

Three fish biologists, Philip Willink and James Ladonski of The Field Museum and Frank Veraldi of the U.S. Army Corps of Engineers, had finished a survey for Asian carp in the Chicago Sanitary and Ship Canal in May of 2005 when they headed up into the Des Plaines River. They drove their “shocker boat” up to a set of shallow riffles and turned on the electric current they use to momentarily stun fish to count them. Ladonski netted a fish that caused them all to stop.

It was the freckled madtom, Noturus nocturnes, a catfish only four inches long. According to a study the trio will publish in Transactions of the Illinois State Academy of Science this year, it was last recorded in the Chicago region prior to 1908.

The freckled madtom is occasionally recorded elsewhere in Illinois, in high-quality streams such as Big and Little Rock Creeks and Aux Sable Creek. But to find it in the Des Plaines River, one of Illinois’ lowest-rated streams, was unusual. “Almost all the other fish were common and resistant to degraded habitats and poor water quality. The madtom really stuck out,” says Willink. “It’s a sign that aquatic habitats in the Chicago area may be improving, and other native fishes may possibly regain their former ranges.”

Though the discovery wasn’t part of a systematic survey, Willink considers it a scientific achievement. “If we didn’t have distribution localities and specimens, we wouldn’t know how special the madtom is.” Ichthyologists are compiling a Chicago-region fish database and hope to make it publicly available in a few years.

— Don Parker

Migrating Birds Show Tree Affinities

After flying over the vast agricultural fields of Illinois and Indiana — what ornithologist Doug Stotz of The Field Museum calls “The Great Corn-Soybean Desert” — weary, woodland-dependent migratory birds find the leafy parks and forest preserves of the Chicago region a welcome rest stop and refueling station.

Conservationists wanted to know whether birds especially depended on certain tree species during their stopover. So researchers from Audubon-Chicago Region, The Field Museum, the Chicago Botanic Garden, the City of Chicago, and volunteer birders conducted a three-year study that monitored migrant activity at 19 Chicago-region sites during the beginning, middle, and end of spring migration (the end of April through the end of May).

The researchers found that migratory birds most preferred American elm, hawthorn, and bur oak trees. Their study suggested that birds spent the most time in blooming trees, where they were able to feed on insects eating the trees’ newest, most tender leaves and flowers. Scientists have long known that synchronicity between migration times of bird species and the bloom times of different trees can establish special relationships between the organisms.

The study also found that a group of birds — rose-breasted grosbeaks, Baltimore orioles, blue-gray gnatcatchers, and a variety of warblers — were largely dependent on oak trees. “We don’t have a lot of oak reproduction going on out in the woods and we really need to do something to reverse that trend,” says co-author Judy Pollock of Audubon-Chicago Region.

The researchers recommend planting a high diversity of trees in landscaped areas, and restoring diverse wild woodlands. Because not all trees bloom at the same time, a variety of tree species gives the birds more options for finding food. For homeowners, Stotz says that planting more trees, especially oaks, will help migrating woodland birds. In his opinion, any tree is better than a lawn. “The suburban yards,” he says, “are a huge resource for migratory birds.”

— Chris Hardman

Read more about the study in CW Journal, Summer 2006 (562K pdf download).

The Good News about Secondhand Smoke

Smoke is a familiar byproduct of the prescribed burns used to regenerate the tallgrass prairies of our region. But could that very smoke also have its own beneficial effect on prairie plants?

It took a pair of Chicago-based Australian scientists — Lara Jefferson and Marcello Pennacchio — to ask and then answer that question. Working with Kayri Havens of the Chicago Botanic Garden, they measured the effect of smoke on the germination rates for seeds of a rare local prairie plant, hairy mountain mint, Pycnanthemum pilosum.

The notion of a link between smoke and seed germination isn’t new, explains Pennacchio. “Research conducted during the 1990s demonstrated such a connection among certain plants in Mediterranean environments, but the idea that smoke may improve crop yields is far older,” he says. Indigenous peoples and primitive farmers on three continents all made the connection long ago. “We were just the first to test the idea on tallgrass prairie species.”

The research showed that smoke both promotes germination and inhibits it. Under certain conditions, germination rates may increase by as much as a third after smoke treatment, while under other conditions, the seeds may be destroyed. The length of exposure to smoke and the varied use of water to rinse treated seeds determined success or failure. Complex findings, perhaps; but the conclusion that smoke affects germination is clear.

“The research demonstrates that the effect of smoke, as well as the need for water or rainfall to lessen or eliminate the inhibitory effects of smoke, needs to be a consideration for land managers,” says Jefferson. In practical terms, however, it would be impossible to devise a fire regimen that is uniformly beneficial to all the diverse elements of a tallgrass prairie community, because, as Jefferson acknowledges, each prairie species reacts in its own unique way to smoke.

It may well turn out that the most useful application of these findings will occur in a laboratory or nursery setting, where the selective application of smoke could greatly increase the number of plugs produced from seed stocks, especially for rare species.

— Ron Trigg

Read more about the study in CW Journal, Fall 2005 (1.3M pdf download).