A December 2016 Field Note by Vera Leopold, TWI Grants Manager/Development Associate and avid birder
Walking along the dry streambed beneath large sycamore trees, a sweet, lazily descending warble high above me suddenly arrested my attention. Just as I stopped and looked overhead, a tiny, brightly colored bird zoomed down to a low branch near me to inspect the intruder. It was a male Yellow-throated Warbler, the owner of the song and holding a caterpillar in his bill, no less—evidence of nesting for this species more commonly found in southern Illinois.
The sighting was the latest thrill at the Wetlands Initiative’s Hickory Hollow tract during what I call the magic hour: that time shortly after sunrise at the height of summer when the woods and fields are filled with slanting light and birdsong, and the human world hasn’t yet begun to stir. This past June, I was privileged to be out at that hour doing bird surveys on this new parcel at TWI’s Dixon Waterfowl Refuge. With savanna and prairie restoration here only in its first year, there was already plenty of magic happening.
In 2015, the U.S. Fish and Wildlife Service awarded TWI a two-year Neotropical Migratory Bird Conservation Act (NMBCA) grant in support of the Hickory Hollow restoration. This highly competitive program funds work that benefits bird species of conservation concern that breed in North America in the summer and winter in Central or South America (“Neotropical migrants”). We proposed to conduct bird surveys on the Hickory Hollow tract before, during, and after restoration to monitor how migratory bird populations responded to the improved habitat. As one of our birders-in-house with surveying experience, I was up for the task.
We chose to do point-count bird surveys, which involve standing in one place and recording all the birds you see or hear for a 10-minute period. The protocol for these surveys comes from the Illinois Natural History Survey’s Critical Trends Assessment Program, which (in part) surveys bird populations in grassland, forest, and wetland areas across the state. Using mapping software in the office, TWI’s Senior GIS Analyst Jim Monchak and Senior Ecologist Dr. Gary Sullivan selected nine points at random within Hickory Hollow before restoration began in 2015, seeking to cover all the major projected or current habitat types. We set multiple points in the future savanna and prairie zones, since these are the main focus of TWI’s restoration work at the site.
Then came the real fun: discovering what was out there. In June and early July 2015, I used a handheld GPS unit to find each of the nine points on foot and conduct “pre-restoration” surveys there. Because the site had no real trails yet, reaching some points meant wading through stinging nettles or carefully crossing a sea of soybean plants. The non-forested portions of Hickory Hollow were farmed for soybeans before TWI acquired it in late 2014, and we allowed the farmer to complete one final crop in summer 2015 to leave a “blank slate” for when restoration began in the fall.
I didn’t find much in the prairie restoration zones that were still soybean fields, but I encountered a good assortment of forest birds in the riparian woodland such as Tufted Titmouse, Rose-breasted Grosbeak, Eastern Wood-Pewee, Wood Thrush, Red-eyed Vireo, and Yellow-billed Cuckoo. I also observed a healthy number of Pileated Woodpeckers, Illinois’ largest woodpecker and close relative to the likely-extinct Ivory-billed Woodpecker. As we suspected, the riparian woodland that follows the intermittent stream through Hickory Hollow was already supporting a diversity of birds. By adding this area to the Refuge, it’s now permanently protected, and TWI will only need to enhance the habitat by removing invasive and weedy species rather than conduct full-blown restoration.
Returning to the points again in June 2016 was even more exciting. TWI began intensive restoration of Hickory Hollow in September 2015, so the former soybean fields had been seeded with dozens of native plant species. We also thinned small or weedy tree species out of the savanna restoration zones to reestablish the more open canopy characteristic of healthy savanna.
When I walked the site in the early morning of June 8, the prairie areas had changed a lot, with annual native plant species colonizing them (soon to be replaced by the perennial natives we planted). But the savanna points were so different I didn’t recognize them. In 2015, I was standing in the shade, surrounded by saplings; in 2016, I found myself in a fairly open clearing with beautiful views of the large oak trees and nearby fields.
The birds had noticed the change, too. As I began my timed survey at Point 8, for example, an Orchard Oriole sang loudly from the top leaves of an oak down the hill, a Lark Sparrow flew up to an open branch less than 30 meters west of me, and a pair of Northern Flickers hitched along a trunk to the north. None of these birds was present at this location just a year earlier. The newly thinned savanna areas seemed to be bustling with avian life, and initial analysis of the survey data bore this out: I found a total of 12 species at the savanna points in 2015 and 25 species in 2016, more than twice the species diversity!
A number of pairs or families of birds were also present in the new savanna zones, indicating probable breeding. I saw not one but two family groups of Baltimore Orioles at the woodland edges and learned that the parents make an odd kind of mewing sound when moving about with their fledged young, perhaps a family contact call. And I unexpectedly witnessed the beautiful song flights of Horned Larks as I walked through the prairie-in-progress between Points 3 and 4, their tinkling notes falling to my ears as they flitted high across the sky.
I’ll be returning in the coming years to continue to monitor the changes in the site’s birdlife. TWI’s intensive savanna and prairie restoration work at Hickory Hollow runs through December 2018. A network of public trails and a special overlook are planned, with construction beginning in 2017.
What other thrills await this surveyor (and other visitors) during the magic hour in future summers at Hickory Hollow? Time, and more restoration, will tell.