It is 6:30 am on a Wednesday morning, and I am walking miles across prairie grasslands, waving a long stick. What am I doing, you ask? Well, I volunteered to help NIU Master’s student, Heather Herakovich, locate grassland bird nests at Nachusa Grasslands. Heather’s research studies how bison are impacting grassland bird nest density and survivorship. In her research, Heather compares the land that bison now roam to non–bison grassland plantings. The various bison/non–bison fields in her comparison study were remnant or restored in similar years.
Heather gave me my own ‘search stick,’ (light–weight and about a meter long) and my job was to space myself a few feet from her and gently wave and probe the vegetation in front of me as I walked forward. The task is not too complicated for me and is actually rather relaxing on this beautiful morning. There were three of us that morning, (Heather, Jessica Fliginger & I) and we walked in transects (long straight lines) trying to flush birds from their nests. We spent two hours on each designated field in the study.
First, we walked for two hours in an unburned field in the Hook Larson Unit. It was harder to walk through this unit, since last years standing dead vegetation was all underfoot. However, the Henslow’s Sparrow prefers to build its nest in this dense layer of dead grass and plants and I would love to find this bird nesting here. During our two–hour walk, we did not find any Henslow’s nests, but we did hear them calling and we spotted a few with our binoculars. This was pretty exciting for me to hear so many Henslow’s in this field, because the conservation status of this grassland bird is listed as ‘near threatened’ by IUCN.
After two hours of hiking back and forth, back and forth, we found ZERO nests in the unburned field. Yeah, if research were easy, I suppose everyone would be doing it! I was a little disappointed, but mid–May was still early in the nesting season, so more nests could be spotted in future weeks. So, we headed to the next field in Heather’s study, Hook Larson West. This field was quite different from the one we had just walked, for it had been managed with a controlled burn. The ground here was very easy to see and also easy to traverse, with young prairie plants only several inches high.
Our first task was to relocate a Lark Sparrow nest that Heather had found only three days before. When Heather finds a nest, she takes a GPS reading so she can easily find the nest throughout the season. We followed the GPS reading, but no mother bird flushed from the nest when we approached. Hmmm . . . not a good sign. In fact, we searched for the nest for a bit, already suspecting it had been abandoned. Our first clue that there had been trouble was a lone Lark Sparrow egg on the ground in the nest area, with a hole in the egg — probably caused by a predator. When we finally located the nest, it was empty, clearly abandoned. Now that the nest is empty, on her next visit, Heather will return to this nest with a Robel pole and quadrat to quantify the density of vegetation around the nest (ie. how visible the nest may be to aerial predators) and to quantify the plant composition around the nest.
While searching for the nest around the GPS coordinates, I made a fun discovery and spotted a tree frog in the vegetation — either a Eastern Gray or a Cope’s Gray.
While transecting this unburned unit, we heard the insect–like call of the Grasshopper Sparrow and the song of the Dickcissel. We also saw a Killdeer several times, but not its nest. There was a lone Lark Sparrow egg found on the ground, but no more nests were spotted until the very end of our time in that field. I actually flushed the female out of the vegetation and first spotted the nest. Very exciting!
Once the nest was found, Heather had to work quickly, so the mother was not away from the nest too long. Heather instructed us to not touch any vegetation near the nest with our hands, only using our search sticks to move the plants. Something I learned from Heather that morning is that predators can follow our scents to locate the bird nests, so we have to be careful and leave as little as possible.
The mother left the nest so quickly, but Heather noticed the bird’s tail feathers and believes the identity can be confirmed as a Lark Sparrow. There were four eggs in the nest and three eggs appeared to be from a Lark Sparrow, while the last egg was from a Cowbird. We glanced at the nest contents quickly, snapped a few photos, and then walked a good distance away from the nest to record the important data. Heather keeps track of the species, the date & time, the number of eggs, the number of young & whether the mother was on or off of the nest.
Before we parted for the day, Heather took Jessica and I to see another nest found in the Sand Farm planting. This nest belonged to a Red–winged Blackbird.
If you would like to volunteer to help Heather search for bird nests or if you are interested to read more about Heather’s research, visit her website at http://www.bios.niu.edu/jones/lab/heather_herakovich.html