A day in the field:
Developing a species status assessment for the Henslow's Sparrow in North Carolina
When I decided to go to graduate school, I knew I wanted field work to be a component of my research. I had been working a desk job for almost four years, and I craved the opportunity to be in-tune with nature. More than that, I wanted to be involved in all aspects of the research process—from data collection to analysis to communicating my results. In the spring of 2020, I was accepted at North Carolina State University and I was offered the chance to study the Henslow's Sparrow for my research project—it wasn't the exotic, tropical bird research I had initially envisioned, but the project was too good to pass up!
For my PhD research, I am assisting the North Carolina Wildlife Resources Commission in developing a species status assessment for Henslow's Sparrows in North Carolina. The Henslow's Sparrow is a grassland specialist species that generally breeds in midwestern states. Populations are declining all across the species' breeding range, thus the Henslow's Sparrow is considered a species of high priority to state conservation managers. The grassland habitats that Henslow's Sparrows depend on for their nesting sites are rapidly disappearing from the landscape due to habitat loss and climate change. There's actually only one known breeding site for Henslow's in North Carolina. The property is called the Voice of America Game Land—it is owned by the North Carolina Wildlife Resources Commission and is maintained as grassland habitat through a rotation of prescribed fire. My research focuses on estimating this population's size, growth rate over time, its response to the fire management on site, and its genetic structure. Combined, this information will illuminate the current conservation status of the Henslow's Sparrow in North Carolina.
I've just begun my third season of field research on the Henslow's Sparrow at the Voice of America Game Land. Here, I share what a day in the field is like for a PhD student of applied ecology.
Let me begin by saying it is impossible to describe a "typical" day in the field, because every field day is different—some days we catch and band birds, other days we observe birds and conduct point count surveys, others we measure the vegetation structure throughout the site, and every so often we get rained out and can't work! I consider the most exciting days to be the ones where we fit radio tags onto our Henslow's. On these days, we begin work before sunrise and we search for singing Henslow's on the horizon.
On a nice morning in April, the whole field is alive with the tiny chirps of male Henslow's defending their territories. For a species that is considered a conservation priority, it's something special to experience so many Henslow's in one place, singing from all sides.
Searching for Henslow's Sparrows on a chilly morning in April. Photo: Brittany Salmons.
A Henslow's Sparrow, singing his heart out. Photo: John McKay.
It usually doesn't take long before we find our first target. The Henslow's that we put radio tags on are confident males, full of bravado. They perch themselves up on a dead stem, just above the grass. They throw back their heads and let out their proud little "chirp".
Target acquired.
Once we've found our Henslow's Sparrow of interest, catching him is fairly simple. We assemble a six-meter mist net nearby his perch. With a little audio playback, we can lure the male into the net in a matter of seconds. We will gently lift the bird out of the net and place him in a bag while we get set up to process the bird. We'll take a few measurements, band him, and fit him with a radio tag.
Top: setting up a mist net set up in the field. Bottom: a Henslow's Sparrow in a bird bag waiting to be processed.
Banding a Henslow's Sparrow with colored bands. Each banded bird receives a unique combination of three colored bands so we can identify individuals in the field from a distance. Left photos: Brittany Salmons. Right photo: Michelle Jewell.
Processing our Henslow's Sparrow involves a few steps. We begin by fitting him with some new "bling"—a USGS bird band. This little silver anklet has a unique number combination on it. If our Henslow's Sparrow is recaptured at another location, those researchers would be able to determine where this bird was banded previously. Then we add three colored bands to the bird's legs. The unique color combination is our way of identifying individual birds in the field from a distance. Next, we'll take a few measurements—the bird's wing length, its mass—and we'll age the bird by looking at the quality of its plumage. Finally, after the bird has been processed, we can fit him with a radio tag.
A Henslow's Sparrow wearing a solar-powered radio tag. When released, we can track this birds movements around the grassland habitat. Photo: Michelle Jewell.
On our Henslow's, we are deploying solar-powered radio transmitters. These tiny "backpacks" have a thin antenna that sticks off the rump of the bird which will transmit the bird's location every few seconds, so long as the solar panel is receiving some sunlight. Tags are designed to weigh no more than 3% of the bird's bodyweight, so they don't affect its movement or behavior. With these tags, I am able to trace individual Henslow's movements throughout the Voice of America Game Land. I can then calculate the bird's home range size (the total amount of area this bird uses during the breeding season), I can get a good idea of its habitat use at the site, and I can potentially see how the home ranges of neighboring birds overlap each other. This information is one piece of the puzzle to help us understand the status of the species in North Carolina.
With all of the research being conducted and the advancements in technology, we know we have the power to conserve threatened species, like the Henslow's Sparrow. But we need the right information to guide our management efforts. This project will help conservation managers in North Carolina protect a precious species that is increasingly threatened by the impacts of climate change.
In three years, I've gotten so much out of my PhD program. Through this project I have learned about spatial ecology, population dynamics, conservation genetics, and habitat management—all skills that I am excited to use to help conserve other threatened species in the future.
And I am proud to say that I've developed an appreciation for sparrows.