VERMILLION, S.D. -- When you study the habits of nocturnal birds that nest on gravel patches during a few months each summer, you head to where they often make their temporary home—the flat rooftops of institutional buildings. That’s just where University of South Dakota biology graduate student Gretchen Newberry went this June and July when she set out to research the Common Nighthawk.
In Vermillion, that often meant Newberry spent much of her time surveying the roofs around the USD campus to find the medium-sized, mottled gray-and-white bird. “The majority of nighthawks in this town are on our campus,” said Newberry, a native of Minneapolis, Minn. “They like flat, gravel rooftops so I scouted out buildings where I had seen them fly at dusk.”
Three buildings presented the best opportunities for nest locations: I.D. Weeks Library, Al Neuharth Media Center and Richardson Residential Hall. With permission from the university, and with a facilities management representative in tow, Newberry documented 12 nests and recorded temperature and other weather variables. She said this data will lead to a better understanding of the behavior of the Common Nighthawk and the effect of climate change on the species’ numbers. Newberry, who works in the lab of biology professor David Swanson, also documented nests and adult birds found in area grasslands and in other urban sites such as Yankton and Elk Point.
The Common Nighthawk is one of the most frequently seen of the nightjar family of birds, but their nearly nocturnal habits and the ability to camouflage themselves within their surroundings make them difficult to count in popular bird surveys. In the summer, this bird species is found throughout nearly all of North America and they migrate deep into South America in the winter months. Their numbers appear to be dwindling, however. According to the North American Breeding Bird Survey, populations have declined 59 percent from 1966 to 2010.
Researchers believe a loss of breeding habitat and a decline in the flying insects that make up their food source have contributed to the drop in numbers. Newberry is also interested in how rising temperatures associated with climate change will also affect the Common Nighthawk.
Placing hollow copper balls containing a thermometer on the rooftops, Newberry is able to compare the temperature at rooftop nest sites to nest sites in grasslands. “In terms of climate change, I’m looking at heat stress,” she said. “If temperatures spike further, what are the costs to these animals? If more are nesting on rooftops, there is a big temperature difference between roofs and the shaded areas of grasslands.”
Newberry is beginning the third year of her five-year dissertation research project on the Common Nighthawk. The project will encompass a variety of data collection methods in both rural grassland and urban areas. She will record information on nearly all aspects of the bird’s life, from nest areas and hatchling survival rate to insect foraging patterns.
“A lot needs to be known about these birds,” Newberry said. “I’m trying to build a framework for people who want to study nighthawks.”
Newberry admits to a fondness for her study subject, especially when they puff themselves up to defend their young.
“They are pretty charismatic birds,” she said. “They don’t have weapons or talons like real hawks do. They just have attitude.”
A photo of Newberry with a Common Nighthawk chick that hatched on the roof of the Richardson Residence Hall is available for download at www.usd.edu/press/news/images/releases/Gretchen_Newberry.jpg. The bird species lays its eggs in gravel patches in grasslands and on flat gravel roofs in urban areas.