January 10, 2017
Alice Boyle tracks grasshopper sparrows
Grassland bird populations are decreasing, and documenting their movement patterns could help us understand the causes and enhance conservation efforts. Tracking birds is tricky, especially when those birds are tiny, secretive and can fly far without too much effort.
Alice Boyle, assistant professor of biology, is studying the movements of grasshopper sparrows, songbirds that weigh only about 17 grams and nest on the ground in Flint Hills tallgrass prairies as well as other grassland areas in the United States. Analysis of feather samples from more than 100 birds at Konza Prairie and 17 other sites in Kansas and neighboring states helped Boyle create a map of how birds move from one breeding area to another from year to year.
Stable isotopes of common elements occur in variable concentrations around the world and are recycled through food webs. Birds' feathers contain stable isotope signatures that indicate where the birds were when they grew the feathers. The sparrows replace feathers, or molt, while at their nesting sites and leave old feathers behind. Boyle collected and tested feather samples to determine how far apart the birds nest from year to year. A University Small Research Grant from the Office of Research and Sponsored Programs in fall 2015 funded the feather sample analysis.
Boyle found that the sparrows, unlike most birds, don't keep returning to the same nesting spots year after year. Instead, they breed up to hundreds of kilometers away from one year to the next. Other grassland birds may exhibit similar behavior.
Identifying the birds' movement patterns will assist conservation efforts.
"Grassland bird populations in North America have been declining more rapidly than any other group for the past 40 years," Boyle said.
"Kansas is the last stronghold of tallgrass prairie, and if society is to benefit from the ecosystem services offered from biodiversity, researchers in this part of the world must devote themselves to understanding the causes of population change and the ways in which we can reverse those declines," she said.
Boyle has three manuscripts and a funding proposal in development based on the data she gathered. She is working with two K-State graduate students and collaborators from the Rocky Mountain Bird Observatory and Florida State University on the manuscripts. She also plans to present her data at conferences later this year and is an invited speaker at a Gordon Research Conference on "Movement Ecology of Animals" in March, and she wrote a movement ecology chapter for a new ornithology textbook forthcoming from Johns Hopkins University Press.
"Support from K-State was critical to getting this project off the ground," Boyle said.
"With the results, I hope to convince folks at funding agencies more familiar with stay-at-home woodland birds that where and how grassland wildlife move is critical to understanding other aspects of their ecology and critical to their conservation," she said.