Open Mic: "Ancient" DNA and Extinct Birds
by Nate Swick
At the Mic: Michael Harvey
Michael Harvey is a lifelong birder and a PhD student at the Louisiana State University Museum of Natural Science, where his research focuses on the genetics and evolution of Amazonian birds. His birding and research career were jump-started by ABA programs, including the ABA's periodical for young birders "A Bird's Eye View", the ABA/Leica Tropicbirds, the ABA Young Birders Conference, and an ABA scholarship to VENT's Camp Chiricahua.
Are you curious about how and why the Passenger Pigeon, Carolina Parakeet, Ivory-billed Woodpecker, and Bachman's Warbler disappeared? All of these species are known or thought to have gone extinct in North America in the Twentieth Century, but the reasons for their declines are still unclear. A new research project aims to better understand the disappearances of these species. Michael Harvey, a graduate student, and Brian Smith, a postdoctoral researcher, are both ornithologists and longtime birders based at the Louisiana State University Museum of Natural Science. They are using new techniques to obtain data from old museum specimens.
Here’s how it works. Population genetics, the study of DNA from multiple individuals in a single species, can tell us a lot about the declines of species, and help us to understand why they happened. Specifically, the amount of genetic variation can tell us what the ancestral population size was for each species (how numerous they were before Europeans arrived in the New World). Also, the pattern of variation can tell us if and when significant declines occurred in the past, which could reveal whether they were already experiencing major declines before Europeans arrived.
Researchers can supplement this data about population sizes and declines with geographical information about the potential extent of suitable habitat for each species. Records are available for all of the extinct species from before their disappearances, and these can be plotted on a map. The hypothetical distribution can then be modeled by extrapolating from these points using climate and satellite data from Geographic Information Systems (GIS). The net result is a map of the expected historical distribution for each species. Satellite data can then reveal how much of this potential habitat has undergone human disturbance, which will give an idea of how large a role habitat loss may have played in the declines of each species.
Michael and Brian plan to use these approaches to learn more about how large and widespread populations of these species were historically, determine when and how drastically they declined, and gain insight into the role of habitat loss in their declines.
These spectacular bird species are emblematic of a wilder era in North America. The Passenger Pigeon, for example, is thought to have been one of the most abundant bird species on earth before its decline, with flocks of billions blotting out the sun as they moved between feeding areas in the hardwood forests of the eastern United States. The Ivory-billed Woodpecker was a denizen of only the oldest primary forests, its presence closely tied to the presence of enormous old trees that are just a memory today. The Carolina Parakeet, resplendent with bright green, orange, and yellow plumage, was our only native eastern parrot. The Bachman’s Warbler inhabited our southern swamps, and still frequented some of the most pristine bottomlands at least as recently as the 1960’s. The disappearances of these species have created irreversible holes in our modern biological communities. Understanding these losses is the key to preventing future extinctions.
Michael and Brian are currently trying to raise awareness and funds to complete this study. They are relying on public funding through a new “crowdsourcing” tool for scientific research projects www.petridish.org. To find out more, or to support support the project, please visit: