More than one in four North American birds have disappeared since 1970, signaling the development of potentially deeper ecological problems in the region, according to a new study co-authored by director of the Georgetown Environment Initiative Peter Marra.

The study, published in Science magazine on Sept. 19, tracked populations of more than 500 bird species across multiple ecosystems and found that there has been a decline of 2.9 billion breeding adult birds in North America in the last 49 years. 

The combination of citizen and professional scientists participating in bird-watching, in addition to more than 10 years of data from NEXRAD, a network of weather radars operated by the National Weather Service, paints a clear and bleak picture, according to Marra, who is also a professor in the McCourt School of Public Policy. 

“Just in the last 10 years, we are seeing this decline,” Marra said in an interview with The Hoya. “By incorporating all of these different types of data, it made us depressingly confident in the results.”

Birds are an indicator species, meaning they reflect the overall health of an ecosystem and can serve as a warning sign for larger ecological problems in the future, according to Marra.

“When something is going wrong with them, that means something below them in that complex food web is also going awry,” Marra said. “That means that there is something unraveling in the ecosystem.”

Marra’s research included one of the largest surveys of bird populations to date, as the analysis incorporated data from citizen scientists, professional surveys and weather radar to track migration patterns. The study was authored by Marra and researchers at seven North American institutions, including Cornell University, the American Bird Conservancy and the National Wildlife Research Centre.

Many co-authors of the study, including Marra, are advocating for the Recovering America’s Wildlife Act of 2019, a bill that allocates $1.4 billion for state and territory developed conservation strategies. The bill is sponsored by Rep. Deborah Dingell (D-Mich., SFS ’75, GRD ’98) and was introduced in the House of Representatives in July 2019.

“We need bold solutions that will put forward state-based conservation efforts and safeguard wildlife from further decline. RAWA is that bold solution,” Dingell wrote in an email to The Hoya. “Supported by more than 100 Members of Congress, this bipartisan legislation will provide financial resources for state agencies so those in the field can do everything possible to protect species most at risk.”

Conservation requires infrastructure changes in addition to policy action, according to Michael Parr, president of the American Bird Conservancy and co-author of the study.

“Among other priorities, we’ve got to manage our public lands better for nature, restore laws that protect birds, and massively increase support for habitat conservation outside the U.S. to protect tropical forests where many of our birds winter,” Parr said in a Sept. 20 news release.

The most devastating finding in the study is the decline in common birds, which are integral to their ecosystems, according to Marra.

“We all made this commitment to keep common birds common. What this report says, unfortunately, is that it’s now the common birds that have declined the most,” Marra said. “These species have now declined significantly, suggesting that there are these broad-scale things that are eating away at the avifauna.”

While the study did not examine causality explicitly, it is important to consider the role of climate change in habitat destruction as a major factor in the population decline, according to Marra.

“Drying patterns in the Caribbean are totally changing when birds leave,” Marra said. “Birds that are migrating farther distances are leaving the wintering grounds in poorer condition, and there’s higher mortality on those birds.”

Marra noted the importance of conservation efforts in everyday life in supporting the bird population, emphasizing the potential for conservation on Georgetown University’s campus.

“We need to minimize these general threats that are impacting birds and other organisms,” Marra said. “Even in human-dominated landscapes like the Georgetown campus, making sure that we are doing things here that are environmentally friendly.”