The fight to conserve the disappearing black tern
New conservation practices are needed in the fight to save the black tern, a migratory bird that nests in North America, from disappearing
The statement comes from new research from Michigan State University and the National Audubon Society.
But the team’s report also reveals new opportunities to enhance the outlook for these birds by strategically expanding conservation and land management practices. Furthermore, the team’s approach can help inform conservation practices for other species.
Currently, black tern conservation efforts are focused on maintaining and restoring the bird’s breeding habitat to ensure there’s a place for the next generation to take flight.
It’s a sensible approach, but it also relies on adults surviving their migratory and overwintering periods.
As the team showed, that survival can’t be taken for granted.
Kayla Davis, first author of the new report and a doctoral student in the College of Natural Science at MSU, said: “What’s going on outside the breeding season and away from the breeding grounds is really important for this bird and, likely, other migratory species.
“There are things we can do to protect stopover and overwintering areas to increase adult survival.”
Co-author Sarah Saunders, senior manager of quantitative science at the National Audubon Society, added: “Fortunately, Audubon’s network of members and centres allows us to have an expansive conservation reach.
“Thanks to this work, now we know where to target efforts to help recover this species more effectively.”
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Black tern population
Prior to this collaboration between MSU and Audubon, it’s been challenging for researchers to develop reliable projections for how the black tern population would respond to different conservation strategies.
Those challenges were largely rooted in how hard it is to observe the birds, Davis said. As a result, data on black terns are sparse, limiting the precision of computational models used to inform conservation practices.
But Davis works in the lab of Elise Zipkin, an associate professor of integrative biology and the director of the Ecology, Evolution and Behavior program, or EEB, at MSU. One of the Zipkin lab’s specialties is developing and implementing models for species lacking data.
Zipkin said: “Because of data limitations, assessing wildlife trends is often only possible for common or easily identifiable species.
“But our lab is interested in developing approaches that make use of every piece of available information so that we can tackle those tough questions on rare and elusive species.”
Still, the black tern was an extreme case. Thankfully, the MSU researchers had partnered with one of the world’s foremost conservation societies.
Staff and volunteers with Detroit Audubon and Audubon Great Lakes – regional offices of the National Audubon Society – were able to gather valuable data about black terns through a variety of methods.
Saunders said: “One of the newest methods for tracking birds is the use of nanotags as part of the Motus Wildlife Tracking System.
“We were able to deploy tags on pre-fledged black tern chicks, which allowed us to understand how many birds were fledging each year and where they travelled during migration.
“This gave us new insights we wouldn’t have known otherwise, such as their use of national wildlife refuges along the Atlantic coast for refuelling during fall migration.”
Michigan black terns
Usually, each different data set that the team collected would be analysed with its own separate model.
For this project, using what’s known as an integrated population model, the team was able to bring typically disparate data together under a single analytical framework.
Though the data were still scant, the researchers were able to examine the information in a more cohesive way, revealing more about the population dynamics of Michigan black terns.
Davis said: “This way, we can make our estimates more accurate and precise than we could with any other model individually.”
For this project, the researchers worked at a black tern breeding colony at the St Clair Flats State Wildlife Area, near where the base of Michigan’s thumb region connects to Canada.
This site is actively managed by the Michigan Department of Natural Resources, another key partner in this project.
Based on its analysis, the team estimated that the average number of adult tern breeding pairs at St Clair Flats dropped from more than 300 in 2013 to roughly 50 in 2022.
The results show that promoting adult survival at other important areas along their migration – such as where birds rest and spend their winters – may be necessary in addition to current efforts that protect breeding sites.
Stephanie Beilke, Audubon Great Lakes senior manager of conservation science and a co-author of the report, said: “Of course, continuing to manage black tern breeding sites is important, too. We need a collaborative approach to saving this species and that means connecting with partners abroad and at home.”
Another key takeaway from this project is simply that the team’s approach worked. That’s good news for species beyond the black tern.
Davis said: “To be able to say something about conservation and land management implications with so little data is really encouraging because there are so many species out there that are data deficient. This modelling framework is really powerful.”
The study is published in Biological Conservation.
Image: Credit: Caleb Putnam, CC BY 2.0 <https://creativecommons.org/licenses/by/2.0>, via Wikimedia Commons.
